linux/kernel/sched
Matt Fleming cb42c9a3eb sched/core: Add debugging code to catch missing update_rq_clock() calls
There's no diagnostic checks for figuring out when we've accidentally
missed update_rq_clock() calls. Let's add some by piggybacking on the
rq_*pin_lock() wrappers.

The idea behind the diagnostic checks is that upon pining rq lock the
rq clock should be updated, via update_rq_clock(), before anybody
reads the clock with rq_clock() or rq_clock_task().

The exception to this rule is when updates have explicitly been
disabled with the rq_clock_skip_update() optimisation.

There are some functions that only unpin the rq lock in order to grab
some other lock and avoid deadlock. In that case we don't need to
update the clock again and the previous diagnostic state can be
carried over in rq_repin_lock() by saving the state in the rq_flags
context.

Since this patch adds a new clock update flag and some already exist
in rq::clock_skip_update, that field has now been renamed. An attempt
has been made to keep the flag manipulation code small and fast since
it's used in the heart of the __schedule() fast path.

For the !CONFIG_SCHED_DEBUG case the only object code change (other
than addresses) is the following change to reset RQCF_ACT_SKIP inside
of __schedule(),

  -       c7 83 38 09 00 00 00    movl   $0x0,0x938(%rbx)
  -       00 00 00
  +       83 a3 38 09 00 00 fc    andl   $0xfffffffc,0x938(%rbx)

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-8-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:29:35 +01:00
..
auto_group.c sched/autogroup: Fix 64-bit kernel nice level adjustment 2016-11-24 05:45:02 +01:00
auto_group.h sched, timer: Convert usages of ACCESS_ONCE() in the scheduler to READ_ONCE()/WRITE_ONCE() 2015-05-08 12:11:32 +02:00
clock.c sched/clock: Make local_clock()/cpu_clock() inline 2016-04-13 12:25:22 +02:00
completion.c sched/completion: Serialize completion_done() with complete() 2015-02-18 14:27:40 +01:00
core.c sched/core: Add debugging code to catch missing update_rq_clock() calls 2017-01-14 11:29:35 +01:00
cpuacct.c sched/cpuacct: Avoid %lld seq_printf warning 2016-11-16 10:29:03 +01:00
cpuacct.h sched/cpuacct: Simplify the cpuacct code 2016-03-21 11:00:28 +01:00
cpudeadline.c sched/deadline: Split cpudl_set() into cpudl_set() and cpudl_clear() 2016-09-05 13:29:43 +02:00
cpudeadline.h sched/deadline: Split cpudl_set() into cpudl_set() and cpudl_clear() 2016-09-05 13:29:43 +02:00
cpufreq_schedutil.c cpufreq: schedutil: Rectify comment in sugov_irq_work() function 2016-11-24 21:50:59 +01:00
cpufreq.c cpufreq / sched: Pass flags to cpufreq_update_util() 2016-08-16 22:14:55 +02:00
cpupri.c sched/core: Use tsk_cpus_allowed() instead of accessing ->cpus_allowed 2016-05-12 09:55:35 +02:00
cpupri.h sched/cpupri: Remove unnecessary definitions in cpupri.h 2014-11-16 10:58:59 +01:00
cputime.c sched/cputime: Rename vtime_account_user() to vtime_flush() 2017-01-14 09:54:13 +01:00
deadline.c sched/core: Add wrappers for lockdep_(un)pin_lock() 2017-01-14 11:29:30 +01:00
debug.c Merge branch 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-10-14 12:18:50 -07:00
fair.c sched/core: Add missing update_rq_clock() call for task_hot() 2017-01-14 11:29:34 +01:00
features.h sched/fair: Convert arch_scale_cpu_capacity() from weak function to #define 2015-09-13 09:52:55 +02:00
idle_task.c sched/core: Add wrappers for lockdep_(un)pin_lock() 2017-01-14 11:29:30 +01:00
idle.c sched/idle: Add support for tasks that inject idle 2016-11-29 14:02:21 +01:00
loadavg.c sched/core: Correct off by one bug in load migration calculation 2016-07-13 14:58:20 +02:00
Makefile cpufreq: schedutil: New governor based on scheduler utilization data 2016-04-02 01:09:12 +02:00
rt.c sched/core: Add wrappers for lockdep_(un)pin_lock() 2017-01-14 11:29:30 +01:00
sched.h sched/core: Add debugging code to catch missing update_rq_clock() calls 2017-01-14 11:29:35 +01:00
stats.c sched: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
stats.h sched/debug: Rename 'schedstat_val()' -> 'schedstat_val_or_zero()' 2016-09-05 13:29:46 +02:00
stop_task.c sched/core: Add wrappers for lockdep_(un)pin_lock() 2017-01-14 11:29:30 +01:00
swait.c wait.[ch]: Introduce the simple waitqueue (swait) implementation 2016-02-25 11:27:16 +01:00
wait.c mm: remove per-zone hashtable of bitlock waitqueues 2016-10-27 09:27:57 -07:00