2019-06-04 11:11:33 +03:00
// SPDX-License-Identifier: GPL-2.0-only
2007-07-09 20:52:00 +04:00
/*
2011-11-15 20:14:39 +04:00
* kernel / sched / debug . c
2007-07-09 20:52:00 +04:00
*
2018-03-03 14:20:47 +03:00
* Print the CFS rbtree and other debugging details
2007-07-09 20:52:00 +04:00
*
* Copyright ( C ) 2007 , Red Hat , Inc . , Ingo Molnar
*/
2011-10-25 12:00:11 +04:00
2007-07-09 20:52:00 +04:00
/*
2023-09-20 16:00:25 +03:00
* This allows printing both to / sys / kernel / debug / sched / debug and
2007-07-09 20:52:00 +04:00
* to the console
*/
# define SEQ_printf(m, x...) \
do { \
if ( m ) \
seq_printf ( m , x ) ; \
else \
2018-03-19 21:35:54 +03:00
pr_cont ( x ) ; \
2007-07-09 20:52:00 +04:00
} while ( 0 )
2007-10-15 19:00:08 +04:00
/*
* Ease the printing of nsec fields :
*/
2007-12-30 19:24:35 +03:00
static long long nsec_high ( unsigned long long nsec )
2007-10-15 19:00:08 +04:00
{
2007-12-30 19:24:35 +03:00
if ( ( long long ) nsec < 0 ) {
2007-10-15 19:00:08 +04:00
nsec = - nsec ;
do_div ( nsec , 1000000 ) ;
return - nsec ;
}
do_div ( nsec , 1000000 ) ;
return nsec ;
}
2007-12-30 19:24:35 +03:00
static unsigned long nsec_low ( unsigned long long nsec )
2007-10-15 19:00:08 +04:00
{
2007-12-30 19:24:35 +03:00
if ( ( long long ) nsec < 0 )
2007-10-15 19:00:08 +04:00
nsec = - nsec ;
return do_div ( nsec , 1000000 ) ;
}
# define SPLIT_NS(x) nsec_high(x), nsec_low(x)
2016-02-23 00:26:50 +03:00
# define SCHED_FEAT(name, enabled) \
# name ,
static const char * const sched_feat_names [ ] = {
# include "features.h"
} ;
# undef SCHED_FEAT
static int sched_feat_show ( struct seq_file * m , void * v )
{
int i ;
for ( i = 0 ; i < __SCHED_FEAT_NR ; i + + ) {
if ( ! ( sysctl_sched_features & ( 1UL < < i ) ) )
seq_puts ( m , " NO_ " ) ;
seq_printf ( m , " %s " , sched_feat_names [ i ] ) ;
}
seq_puts ( m , " \n " ) ;
return 0 ;
}
2018-12-30 18:14:15 +03:00
# ifdef CONFIG_JUMP_LABEL
2016-02-23 00:26:50 +03:00
# define jump_label_key__true STATIC_KEY_INIT_TRUE
# define jump_label_key__false STATIC_KEY_INIT_FALSE
# define SCHED_FEAT(name, enabled) \
jump_label_key__ # # enabled ,
struct static_key sched_feat_keys [ __SCHED_FEAT_NR ] = {
# include "features.h"
} ;
# undef SCHED_FEAT
static void sched_feat_disable ( int i )
{
2018-07-31 15:12:22 +03:00
static_key_disable_cpuslocked ( & sched_feat_keys [ i ] ) ;
2016-02-23 00:26:50 +03:00
}
static void sched_feat_enable ( int i )
{
2018-07-31 15:12:22 +03:00
static_key_enable_cpuslocked ( & sched_feat_keys [ i ] ) ;
2016-02-23 00:26:50 +03:00
}
# else
static void sched_feat_disable ( int i ) { } ;
static void sched_feat_enable ( int i ) { } ;
2018-12-30 18:14:15 +03:00
# endif /* CONFIG_JUMP_LABEL */
2016-02-23 00:26:50 +03:00
static int sched_feat_set ( char * cmp )
{
int i ;
int neg = 0 ;
if ( strncmp ( cmp , " NO_ " , 3 ) = = 0 ) {
neg = 1 ;
cmp + = 3 ;
}
2018-05-31 14:11:19 +03:00
i = match_string ( sched_feat_names , __SCHED_FEAT_NR , cmp ) ;
if ( i < 0 )
return i ;
if ( neg ) {
sysctl_sched_features & = ~ ( 1UL < < i ) ;
sched_feat_disable ( i ) ;
} else {
sysctl_sched_features | = ( 1UL < < i ) ;
sched_feat_enable ( i ) ;
2016-02-23 00:26:50 +03:00
}
2018-05-31 14:11:19 +03:00
return 0 ;
2016-02-23 00:26:50 +03:00
}
static ssize_t
sched_feat_write ( struct file * filp , const char __user * ubuf ,
size_t cnt , loff_t * ppos )
{
char buf [ 64 ] ;
char * cmp ;
2018-05-31 14:11:19 +03:00
int ret ;
2016-02-23 00:26:50 +03:00
struct inode * inode ;
if ( cnt > 63 )
cnt = 63 ;
if ( copy_from_user ( & buf , ubuf , cnt ) )
return - EFAULT ;
buf [ cnt ] = 0 ;
cmp = strstrip ( buf ) ;
/* Ensure the static_key remains in a consistent state */
inode = file_inode ( filp ) ;
2018-07-31 15:12:22 +03:00
cpus_read_lock ( ) ;
2016-02-23 00:26:50 +03:00
inode_lock ( inode ) ;
2018-05-31 14:11:19 +03:00
ret = sched_feat_set ( cmp ) ;
2016-02-23 00:26:50 +03:00
inode_unlock ( inode ) ;
2018-07-31 15:12:22 +03:00
cpus_read_unlock ( ) ;
2018-05-31 14:11:19 +03:00
if ( ret < 0 )
return ret ;
2016-02-23 00:26:50 +03:00
* ppos + = cnt ;
return cnt ;
}
static int sched_feat_open ( struct inode * inode , struct file * filp )
{
return single_open ( filp , sched_feat_show , NULL ) ;
}
static const struct file_operations sched_feat_fops = {
. open = sched_feat_open ,
. write = sched_feat_write ,
. read = seq_read ,
. llseek = seq_lseek ,
. release = single_release ,
} ;
2021-03-24 13:43:21 +03:00
# ifdef CONFIG_SMP
static ssize_t sched_scaling_write ( struct file * filp , const char __user * ubuf ,
size_t cnt , loff_t * ppos )
{
char buf [ 16 ] ;
2021-09-27 14:46:35 +03:00
unsigned int scaling ;
2021-03-24 13:43:21 +03:00
if ( cnt > 15 )
cnt = 15 ;
if ( copy_from_user ( & buf , ubuf , cnt ) )
return - EFAULT ;
2021-09-27 14:46:35 +03:00
buf [ cnt ] = ' \0 ' ;
2021-03-24 13:43:21 +03:00
2021-09-27 14:46:35 +03:00
if ( kstrtouint ( buf , 10 , & scaling ) )
2021-03-24 13:43:21 +03:00
return - EINVAL ;
2021-09-27 14:46:35 +03:00
if ( scaling > = SCHED_TUNABLESCALING_END )
return - EINVAL ;
sysctl_sched_tunable_scaling = scaling ;
2021-03-24 13:43:21 +03:00
if ( sched_update_scaling ( ) )
return - EINVAL ;
* ppos + = cnt ;
return cnt ;
}
static int sched_scaling_show ( struct seq_file * m , void * v )
{
seq_printf ( m , " %d \n " , sysctl_sched_tunable_scaling ) ;
return 0 ;
}
static int sched_scaling_open ( struct inode * inode , struct file * filp )
{
return single_open ( filp , sched_scaling_show , NULL ) ;
}
static const struct file_operations sched_scaling_fops = {
. open = sched_scaling_open ,
. write = sched_scaling_write ,
. read = seq_read ,
. llseek = seq_lseek ,
. release = single_release ,
} ;
# endif /* SMP */
2021-03-25 14:21:38 +03:00
# ifdef CONFIG_PREEMPT_DYNAMIC
static ssize_t sched_dynamic_write ( struct file * filp , const char __user * ubuf ,
size_t cnt , loff_t * ppos )
{
char buf [ 16 ] ;
int mode ;
if ( cnt > 15 )
cnt = 15 ;
if ( copy_from_user ( & buf , ubuf , cnt ) )
return - EFAULT ;
buf [ cnt ] = 0 ;
mode = sched_dynamic_mode ( strstrip ( buf ) ) ;
if ( mode < 0 )
return mode ;
sched_dynamic_update ( mode ) ;
* ppos + = cnt ;
return cnt ;
}
static int sched_dynamic_show ( struct seq_file * m , void * v )
{
static const char * preempt_modes [ ] = {
" none " , " voluntary " , " full "
} ;
int i ;
for ( i = 0 ; i < ARRAY_SIZE ( preempt_modes ) ; i + + ) {
if ( preempt_dynamic_mode = = i )
seq_puts ( m , " ( " ) ;
seq_puts ( m , preempt_modes [ i ] ) ;
if ( preempt_dynamic_mode = = i )
seq_puts ( m , " ) " ) ;
seq_puts ( m , " " ) ;
}
seq_puts ( m , " \n " ) ;
return 0 ;
}
static int sched_dynamic_open ( struct inode * inode , struct file * filp )
{
return single_open ( filp , sched_dynamic_show , NULL ) ;
}
static const struct file_operations sched_dynamic_fops = {
. open = sched_dynamic_open ,
. write = sched_dynamic_write ,
. read = seq_read ,
. llseek = seq_lseek ,
. release = single_release ,
} ;
# endif /* CONFIG_PREEMPT_DYNAMIC */
2021-04-15 19:23:17 +03:00
__read_mostly bool sched_debug_verbose ;
2017-09-07 18:03:53 +03:00
2023-03-03 21:37:54 +03:00
# ifdef CONFIG_SMP
static struct dentry * sd_dentry ;
static ssize_t sched_verbose_write ( struct file * filp , const char __user * ubuf ,
size_t cnt , loff_t * ppos )
{
ssize_t result ;
bool orig ;
cpus_read_lock ( ) ;
mutex_lock ( & sched_domains_mutex ) ;
orig = sched_debug_verbose ;
result = debugfs_write_file_bool ( filp , ubuf , cnt , ppos ) ;
if ( sched_debug_verbose & & ! orig )
update_sched_domain_debugfs ( ) ;
else if ( ! sched_debug_verbose & & orig ) {
debugfs_remove ( sd_dentry ) ;
sd_dentry = NULL ;
}
mutex_unlock ( & sched_domains_mutex ) ;
cpus_read_unlock ( ) ;
return result ;
}
# else
# define sched_verbose_write debugfs_write_file_bool
# endif
static const struct file_operations sched_verbose_fops = {
. read = debugfs_read_file_bool ,
. write = sched_verbose_write ,
. open = simple_open ,
. llseek = default_llseek ,
} ;
2021-03-25 17:18:19 +03:00
static const struct seq_operations sched_debug_sops ;
static int sched_debug_open ( struct inode * inode , struct file * filp )
{
return seq_open ( filp , & sched_debug_sops ) ;
}
static const struct file_operations sched_debug_fops = {
. open = sched_debug_open ,
. read = seq_read ,
. llseek = seq_lseek ,
. release = seq_release ,
} ;
2021-03-25 14:21:38 +03:00
static struct dentry * debugfs_sched ;
2021-03-24 13:43:21 +03:00
2016-02-23 00:26:50 +03:00
static __init int sched_init_debug ( void )
{
2021-03-24 13:43:21 +03:00
struct dentry __maybe_unused * numa ;
2016-02-23 00:26:50 +03:00
2021-03-24 13:43:21 +03:00
debugfs_sched = debugfs_create_dir ( " sched " , NULL ) ;
debugfs_create_file ( " features " , 0644 , debugfs_sched , NULL , & sched_feat_fops ) ;
2023-03-03 21:37:54 +03:00
debugfs_create_file_unsafe ( " verbose " , 0644 , debugfs_sched , & sched_debug_verbose , & sched_verbose_fops ) ;
2021-03-25 14:21:38 +03:00
# ifdef CONFIG_PREEMPT_DYNAMIC
debugfs_create_file ( " preempt " , 0644 , debugfs_sched , NULL , & sched_dynamic_fops ) ;
# endif
2021-03-24 13:43:21 +03:00
2023-05-31 14:58:48 +03:00
debugfs_create_u32 ( " base_slice_ns " , 0644 , debugfs_sched , & sysctl_sched_base_slice ) ;
2021-03-24 13:43:21 +03:00
2021-04-17 00:29:36 +03:00
debugfs_create_u32 ( " latency_warn_ms " , 0644 , debugfs_sched , & sysctl_resched_latency_warn_ms ) ;
debugfs_create_u32 ( " latency_warn_once " , 0644 , debugfs_sched , & sysctl_resched_latency_warn_once ) ;
2021-03-24 13:43:21 +03:00
# ifdef CONFIG_SMP
debugfs_create_file ( " tunable_scaling " , 0644 , debugfs_sched , NULL , & sched_scaling_fops ) ;
debugfs_create_u32 ( " migration_cost_ns " , 0644 , debugfs_sched , & sysctl_sched_migration_cost ) ;
debugfs_create_u32 ( " nr_migrate " , 0644 , debugfs_sched , & sysctl_sched_nr_migrate ) ;
2021-03-25 13:31:20 +03:00
mutex_lock ( & sched_domains_mutex ) ;
update_sched_domain_debugfs ( ) ;
mutex_unlock ( & sched_domains_mutex ) ;
2021-03-24 13:43:21 +03:00
# endif
# ifdef CONFIG_NUMA_BALANCING
numa = debugfs_create_dir ( " numa_balancing " , debugfs_sched ) ;
debugfs_create_u32 ( " scan_delay_ms " , 0644 , numa , & sysctl_numa_balancing_scan_delay ) ;
debugfs_create_u32 ( " scan_period_min_ms " , 0644 , numa , & sysctl_numa_balancing_scan_period_min ) ;
debugfs_create_u32 ( " scan_period_max_ms " , 0644 , numa , & sysctl_numa_balancing_scan_period_max ) ;
debugfs_create_u32 ( " scan_size_mb " , 0644 , numa , & sysctl_numa_balancing_scan_size ) ;
memory tiering: hot page selection with hint page fault latency
Patch series "memory tiering: hot page selection", v4.
To optimize page placement in a memory tiering system with NUMA balancing,
the hot pages in the slow memory nodes need to be identified.
Essentially, the original NUMA balancing implementation selects the mostly
recently accessed (MRU) pages to promote. But this isn't a perfect
algorithm to identify the hot pages. Because the pages with quite low
access frequency may be accessed eventually given the NUMA balancing page
table scanning period could be quite long (e.g. 60 seconds). So in this
patchset, we implement a new hot page identification algorithm based on
the latency between NUMA balancing page table scanning and hint page
fault. Which is a kind of mostly frequently accessed (MFU) algorithm.
In NUMA balancing memory tiering mode, if there are hot pages in slow
memory node and cold pages in fast memory node, we need to promote/demote
hot/cold pages between the fast and cold memory nodes.
A choice is to promote/demote as fast as possible. But the CPU cycles and
memory bandwidth consumed by the high promoting/demoting throughput will
hurt the latency of some workload because of accessing inflating and slow
memory bandwidth contention.
A way to resolve this issue is to restrict the max promoting/demoting
throughput. It will take longer to finish the promoting/demoting. But
the workload latency will be better. This is implemented in this patchset
as the page promotion rate limit mechanism.
The promotion hot threshold is workload and system configuration
dependent. So in this patchset, a method to adjust the hot threshold
automatically is implemented. The basic idea is to control the number of
the candidate promotion pages to match the promotion rate limit.
We used the pmbench memory accessing benchmark tested the patchset on a
2-socket server system with DRAM and PMEM installed. The test results are
as follows,
pmbench score promote rate
(accesses/s) MB/s
------------- ------------
base 146887704.1 725.6
hot selection 165695601.2 544.0
rate limit 162814569.8 165.2
auto adjustment 170495294.0 136.9
From the results above,
With hot page selection patch [1/3], the pmbench score increases about
12.8%, and promote rate (overhead) decreases about 25.0%, compared with
base kernel.
With rate limit patch [2/3], pmbench score decreases about 1.7%, and
promote rate decreases about 69.6%, compared with hot page selection
patch.
With threshold auto adjustment patch [3/3], pmbench score increases about
4.7%, and promote rate decrease about 17.1%, compared with rate limit
patch.
Baolin helped to test the patchset with MySQL on a machine which contains
1 DRAM node (30G) and 1 PMEM node (126G).
sysbench /usr/share/sysbench/oltp_read_write.lua \
......
--tables=200 \
--table-size=1000000 \
--report-interval=10 \
--threads=16 \
--time=120
The tps can be improved about 5%.
This patch (of 3):
To optimize page placement in a memory tiering system with NUMA balancing,
the hot pages in the slow memory node need to be identified. Essentially,
the original NUMA balancing implementation selects the mostly recently
accessed (MRU) pages to promote. But this isn't a perfect algorithm to
identify the hot pages. Because the pages with quite low access frequency
may be accessed eventually given the NUMA balancing page table scanning
period could be quite long (e.g. 60 seconds). The most frequently
accessed (MFU) algorithm is better.
So, in this patch we implemented a better hot page selection algorithm.
Which is based on NUMA balancing page table scanning and hint page fault
as follows,
- When the page tables of the processes are scanned to change PTE/PMD
to be PROT_NONE, the current time is recorded in struct page as scan
time.
- When the page is accessed, hint page fault will occur. The scan
time is gotten from the struct page. And The hint page fault
latency is defined as
hint page fault time - scan time
The shorter the hint page fault latency of a page is, the higher the
probability of their access frequency to be higher. So the hint page
fault latency is a better estimation of the page hot/cold.
It's hard to find some extra space in struct page to hold the scan time.
Fortunately, we can reuse some bits used by the original NUMA balancing.
NUMA balancing uses some bits in struct page to store the page accessing
CPU and PID (referring to page_cpupid_xchg_last()). Which is used by the
multi-stage node selection algorithm to avoid to migrate pages shared
accessed by the NUMA nodes back and forth. But for pages in the slow
memory node, even if they are shared accessed by multiple NUMA nodes, as
long as the pages are hot, they need to be promoted to the fast memory
node. So the accessing CPU and PID information are unnecessary for the
slow memory pages. We can reuse these bits in struct page to record the
scan time. For the fast memory pages, these bits are used as before.
For the hot threshold, the default value is 1 second, which works well in
our performance test. All pages with hint page fault latency < hot
threshold will be considered hot.
It's hard for users to determine the hot threshold. So we don't provide a
kernel ABI to set it, just provide a debugfs interface for advanced users
to experiment. We will continue to work on a hot threshold automatic
adjustment mechanism.
The downside of the above method is that the response time to the workload
hot spot changing may be much longer. For example,
- A previous cold memory area becomes hot
- The hint page fault will be triggered. But the hint page fault
latency isn't shorter than the hot threshold. So the pages will
not be promoted.
- When the memory area is scanned again, maybe after a scan period,
the hint page fault latency measured will be shorter than the hot
threshold and the pages will be promoted.
To mitigate this, if there are enough free space in the fast memory node,
the hot threshold will not be used, all pages will be promoted upon the
hint page fault for fast response.
Thanks Zhong Jiang reported and tested the fix for a bug when disabling
memory tiering mode dynamically.
Link: https://lkml.kernel.org/r/20220713083954.34196-1-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20220713083954.34196-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Wei Xu <weixugc@google.com>
Cc: osalvador <osalvador@suse.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Zhong Jiang <zhongjiang-ali@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-07-13 11:39:51 +03:00
debugfs_create_u32 ( " hot_threshold_ms " , 0644 , numa , & sysctl_numa_balancing_hot_threshold ) ;
2021-03-24 13:43:21 +03:00
# endif
2017-09-07 18:03:53 +03:00
2021-03-25 17:18:19 +03:00
debugfs_create_file ( " debug " , 0444 , debugfs_sched , NULL , & sched_debug_fops ) ;
2016-02-23 00:26:50 +03:00
return 0 ;
}
late_initcall ( sched_init_debug ) ;
2016-02-23 00:26:51 +03:00
# ifdef CONFIG_SMP
2021-03-25 13:31:20 +03:00
static cpumask_var_t sd_sysctl_cpus ;
2016-02-23 00:26:51 +03:00
2021-03-25 13:31:20 +03:00
static int sd_flags_show ( struct seq_file * m , void * v )
2020-08-17 14:29:52 +03:00
{
2021-03-25 13:31:20 +03:00
unsigned long flags = * ( unsigned int * ) m - > private ;
2020-08-17 14:29:52 +03:00
int idx ;
for_each_set_bit ( idx , & flags , __SD_FLAG_CNT ) {
2021-03-25 13:31:20 +03:00
seq_puts ( m , sd_flag_debug [ idx ] . name ) ;
seq_puts ( m , " " ) ;
2020-08-17 14:29:52 +03:00
}
2021-03-25 13:31:20 +03:00
seq_puts ( m , " \n " ) ;
2020-08-17 14:29:52 +03:00
return 0 ;
}
2021-03-25 13:31:20 +03:00
static int sd_flags_open ( struct inode * inode , struct file * file )
2016-02-23 00:26:51 +03:00
{
2021-03-25 13:31:20 +03:00
return single_open ( file , sd_flags_show , inode - > i_private ) ;
2016-02-23 00:26:51 +03:00
}
2021-03-25 13:31:20 +03:00
static const struct file_operations sd_flags_fops = {
. open = sd_flags_open ,
. read = seq_read ,
. llseek = seq_lseek ,
. release = single_release ,
} ;
2017-08-10 18:10:26 +03:00
2021-03-25 13:31:20 +03:00
static void register_sd ( struct sched_domain * sd , struct dentry * parent )
2016-02-23 00:26:51 +03:00
{
2021-03-25 13:31:20 +03:00
# define SDM(type, mode, member) \
debugfs_create_ # # type ( # member , mode , parent , & sd - > member )
2016-02-23 00:26:51 +03:00
2021-03-25 13:31:20 +03:00
SDM ( ulong , 0644 , min_interval ) ;
SDM ( ulong , 0644 , max_interval ) ;
SDM ( u64 , 0644 , max_newidle_lb_cost ) ;
SDM ( u32 , 0644 , busy_factor ) ;
SDM ( u32 , 0644 , imbalance_pct ) ;
SDM ( u32 , 0644 , cache_nice_tries ) ;
SDM ( str , 0444 , name ) ;
2016-02-23 00:26:51 +03:00
2021-03-25 13:31:20 +03:00
# undef SDM
2017-08-10 18:10:26 +03:00
2021-03-25 13:31:20 +03:00
debugfs_create_file ( " flags " , 0444 , parent , & sd - > flags , & sd_flags_fops ) ;
2023-07-08 01:57:05 +03:00
debugfs_create_file ( " groups_flags " , 0444 , parent , & sd - > groups - > flags , & sd_flags_fops ) ;
2021-03-25 13:31:20 +03:00
}
2017-08-10 18:10:26 +03:00
2021-03-25 13:31:20 +03:00
void update_sched_domain_debugfs ( void )
{
int cpu , i ;
2017-08-10 18:10:26 +03:00
sched/debug: Don't update sched_domain debug directories before sched_debug_init()
Since CPU capacity asymmetry can stem purely from maximum frequency
differences (e.g. Pixel 1), a rebuild of the scheduler topology can be
issued upon loading cpufreq, see:
arch_topology.c::init_cpu_capacity_callback()
Turns out that if this rebuild happens *before* sched_debug_init() is
run (which is a late initcall), we end up messing up the sched_domain debug
directory: passing a NULL parent to debugfs_create_dir() ends up creating
the directory at the debugfs root, which in this case creates
/sys/kernel/debug/domains (instead of /sys/kernel/debug/sched/domains).
This currently doesn't happen on asymmetric systems which use cpufreq-scpi
or cpufreq-dt drivers, as those are loaded via
deferred_probe_initcall() (it is also a late initcall, but appears to be
ordered *after* sched_debug_init()).
Ionela has been working on detecting maximum frequency asymmetry via ACPI,
and that actually happens via a *device* initcall, thus before
sched_debug_init(), and causes the aforementionned debugfs mayhem.
One option would be to punt sched_debug_init() down to
fs_initcall_sync(). Preventing update_sched_domain_debugfs() from running
before sched_debug_init() appears to be the safer option.
Fixes: 3b87f136f8fc ("sched,debug: Convert sysctl sched_domains to debugfs")
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lore.kernel.org/r/20210514095339.12979-1-ionela.voinescu@arm.com
2021-05-18 16:07:25 +03:00
/*
* This can unfortunately be invoked before sched_debug_init ( ) creates
* the debug directory . Don ' t touch sd_sysctl_cpus until then .
*/
if ( ! debugfs_sched )
return ;
2023-03-03 21:37:54 +03:00
if ( ! sched_debug_verbose )
return ;
2017-08-10 18:10:26 +03:00
if ( ! cpumask_available ( sd_sysctl_cpus ) ) {
if ( ! alloc_cpumask_var ( & sd_sysctl_cpus , GFP_KERNEL ) )
return ;
cpumask_copy ( sd_sysctl_cpus , cpu_possible_mask ) ;
}
2023-03-03 21:37:54 +03:00
if ( ! sd_dentry ) {
2021-03-25 13:31:20 +03:00
sd_dentry = debugfs_create_dir ( " domains " , debugfs_sched ) ;
2023-03-03 21:37:54 +03:00
/* rebuild sd_sysctl_cpus if empty since it gets cleared below */
if ( cpumask_empty ( sd_sysctl_cpus ) )
cpumask_copy ( sd_sysctl_cpus , cpu_online_mask ) ;
}
2021-03-25 13:31:20 +03:00
for_each_cpu ( cpu , sd_sysctl_cpus ) {
struct sched_domain * sd ;
struct dentry * d_cpu ;
char buf [ 32 ] ;
snprintf ( buf , sizeof ( buf ) , " cpu%d " , cpu ) ;
2022-09-02 15:31:07 +03:00
debugfs_lookup_and_remove ( buf , sd_dentry ) ;
2021-03-25 13:31:20 +03:00
d_cpu = debugfs_create_dir ( buf , sd_dentry ) ;
i = 0 ;
for_each_domain ( cpu , sd ) {
struct dentry * d_sd ;
2017-08-10 18:10:26 +03:00
2021-03-25 13:31:20 +03:00
snprintf ( buf , sizeof ( buf ) , " domain%d " , i ) ;
d_sd = debugfs_create_dir ( buf , d_cpu ) ;
2017-08-10 18:10:26 +03:00
2021-03-25 13:31:20 +03:00
register_sd ( sd , d_sd ) ;
i + + ;
2017-08-10 18:10:26 +03:00
}
2021-03-25 13:31:20 +03:00
__cpumask_clear_cpu ( cpu , sd_sysctl_cpus ) ;
2016-02-23 00:26:51 +03:00
}
}
2017-08-10 18:10:26 +03:00
void dirty_sched_domain_sysctl ( int cpu )
{
if ( cpumask_available ( sd_sysctl_cpus ) )
__cpumask_set_cpu ( cpu , sd_sysctl_cpus ) ;
}
2016-02-23 00:26:51 +03:00
# endif /* CONFIG_SMP */
2008-11-10 19:04:09 +03:00
# ifdef CONFIG_FAIR_GROUP_SCHED
sched: Add 'autogroup' scheduling feature: automated per session task groups
A recurring complaint from CFS users is that parallel kbuild has
a negative impact on desktop interactivity. This patch
implements an idea from Linus, to automatically create task
groups. Currently, only per session autogroups are implemented,
but the patch leaves the way open for enhancement.
Implementation: each task's signal struct contains an inherited
pointer to a refcounted autogroup struct containing a task group
pointer, the default for all tasks pointing to the
init_task_group. When a task calls setsid(), a new task group
is created, the process is moved into the new task group, and a
reference to the preveious task group is dropped. Child
processes inherit this task group thereafter, and increase it's
refcount. When the last thread of a process exits, the
process's reference is dropped, such that when the last process
referencing an autogroup exits, the autogroup is destroyed.
At runqueue selection time, IFF a task has no cgroup assignment,
its current autogroup is used.
Autogroup bandwidth is controllable via setting it's nice level
through the proc filesystem:
cat /proc/<pid>/autogroup
Displays the task's group and the group's nice level.
echo <nice level> > /proc/<pid>/autogroup
Sets the task group's shares to the weight of nice <level> task.
Setting nice level is rate limited for !admin users due to the
abuse risk of task group locking.
The feature is enabled from boot by default if
CONFIG_SCHED_AUTOGROUP=y is selected, but can be disabled via
the boot option noautogroup, and can also be turned on/off on
the fly via:
echo [01] > /proc/sys/kernel/sched_autogroup_enabled
... which will automatically move tasks to/from the root task group.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Paul Turner <pjt@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
[ Removed the task_group_path() debug code, and fixed !EVENTFD build failure. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1290281700.28711.9.camel@maggy.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-11-30 16:18:03 +03:00
static void print_cfs_group_stats ( struct seq_file * m , int cpu , struct task_group * tg )
2008-11-10 19:04:09 +03:00
{
struct sched_entity * se = tg - > se [ cpu ] ;
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
# define P(F) SEQ_printf(m, " .%-30s: %lld\n", #F, (long long)F)
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
# define P_SCHEDSTAT(F) SEQ_printf(m, " .%-30s: %lld\n", \
# F, (long long)schedstat_val(stats->F))
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
# define PN(F) SEQ_printf(m, " .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
# define PN_SCHEDSTAT(F) SEQ_printf(m, " .%-30s: %lld.%06ld\n", \
# F, SPLIT_NS((long long)schedstat_val(stats->F)))
2008-11-10 19:04:09 +03:00
2015-07-15 03:04:36 +03:00
if ( ! se )
2012-10-04 14:51:20 +04:00
return ;
2008-11-10 19:04:09 +03:00
PN ( se - > exec_start ) ;
PN ( se - > vruntime ) ;
PN ( se - > sum_exec_runtime ) ;
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
2016-02-05 12:08:36 +03:00
if ( schedstat_enabled ( ) ) {
2021-10-06 11:12:05 +03:00
struct sched_statistics * stats ;
stats = __schedstats_from_se ( se ) ;
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
PN_SCHEDSTAT ( wait_start ) ;
PN_SCHEDSTAT ( sleep_start ) ;
PN_SCHEDSTAT ( block_start ) ;
PN_SCHEDSTAT ( sleep_max ) ;
PN_SCHEDSTAT ( block_max ) ;
PN_SCHEDSTAT ( exec_max ) ;
PN_SCHEDSTAT ( slice_max ) ;
PN_SCHEDSTAT ( wait_max ) ;
PN_SCHEDSTAT ( wait_sum ) ;
P_SCHEDSTAT ( wait_count ) ;
2016-02-05 12:08:36 +03:00
}
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
2008-11-10 19:04:09 +03:00
P ( se - > load . weight ) ;
2012-10-04 15:18:29 +04:00
# ifdef CONFIG_SMP
sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-15 03:04:37 +03:00
P ( se - > avg . load_avg ) ;
P ( se - > avg . util_avg ) ;
2020-02-24 12:52:18 +03:00
P ( se - > avg . runnable_avg ) ;
2012-10-04 15:18:29 +04:00
# endif
2016-06-17 20:43:26 +03:00
# undef PN_SCHEDSTAT
2008-11-10 19:04:09 +03:00
# undef PN
2016-06-17 20:43:26 +03:00
# undef P_SCHEDSTAT
2008-11-10 19:04:09 +03:00
# undef P
}
# endif
2011-01-11 13:11:54 +03:00
# ifdef CONFIG_CGROUP_SCHED
2021-04-15 22:54:26 +03:00
static DEFINE_SPINLOCK ( sched_debug_lock ) ;
2011-01-11 13:11:54 +03:00
static char group_path [ PATH_MAX ] ;
2021-04-15 22:54:26 +03:00
static void task_group_path ( struct task_group * tg , char * path , int plen )
2011-01-11 13:11:54 +03:00
{
2021-04-15 22:54:26 +03:00
if ( autogroup_path ( tg , path , plen ) )
return ;
2011-01-11 13:12:57 +03:00
2021-04-15 22:54:26 +03:00
cgroup_path ( tg - > css . cgroup , path , plen ) ;
}
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
2021-04-15 22:54:26 +03:00
/*
* Only 1 SEQ_printf_task_group_path ( ) caller can use the full length
* group_path [ ] for cgroup path . Other simultaneous callers will have
* to use a shorter stack buffer . A " ... " suffix is appended at the end
* of the stack buffer so that it will show up in case the output length
* matches the given buffer size to indicate possible path name truncation .
*/
# define SEQ_printf_task_group_path(m, tg, fmt...) \
{ \
if ( spin_trylock ( & sched_debug_lock ) ) { \
task_group_path ( tg , group_path , sizeof ( group_path ) ) ; \
SEQ_printf ( m , fmt , group_path ) ; \
spin_unlock ( & sched_debug_lock ) ; \
} else { \
char buf [ 128 ] ; \
char * bufend = buf + sizeof ( buf ) - 3 ; \
task_group_path ( tg , buf , bufend - buf ) ; \
strcpy ( bufend - 1 , " ... " ) ; \
SEQ_printf ( m , fmt , buf ) ; \
} \
2011-01-11 13:11:54 +03:00
}
# endif
2007-07-09 20:52:00 +04:00
static void
2007-08-09 13:16:51 +04:00
print_task ( struct seq_file * m , struct rq * rq , struct task_struct * p )
2007-07-09 20:52:00 +04:00
{
2020-10-30 20:32:23 +03:00
if ( task_current ( rq , p ) )
2017-08-07 11:44:22 +03:00
SEQ_printf ( m , " >R " ) ;
2017-08-07 11:44:23 +03:00
else
SEQ_printf ( m , " %c " , task_state_to_char ( p ) ) ;
2007-07-09 20:52:00 +04:00
sched/fair: Implement an EEVDF-like scheduling policy
Where CFS is currently a WFQ based scheduler with only a single knob,
the weight. The addition of a second, latency oriented parameter,
makes something like WF2Q or EEVDF based a much better fit.
Specifically, EEVDF does EDF like scheduling in the left half of the
tree -- those entities that are owed service. Except because this is a
virtual time scheduler, the deadlines are in virtual time as well,
which is what allows over-subscription.
EEVDF has two parameters:
- weight, or time-slope: which is mapped to nice just as before
- request size, or slice length: which is used to compute
the virtual deadline as: vd_i = ve_i + r_i/w_i
Basically, by setting a smaller slice, the deadline will be earlier
and the task will be more eligible and ran earlier.
Tick driven preemption is driven by request/slice completion; while
wakeup preemption is driven by the deadline.
Because the tree is now effectively an interval tree, and the
selection is no longer 'leftmost', over-scheduling is less of a
problem.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.931005524@infradead.org
2023-05-31 14:58:44 +03:00
SEQ_printf ( m , " %15s %5d %9Ld.%06ld %c %9Ld.%06ld %9Ld.%06ld %9Ld.%06ld %9Ld %5d " ,
2013-09-09 15:01:41 +04:00
p - > comm , task_pid_nr ( p ) ,
2007-10-15 19:00:08 +04:00
SPLIT_NS ( p - > se . vruntime ) ,
sched/fair: Implement an EEVDF-like scheduling policy
Where CFS is currently a WFQ based scheduler with only a single knob,
the weight. The addition of a second, latency oriented parameter,
makes something like WF2Q or EEVDF based a much better fit.
Specifically, EEVDF does EDF like scheduling in the left half of the
tree -- those entities that are owed service. Except because this is a
virtual time scheduler, the deadlines are in virtual time as well,
which is what allows over-subscription.
EEVDF has two parameters:
- weight, or time-slope: which is mapped to nice just as before
- request size, or slice length: which is used to compute
the virtual deadline as: vd_i = ve_i + r_i/w_i
Basically, by setting a smaller slice, the deadline will be earlier
and the task will be more eligible and ran earlier.
Tick driven preemption is driven by request/slice completion; while
wakeup preemption is driven by the deadline.
Because the tree is now effectively an interval tree, and the
selection is no longer 'leftmost', over-scheduling is less of a
problem.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.931005524@infradead.org
2023-05-31 14:58:44 +03:00
entity_eligible ( cfs_rq_of ( & p - > se ) , & p - > se ) ? ' E ' : ' N ' ,
SPLIT_NS ( p - > se . deadline ) ,
SPLIT_NS ( p - > se . slice ) ,
SPLIT_NS ( p - > se . sum_exec_runtime ) ,
2007-07-09 20:52:00 +04:00
( long long ) ( p - > nvcsw + p - > nivcsw ) ,
2007-08-06 07:26:59 +04:00
p - > prio ) ;
2016-06-04 01:58:40 +03:00
2021-09-05 17:35:43 +03:00
SEQ_printf ( m , " %9lld.%06ld %9lld.%06ld %9lld.%06ld %9lld.%06ld " ,
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
SPLIT_NS ( schedstat_val_or_zero ( p - > stats . wait_sum ) ) ,
2015-06-08 11:10:39 +03:00
SPLIT_NS ( p - > se . sum_exec_runtime ) ,
2021-09-05 17:35:43 +03:00
SPLIT_NS ( schedstat_val_or_zero ( p - > stats . sum_sleep_runtime ) ) ,
SPLIT_NS ( schedstat_val_or_zero ( p - > stats . sum_block_runtime ) ) ) ;
2016-06-04 01:58:40 +03:00
2013-10-07 14:29:30 +04:00
# ifdef CONFIG_NUMA_BALANCING
2015-06-25 20:21:42 +03:00
SEQ_printf ( m , " %d %d " , task_node ( p ) , task_numa_group_id ( p ) ) ;
2013-10-07 14:29:30 +04:00
# endif
2011-01-11 13:11:54 +03:00
# ifdef CONFIG_CGROUP_SCHED
2021-04-15 22:54:26 +03:00
SEQ_printf_task_group_path ( m , task_group ( p ) , " %s " )
2011-01-11 13:11:54 +03:00
# endif
2008-04-19 21:45:00 +04:00
SEQ_printf ( m , " \n " ) ;
2007-07-09 20:52:00 +04:00
}
2007-08-09 13:16:51 +04:00
static void print_rq ( struct seq_file * m , struct rq * rq , int rq_cpu )
2007-07-09 20:52:00 +04:00
{
struct task_struct * g , * p ;
2018-03-19 21:35:55 +03:00
SEQ_printf ( m , " \n " ) ;
SEQ_printf ( m , " runnable tasks: \n " ) ;
2020-04-14 15:57:21 +03:00
SEQ_printf ( m , " S task PID tree-key switches prio "
2018-03-19 21:35:55 +03:00
" wait-time sum-exec sum-sleep \n " ) ;
SEQ_printf ( m , " ------------------------------------------------------- "
2020-04-14 15:57:21 +03:00
" ------------------------------------------------------ \n " ) ;
2007-07-09 20:52:00 +04:00
2014-09-21 23:33:41 +04:00
rcu_read_lock ( ) ;
2014-08-13 23:19:56 +04:00
for_each_process_thread ( g , p ) {
2013-10-07 14:29:30 +04:00
if ( task_cpu ( p ) ! = rq_cpu )
2007-07-09 20:52:00 +04:00
continue ;
2007-08-09 13:16:51 +04:00
print_task ( m , rq , p ) ;
2014-08-13 23:19:56 +04:00
}
2014-09-21 23:33:41 +04:00
rcu_read_unlock ( ) ;
2007-07-09 20:52:00 +04:00
}
2007-08-09 13:16:47 +04:00
void print_cfs_rq ( struct seq_file * m , int cpu , struct cfs_rq * cfs_rq )
2007-07-09 20:52:00 +04:00
{
2023-05-31 14:58:40 +03:00
s64 left_vruntime = - 1 , min_vruntime , right_vruntime = - 1 , spread ;
struct sched_entity * last , * first ;
2009-06-17 17:20:55 +04:00
struct rq * rq = cpu_rq ( cpu ) ;
2007-10-15 19:00:05 +04:00
unsigned long flags ;
2011-01-11 13:11:54 +03:00
# ifdef CONFIG_FAIR_GROUP_SCHED
2018-03-19 21:35:55 +03:00
SEQ_printf ( m , " \n " ) ;
2021-04-15 22:54:26 +03:00
SEQ_printf_task_group_path ( m , cfs_rq - > tg , " cfs_rq[%d]:%s \n " , cpu ) ;
2011-01-11 13:11:54 +03:00
# else
2018-03-19 21:35:55 +03:00
SEQ_printf ( m , " \n " ) ;
SEQ_printf ( m , " cfs_rq[%d]: \n " , cpu ) ;
2011-01-11 13:11:54 +03:00
# endif
2007-10-15 19:00:08 +04:00
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , " exec_clock " ,
SPLIT_NS ( cfs_rq - > exec_clock ) ) ;
2007-10-15 19:00:05 +04:00
2020-11-18 02:19:31 +03:00
raw_spin_rq_lock_irqsave ( rq , flags ) ;
2023-05-31 14:58:40 +03:00
first = __pick_first_entity ( cfs_rq ) ;
if ( first )
left_vruntime = first - > vruntime ;
2007-10-15 19:00:05 +04:00
last = __pick_last_entity ( cfs_rq ) ;
if ( last )
2023-05-31 14:58:40 +03:00
right_vruntime = last - > vruntime ;
2008-11-10 12:46:32 +03:00
min_vruntime = cfs_rq - > min_vruntime ;
2020-11-18 02:19:31 +03:00
raw_spin_rq_unlock_irqrestore ( rq , flags ) ;
2023-05-31 14:58:40 +03:00
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , " left_vruntime " ,
SPLIT_NS ( left_vruntime ) ) ;
2007-10-15 19:00:08 +04:00
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , " min_vruntime " ,
SPLIT_NS ( min_vruntime ) ) ;
2023-05-31 14:58:40 +03:00
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , " avg_vruntime " ,
SPLIT_NS ( avg_vruntime ( cfs_rq ) ) ) ;
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , " right_vruntime " ,
SPLIT_NS ( right_vruntime ) ) ;
spread = right_vruntime - left_vruntime ;
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , " spread " , SPLIT_NS ( spread ) ) ;
2008-11-10 12:46:32 +03:00
SEQ_printf ( m , " .%-30s: %d \n " , " nr_spread_over " ,
2007-10-15 19:00:10 +04:00
cfs_rq - > nr_spread_over ) ;
2012-04-26 15:12:27 +04:00
SEQ_printf ( m , " .%-30s: %d \n " , " nr_running " , cfs_rq - > nr_running ) ;
2021-07-30 05:00:18 +03:00
SEQ_printf ( m , " .%-30s: %d \n " , " h_nr_running " , cfs_rq - > h_nr_running ) ;
2021-08-20 04:04:01 +03:00
SEQ_printf ( m , " .%-30s: %d \n " , " idle_nr_running " ,
cfs_rq - > idle_nr_running ) ;
2021-07-30 05:00:18 +03:00
SEQ_printf ( m , " .%-30s: %d \n " , " idle_h_nr_running " ,
cfs_rq - > idle_h_nr_running ) ;
2010-11-16 02:47:00 +03:00
SEQ_printf ( m , " .%-30s: %ld \n " , " load " , cfs_rq - > load . weight ) ;
2008-06-27 15:41:14 +04:00
# ifdef CONFIG_SMP
sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-15 03:04:37 +03:00
SEQ_printf ( m , " .%-30s: %lu \n " , " load_avg " ,
cfs_rq - > avg . load_avg ) ;
2020-02-24 12:52:18 +03:00
SEQ_printf ( m , " .%-30s: %lu \n " , " runnable_avg " ,
cfs_rq - > avg . runnable_avg ) ;
sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-15 03:04:37 +03:00
SEQ_printf ( m , " .%-30s: %lu \n " , " util_avg " ,
cfs_rq - > avg . util_avg ) ;
sched/fair: Add util_est on top of PELT
The util_avg signal computed by PELT is too variable for some use-cases.
For example, a big task waking up after a long sleep period will have its
utilization almost completely decayed. This introduces some latency before
schedutil will be able to pick the best frequency to run a task.
The same issue can affect task placement. Indeed, since the task
utilization is already decayed at wakeup, when the task is enqueued in a
CPU, this can result in a CPU running a big task as being temporarily
represented as being almost empty. This leads to a race condition where
other tasks can be potentially allocated on a CPU which just started to run
a big task which slept for a relatively long period.
Moreover, the PELT utilization of a task can be updated every [ms], thus
making it a continuously changing value for certain longer running
tasks. This means that the instantaneous PELT utilization of a RUNNING
task is not really meaningful to properly support scheduler decisions.
For all these reasons, a more stable signal can do a better job of
representing the expected/estimated utilization of a task/cfs_rq.
Such a signal can be easily created on top of PELT by still using it as
an estimator which produces values to be aggregated on meaningful
events.
This patch adds a simple implementation of util_est, a new signal built on
top of PELT's util_avg where:
util_est(task) = max(task::util_avg, f(task::util_avg@dequeue))
This allows to remember how big a task has been reported by PELT in its
previous activations via f(task::util_avg@dequeue), which is the new
_task_util_est(struct task_struct*) function added by this patch.
If a task should change its behavior and it runs longer in a new
activation, after a certain time its util_est will just track the
original PELT signal (i.e. task::util_avg).
The estimated utilization of cfs_rq is defined only for root ones.
That's because the only sensible consumer of this signal are the
scheduler and schedutil when looking for the overall CPU utilization
due to FAIR tasks.
For this reason, the estimated utilization of a root cfs_rq is simply
defined as:
util_est(cfs_rq) = max(cfs_rq::util_avg, cfs_rq::util_est::enqueued)
where:
cfs_rq::util_est::enqueued = sum(_task_util_est(task))
for each RUNNABLE task on that root cfs_rq
It's worth noting that the estimated utilization is tracked only for
objects of interests, specifically:
- Tasks: to better support tasks placement decisions
- root cfs_rqs: to better support both tasks placement decisions as
well as frequencies selection
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-09 12:52:42 +03:00
SEQ_printf ( m , " .%-30s: %u \n " , " util_est_enqueued " ,
cfs_rq - > avg . util_est . enqueued ) ;
2017-05-08 17:51:41 +03:00
SEQ_printf ( m , " .%-30s: %ld \n " , " removed.load_avg " ,
cfs_rq - > removed . load_avg ) ;
SEQ_printf ( m , " .%-30s: %ld \n " , " removed.util_avg " ,
cfs_rq - > removed . util_avg ) ;
2020-02-24 12:52:18 +03:00
SEQ_printf ( m , " .%-30s: %ld \n " , " removed.runnable_avg " ,
cfs_rq - > removed . runnable_avg ) ;
2013-06-28 15:10:35 +04:00
# ifdef CONFIG_FAIR_GROUP_SCHED
sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-15 03:04:37 +03:00
SEQ_printf ( m , " .%-30s: %lu \n " , " tg_load_avg_contrib " ,
cfs_rq - > tg_load_avg_contrib ) ;
2013-06-28 15:10:35 +04:00
SEQ_printf ( m , " .%-30s: %ld \n " , " tg_load_avg " ,
atomic_long_read ( & cfs_rq - > tg - > load_avg ) ) ;
2008-06-27 15:41:14 +04:00
# endif
2013-06-28 15:10:35 +04:00
# endif
2013-10-16 22:16:32 +04:00
# ifdef CONFIG_CFS_BANDWIDTH
SEQ_printf ( m , " .%-30s: %d \n " , " throttled " ,
cfs_rq - > throttled ) ;
SEQ_printf ( m , " .%-30s: %d \n " , " throttle_count " ,
cfs_rq - > throttle_count ) ;
# endif
2010-11-16 02:47:00 +03:00
2013-06-28 15:10:35 +04:00
# ifdef CONFIG_FAIR_GROUP_SCHED
2008-11-10 19:04:09 +03:00
print_cfs_group_stats ( m , cpu , cfs_rq - > tg ) ;
2008-06-27 15:41:14 +04:00
# endif
2007-07-09 20:52:00 +04:00
}
2008-06-19 16:22:24 +04:00
void print_rt_rq ( struct seq_file * m , int cpu , struct rt_rq * rt_rq )
{
2011-01-11 13:11:54 +03:00
# ifdef CONFIG_RT_GROUP_SCHED
2018-03-19 21:35:55 +03:00
SEQ_printf ( m , " \n " ) ;
2021-04-15 22:54:26 +03:00
SEQ_printf_task_group_path ( m , rt_rq - > tg , " rt_rq[%d]:%s \n " , cpu ) ;
2011-01-11 13:11:54 +03:00
# else
2018-03-19 21:35:55 +03:00
SEQ_printf ( m , " \n " ) ;
SEQ_printf ( m , " rt_rq[%d]: \n " , cpu ) ;
2011-01-11 13:11:54 +03:00
# endif
2008-06-19 16:22:24 +04:00
# define P(x) \
SEQ_printf ( m , " .%-30s: %Ld \n " , # x , ( long long ) ( rt_rq - > x ) )
2017-06-26 18:07:14 +03:00
# define PU(x) \
SEQ_printf ( m , " .%-30s: %lu \n " , # x , ( unsigned long ) ( rt_rq - > x ) )
2008-06-19 16:22:24 +04:00
# define PN(x) \
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , # x , SPLIT_NS ( rt_rq - > x ) )
2017-06-26 18:07:14 +03:00
PU ( rt_nr_running ) ;
2008-06-19 16:22:24 +04:00
P ( rt_throttled ) ;
PN ( rt_time ) ;
PN ( rt_runtime ) ;
# undef PN
2017-06-26 18:07:14 +03:00
# undef PU
2008-06-19 16:22:24 +04:00
# undef P
}
2014-10-31 01:39:33 +03:00
void print_dl_rq ( struct seq_file * m , int cpu , struct dl_rq * dl_rq )
{
2016-02-23 00:26:52 +03:00
struct dl_bw * dl_bw ;
2018-03-19 21:35:55 +03:00
SEQ_printf ( m , " \n " ) ;
SEQ_printf ( m , " dl_rq[%d]: \n " , cpu ) ;
2017-06-26 18:07:14 +03:00
# define PU(x) \
SEQ_printf ( m , " .%-30s: %lu \n " , # x , ( unsigned long ) ( dl_rq - > x ) )
PU ( dl_nr_running ) ;
2016-02-23 00:26:52 +03:00
# ifdef CONFIG_SMP
dl_bw = & cpu_rq ( cpu ) - > rd - > dl_bw ;
# else
dl_bw = & dl_rq - > dl_bw ;
# endif
SEQ_printf ( m , " .%-30s: %lld \n " , " dl_bw->bw " , dl_bw - > bw ) ;
SEQ_printf ( m , " .%-30s: %lld \n " , " dl_bw->total_bw " , dl_bw - > total_bw ) ;
2017-06-26 18:07:14 +03:00
# undef PU
2014-10-31 01:39:33 +03:00
}
2007-08-09 13:16:51 +04:00
static void print_cpu ( struct seq_file * m , int cpu )
2007-07-09 20:52:00 +04:00
{
2009-06-17 17:20:55 +04:00
struct rq * rq = cpu_rq ( cpu ) ;
2007-07-09 20:52:00 +04:00
# ifdef CONFIG_X86
{
unsigned int freq = cpu_khz ? : 1 ;
2013-02-22 03:15:09 +04:00
SEQ_printf ( m , " cpu#%d, %u.%03u MHz \n " ,
2007-07-09 20:52:00 +04:00
cpu , freq / 1000 , ( freq % 1000 ) ) ;
}
# else
2013-02-22 03:15:09 +04:00
SEQ_printf ( m , " cpu#%d \n " , cpu ) ;
2007-07-09 20:52:00 +04:00
# endif
2012-05-14 16:34:00 +04:00
# define P(x) \
do { \
if ( sizeof ( rq - > x ) = = 4 ) \
2023-05-06 10:42:53 +03:00
SEQ_printf ( m , " .%-30s: %d \n " , # x , ( int ) ( rq - > x ) ) ; \
2012-05-14 16:34:00 +04:00
else \
SEQ_printf ( m , " .%-30s: %Ld \n " , # x , ( long long ) ( rq - > x ) ) ; \
} while ( 0 )
2007-10-15 19:00:08 +04:00
# define PN(x) \
SEQ_printf ( m , " .%-30s: %Ld.%06ld \n " , # x , SPLIT_NS ( rq - > x ) )
2007-07-09 20:52:00 +04:00
P ( nr_running ) ;
P ( nr_switches ) ;
P ( nr_uninterruptible ) ;
2007-10-15 19:00:08 +04:00
PN ( next_balance ) ;
2013-09-09 15:01:41 +04:00
SEQ_printf ( m , " .%-30s: %ld \n " , " curr->pid " , ( long ) ( task_pid_nr ( rq - > curr ) ) ) ;
2007-10-15 19:00:08 +04:00
PN ( clock ) ;
2015-01-05 13:18:12 +03:00
PN ( clock_task ) ;
2007-07-09 20:52:00 +04:00
# undef P
2007-10-15 19:00:08 +04:00
# undef PN
2007-07-09 20:52:00 +04:00
2009-11-04 19:53:50 +03:00
# ifdef CONFIG_SMP
2016-05-03 07:38:25 +03:00
# define P64(n) SEQ_printf(m, " .%-30s: %Ld\n", #n, rq->n);
2009-11-04 19:53:50 +03:00
P64 ( avg_idle ) ;
2014-01-23 14:39:54 +04:00
P64 ( max_idle_balance_cost ) ;
2016-05-03 07:38:25 +03:00
# undef P64
2009-11-04 19:53:50 +03:00
# endif
2008-11-10 12:46:32 +03:00
2016-06-17 20:43:26 +03:00
# define P(n) SEQ_printf(m, " .%-30s: %d\n", #n, schedstat_val(rq->n));
2016-02-05 12:08:36 +03:00
if ( schedstat_enabled ( ) ) {
P ( yld_count ) ;
P ( sched_count ) ;
P ( sched_goidle ) ;
P ( ttwu_count ) ;
P ( ttwu_local ) ;
}
2008-11-10 12:46:32 +03:00
# undef P
2016-06-17 20:43:26 +03:00
2007-08-09 13:16:47 +04:00
print_cfs_stats ( m , cpu ) ;
2008-06-19 16:22:24 +04:00
print_rt_stats ( m , cpu ) ;
2014-10-31 01:39:33 +03:00
print_dl_stats ( m , cpu ) ;
2007-07-09 20:52:00 +04:00
2007-08-09 13:16:51 +04:00
print_rq ( m , rq , cpu ) ;
2013-02-22 03:15:09 +04:00
SEQ_printf ( m , " \n " ) ;
2007-07-09 20:52:00 +04:00
}
2009-11-30 14:16:47 +03:00
static const char * sched_tunable_scaling_names [ ] = {
" none " ,
2018-11-28 18:23:50 +03:00
" logarithmic " ,
2009-11-30 14:16:47 +03:00
" linear "
} ;
2013-02-22 03:15:09 +04:00
static void sched_debug_header ( struct seq_file * m )
2007-07-09 20:52:00 +04:00
{
2010-11-19 23:11:09 +03:00
u64 ktime , sched_clk , cpu_clk ;
unsigned long flags ;
2007-07-09 20:52:00 +04:00
2010-11-19 23:11:09 +03:00
local_irq_save ( flags ) ;
ktime = ktime_to_ns ( ktime_get ( ) ) ;
sched_clk = sched_clock ( ) ;
cpu_clk = local_clock ( ) ;
local_irq_restore ( flags ) ;
2013-10-07 14:29:30 +04:00
SEQ_printf ( m , " Sched Debug Version: v0.11, %s %.*s \n " ,
2007-07-09 20:52:00 +04:00
init_utsname ( ) - > release ,
( int ) strcspn ( init_utsname ( ) - > version , " " ) ,
init_utsname ( ) - > version ) ;
2010-11-19 23:11:09 +03:00
# define P(x) \
SEQ_printf ( m , " %-40s: %Ld \n " , # x , ( long long ) ( x ) )
# define PN(x) \
SEQ_printf ( m , " %-40s: %Ld.%06ld \n " , # x , SPLIT_NS ( x ) )
PN ( ktime ) ;
PN ( sched_clk ) ;
PN ( cpu_clk ) ;
P ( jiffies ) ;
# ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
2013-11-28 22:38:42 +04:00
P ( sched_clock_stable ( ) ) ;
2010-11-19 23:11:09 +03:00
# endif
# undef PN
# undef P
SEQ_printf ( m , " \n " ) ;
SEQ_printf ( m , " sysctl_sched \n " ) ;
2007-07-09 20:52:00 +04:00
2007-10-15 19:00:10 +04:00
# define P(x) \
2007-10-15 19:00:10 +04:00
SEQ_printf ( m , " .%-40s: %Ld \n " , # x , ( long long ) ( x ) )
2007-10-15 19:00:10 +04:00
# define PN(x) \
2007-10-15 19:00:10 +04:00
SEQ_printf ( m , " .%-40s: %Ld.%06ld \n " , # x , SPLIT_NS ( x ) )
2023-05-31 14:58:48 +03:00
PN ( sysctl_sched_base_slice ) ;
2007-10-15 19:00:10 +04:00
P ( sysctl_sched_features ) ;
# undef PN
# undef P
2013-02-22 03:15:09 +04:00
SEQ_printf ( m , " .%-40s: %d (%s) \n " ,
" sysctl_sched_tunable_scaling " ,
2009-11-30 14:16:47 +03:00
sysctl_sched_tunable_scaling ,
sched_tunable_scaling_names [ sysctl_sched_tunable_scaling ] ) ;
2013-02-22 03:15:09 +04:00
SEQ_printf ( m , " \n " ) ;
}
2009-11-30 14:16:47 +03:00
2013-02-22 03:15:09 +04:00
static int sched_debug_show ( struct seq_file * m , void * v )
{
int cpu = ( unsigned long ) ( v - 2 ) ;
2007-07-09 20:52:00 +04:00
2013-02-22 03:15:09 +04:00
if ( cpu ! = - 1 )
print_cpu ( m , cpu ) ;
else
sched_debug_header ( m ) ;
2007-07-09 20:52:00 +04:00
return 0 ;
}
2011-10-25 12:00:11 +04:00
void sysrq_sched_debug_show ( void )
2007-07-09 20:52:00 +04:00
{
2013-02-22 03:15:09 +04:00
int cpu ;
sched_debug_header ( NULL ) ;
2019-12-26 11:52:24 +03:00
for_each_online_cpu ( cpu ) {
/*
* Need to reset softlockup watchdogs on all CPUs , because
* another CPU might be blocked waiting for us to process
* an IPI or stop_machine .
*/
touch_nmi_watchdog ( ) ;
touch_all_softlockup_watchdogs ( ) ;
2013-02-22 03:15:09 +04:00
print_cpu ( NULL , cpu ) ;
2019-12-26 11:52:24 +03:00
}
2013-02-22 03:15:09 +04:00
}
/*
2021-03-18 15:38:50 +03:00
* This iterator needs some explanation .
2013-02-22 03:15:09 +04:00
* It returns 1 for the header position .
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
* This means 2 is CPU 0.
* In a hotplugged system some CPUs , including CPU 0 , may be missing so we have
* to use cpumask_ * to iterate over the CPUs .
2013-02-22 03:15:09 +04:00
*/
static void * sched_debug_start ( struct seq_file * file , loff_t * offset )
{
unsigned long n = * offset ;
if ( n = = 0 )
return ( void * ) 1 ;
n - - ;
if ( n > 0 )
n = cpumask_next ( n - 1 , cpu_online_mask ) ;
else
n = cpumask_first ( cpu_online_mask ) ;
* offset = n + 1 ;
if ( n < nr_cpu_ids )
return ( void * ) ( unsigned long ) ( n + 2 ) ;
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
2013-02-22 03:15:09 +04:00
return NULL ;
}
static void * sched_debug_next ( struct seq_file * file , void * data , loff_t * offset )
{
( * offset ) + + ;
return sched_debug_start ( file , offset ) ;
}
static void sched_debug_stop ( struct seq_file * file , void * data )
{
}
static const struct seq_operations sched_debug_sops = {
sched: Clean up and harmonize the coding style of the scheduler code base
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 16:01:12 +03:00
. start = sched_debug_start ,
. next = sched_debug_next ,
. stop = sched_debug_stop ,
. show = sched_debug_show ,
2013-02-22 03:15:09 +04:00
} ;
2020-02-26 15:45:42 +03:00
# define __PS(S, F) SEQ_printf(m, "%-45s:%21Ld\n", S, (long long)(F))
# define __P(F) __PS(#F, F)
# define P(F) __PS(#F, p->F)
2021-06-02 17:58:08 +03:00
# define PM(F, M) __PS(#F, p->F & (M))
2020-02-26 15:45:42 +03:00
# define __PSN(S, F) SEQ_printf(m, "%-45s:%14Ld.%06ld\n", S, SPLIT_NS((long long)(F)))
# define __PN(F) __PSN(#F, F)
# define PN(F) __PSN(#F, p->F)
2013-10-07 14:29:30 +04:00
2015-06-25 20:21:43 +03:00
# ifdef CONFIG_NUMA_BALANCING
void print_numa_stats ( struct seq_file * m , int node , unsigned long tsf ,
unsigned long tpf , unsigned long gsf , unsigned long gpf )
{
SEQ_printf ( m , " numa_faults node=%d " , node ) ;
2018-06-20 20:02:47 +03:00
SEQ_printf ( m , " task_private=%lu task_shared=%lu " , tpf , tsf ) ;
SEQ_printf ( m , " group_private=%lu group_shared=%lu \n " , gpf , gsf ) ;
2015-06-25 20:21:43 +03:00
}
# endif
2013-10-07 14:29:30 +04:00
static void sched_show_numa ( struct task_struct * p , struct seq_file * m )
{
# ifdef CONFIG_NUMA_BALANCING
if ( p - > mm )
P ( mm - > numa_scan_seq ) ;
2015-06-25 20:21:43 +03:00
P ( numa_pages_migrated ) ;
P ( numa_preferred_nid ) ;
P ( total_numa_faults ) ;
SEQ_printf ( m , " current_node=%d, numa_group_id=%d \n " ,
task_node ( p ) , task_numa_group_id ( p ) ) ;
show_numa_stats ( p , m ) ;
2013-10-07 14:29:30 +04:00
# endif
}
2017-08-06 07:41:41 +03:00
void proc_sched_show_task ( struct task_struct * p , struct pid_namespace * ns ,
struct seq_file * m )
2007-07-09 20:52:00 +04:00
{
2007-10-15 19:00:18 +04:00
unsigned long nr_switches ;
2007-07-09 20:52:00 +04:00
2017-08-06 07:41:41 +03:00
SEQ_printf ( m , " %s (%d, #threads: %d) \n " , p - > comm , task_pid_nr_ns ( p , ns ) ,
2010-05-27 01:43:22 +04:00
get_nr_threads ( p ) ) ;
2007-10-15 19:00:18 +04:00
SEQ_printf ( m ,
2013-06-27 20:50:05 +04:00
" --------------------------------------------------------- "
" ---------- \n " ) ;
2020-02-26 15:45:42 +03:00
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
# define P_SCHEDSTAT(F) __PS(#F, schedstat_val(p->stats.F))
# define PN_SCHEDSTAT(F) __PSN(#F, schedstat_val(p->stats.F))
2007-07-09 20:52:00 +04:00
2007-10-15 19:00:08 +04:00
PN ( se . exec_start ) ;
PN ( se . vruntime ) ;
PN ( se . sum_exec_runtime ) ;
2007-08-02 19:41:40 +04:00
2007-10-15 19:00:18 +04:00
nr_switches = p - > nvcsw + p - > nivcsw ;
P ( se . nr_migrations ) ;
2016-02-05 12:08:36 +03:00
if ( schedstat_enabled ( ) ) {
2007-10-15 19:00:18 +04:00
u64 avg_atom , avg_per_cpu ;
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
PN_SCHEDSTAT ( sum_sleep_runtime ) ;
2021-09-05 17:35:43 +03:00
PN_SCHEDSTAT ( sum_block_runtime ) ;
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
PN_SCHEDSTAT ( wait_start ) ;
PN_SCHEDSTAT ( sleep_start ) ;
PN_SCHEDSTAT ( block_start ) ;
PN_SCHEDSTAT ( sleep_max ) ;
PN_SCHEDSTAT ( block_max ) ;
PN_SCHEDSTAT ( exec_max ) ;
PN_SCHEDSTAT ( slice_max ) ;
PN_SCHEDSTAT ( wait_max ) ;
PN_SCHEDSTAT ( wait_sum ) ;
P_SCHEDSTAT ( wait_count ) ;
PN_SCHEDSTAT ( iowait_sum ) ;
P_SCHEDSTAT ( iowait_count ) ;
P_SCHEDSTAT ( nr_migrations_cold ) ;
P_SCHEDSTAT ( nr_failed_migrations_affine ) ;
P_SCHEDSTAT ( nr_failed_migrations_running ) ;
P_SCHEDSTAT ( nr_failed_migrations_hot ) ;
P_SCHEDSTAT ( nr_forced_migrations ) ;
P_SCHEDSTAT ( nr_wakeups ) ;
P_SCHEDSTAT ( nr_wakeups_sync ) ;
P_SCHEDSTAT ( nr_wakeups_migrate ) ;
P_SCHEDSTAT ( nr_wakeups_local ) ;
P_SCHEDSTAT ( nr_wakeups_remote ) ;
P_SCHEDSTAT ( nr_wakeups_affine ) ;
P_SCHEDSTAT ( nr_wakeups_affine_attempts ) ;
P_SCHEDSTAT ( nr_wakeups_passive ) ;
P_SCHEDSTAT ( nr_wakeups_idle ) ;
2016-02-05 12:08:36 +03:00
2007-10-15 19:00:18 +04:00
avg_atom = p - > se . sum_exec_runtime ;
if ( nr_switches )
2014-06-14 17:00:09 +04:00
avg_atom = div64_ul ( avg_atom , nr_switches ) ;
2007-10-15 19:00:18 +04:00
else
avg_atom = - 1LL ;
avg_per_cpu = p - > se . sum_exec_runtime ;
2007-11-28 17:52:56 +03:00
if ( p - > se . nr_migrations ) {
2008-05-01 15:34:28 +04:00
avg_per_cpu = div64_u64 ( avg_per_cpu ,
p - > se . nr_migrations ) ;
2007-11-28 17:52:56 +03:00
} else {
2007-10-15 19:00:18 +04:00
avg_per_cpu = - 1LL ;
2007-11-28 17:52:56 +03:00
}
2007-10-15 19:00:18 +04:00
__PN ( avg_atom ) ;
__PN ( avg_per_cpu ) ;
2021-10-18 23:34:28 +03:00
# ifdef CONFIG_SCHED_CORE
PN_SCHEDSTAT ( core_forceidle_sum ) ;
# endif
2007-10-15 19:00:18 +04:00
}
2016-06-17 20:43:26 +03:00
2007-10-15 19:00:18 +04:00
__P ( nr_switches ) ;
2020-02-26 15:45:42 +03:00
__PS ( " nr_voluntary_switches " , p - > nvcsw ) ;
__PS ( " nr_involuntary_switches " , p - > nivcsw ) ;
2007-10-15 19:00:18 +04:00
2007-07-09 20:52:00 +04:00
P ( se . load . weight ) ;
2013-06-28 15:10:35 +04:00
# ifdef CONFIG_SMP
sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-15 03:04:37 +03:00
P ( se . avg . load_sum ) ;
2020-02-24 12:52:18 +03:00
P ( se . avg . runnable_sum ) ;
sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-15 03:04:37 +03:00
P ( se . avg . util_sum ) ;
P ( se . avg . load_avg ) ;
2020-02-24 12:52:18 +03:00
P ( se . avg . runnable_avg ) ;
sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-15 03:04:37 +03:00
P ( se . avg . util_avg ) ;
P ( se . avg . last_update_time ) ;
sched/fair: Add util_est on top of PELT
The util_avg signal computed by PELT is too variable for some use-cases.
For example, a big task waking up after a long sleep period will have its
utilization almost completely decayed. This introduces some latency before
schedutil will be able to pick the best frequency to run a task.
The same issue can affect task placement. Indeed, since the task
utilization is already decayed at wakeup, when the task is enqueued in a
CPU, this can result in a CPU running a big task as being temporarily
represented as being almost empty. This leads to a race condition where
other tasks can be potentially allocated on a CPU which just started to run
a big task which slept for a relatively long period.
Moreover, the PELT utilization of a task can be updated every [ms], thus
making it a continuously changing value for certain longer running
tasks. This means that the instantaneous PELT utilization of a RUNNING
task is not really meaningful to properly support scheduler decisions.
For all these reasons, a more stable signal can do a better job of
representing the expected/estimated utilization of a task/cfs_rq.
Such a signal can be easily created on top of PELT by still using it as
an estimator which produces values to be aggregated on meaningful
events.
This patch adds a simple implementation of util_est, a new signal built on
top of PELT's util_avg where:
util_est(task) = max(task::util_avg, f(task::util_avg@dequeue))
This allows to remember how big a task has been reported by PELT in its
previous activations via f(task::util_avg@dequeue), which is the new
_task_util_est(struct task_struct*) function added by this patch.
If a task should change its behavior and it runs longer in a new
activation, after a certain time its util_est will just track the
original PELT signal (i.e. task::util_avg).
The estimated utilization of cfs_rq is defined only for root ones.
That's because the only sensible consumer of this signal are the
scheduler and schedutil when looking for the overall CPU utilization
due to FAIR tasks.
For this reason, the estimated utilization of a root cfs_rq is simply
defined as:
util_est(cfs_rq) = max(cfs_rq::util_avg, cfs_rq::util_est::enqueued)
where:
cfs_rq::util_est::enqueued = sum(_task_util_est(task))
for each RUNNABLE task on that root cfs_rq
It's worth noting that the estimated utilization is tracked only for
objects of interests, specifically:
- Tasks: to better support tasks placement decisions
- root cfs_rqs: to better support both tasks placement decisions as
well as frequencies selection
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-09 12:52:42 +03:00
P ( se . avg . util_est . ewma ) ;
2021-06-02 17:58:08 +03:00
PM ( se . avg . util_est . enqueued , ~ UTIL_AVG_UNCHANGED ) ;
2020-02-26 15:45:43 +03:00
# endif
# ifdef CONFIG_UCLAMP_TASK
2020-05-10 15:56:41 +03:00
__PS ( " uclamp.min " , p - > uclamp_req [ UCLAMP_MIN ] . value ) ;
__PS ( " uclamp.max " , p - > uclamp_req [ UCLAMP_MAX ] . value ) ;
2020-02-26 15:45:43 +03:00
__PS ( " effective uclamp.min " , uclamp_eff_value ( p , UCLAMP_MIN ) ) ;
__PS ( " effective uclamp.max " , uclamp_eff_value ( p , UCLAMP_MAX ) ) ;
2013-06-25 12:03:36 +04:00
# endif
2007-07-09 20:52:00 +04:00
P ( policy ) ;
P ( prio ) ;
2018-11-05 14:21:55 +03:00
if ( task_has_dl_policy ( p ) ) {
2016-10-26 12:17:17 +03:00
P ( dl . runtime ) ;
P ( dl . deadline ) ;
}
2016-06-17 20:43:26 +03:00
# undef PN_SCHEDSTAT
# undef P_SCHEDSTAT
2007-07-09 20:52:00 +04:00
{
2008-11-16 10:07:15 +03:00
unsigned int this_cpu = raw_smp_processor_id ( ) ;
2007-07-09 20:52:00 +04:00
u64 t0 , t1 ;
2008-11-16 10:07:15 +03:00
t0 = cpu_clock ( this_cpu ) ;
t1 = cpu_clock ( this_cpu ) ;
2020-02-26 15:45:42 +03:00
__PS ( " clock-delta " , t1 - t0 ) ;
2007-07-09 20:52:00 +04:00
}
2013-10-07 14:29:30 +04:00
sched_show_numa ( p , m ) ;
2007-07-09 20:52:00 +04:00
}
void proc_sched_set_task ( struct task_struct * p )
{
2007-08-02 19:41:40 +04:00
# ifdef CONFIG_SCHEDSTATS
sched: Make struct sched_statistics independent of fair sched class
If we want to use the schedstats facility to trace other sched classes, we
should make it independent of fair sched class. The struct sched_statistics
is the schedular statistics of a task_struct or a task_group. So we can
move it into struct task_struct and struct task_group to achieve the goal.
After the patch, schestats are orgnized as follows,
struct task_struct {
...
struct sched_entity se;
struct sched_rt_entity rt;
struct sched_dl_entity dl;
...
struct sched_statistics stats;
...
};
Regarding the task group, schedstats is only supported for fair group
sched, and a new struct sched_entity_stats is introduced, suggested by
Peter -
struct sched_entity_stats {
struct sched_entity se;
struct sched_statistics stats;
} __no_randomize_layout;
Then with the se in a task_group, we can easily get the stats.
The sched_statistics members may be frequently modified when schedstats is
enabled, in order to avoid impacting on random data which may in the same
cacheline with them, the struct sched_statistics is defined as cacheline
aligned.
As this patch changes the core struct of scheduler, so I verified the
performance it may impact on the scheduler with 'perf bench sched
pipe', suggested by Mel. Below is the result, in which all the values
are in usecs/op.
Before After
kernel.sched_schedstats=0 5.2~5.4 5.2~5.4
kernel.sched_schedstats=1 5.3~5.5 5.3~5.5
[These data is a little difference with the earlier version, that is
because my old test machine is destroyed so I have to use a new
different test machine.]
Almost no impact on the sched performance.
No functional change.
[lkp@intel.com: reported build failure in earlier version]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20210905143547.4668-3-laoar.shao@gmail.com
2021-09-05 17:35:41 +03:00
memset ( & p - > stats , 0 , sizeof ( p - > stats ) ) ;
2007-08-02 19:41:40 +04:00
# endif
2007-07-09 20:52:00 +04:00
}
2021-04-17 00:29:36 +03:00
void resched_latency_warn ( int cpu , u64 latency )
{
static DEFINE_RATELIMIT_STATE ( latency_check_ratelimit , 60 * 60 * HZ , 1 ) ;
WARN ( __ratelimit ( & latency_check_ratelimit ) ,
" sched: CPU %d need_resched set for > %llu ns (%d ticks) "
" without schedule \n " ,
cpu , latency , cpu_rq ( cpu ) - > ticks_without_resched ) ;
}