Cheng Jian 54b933c6c9 sched/idle: Micro-optimize the idle loop ...

Move the loop-invariant calculation of 'cpu' in do_idle() out of the loop body,
because the current CPU is always constant.

This improves the generated code both on x86-64 and ARM64:

x86-64:

Before patch (execution in loop):
	864:       0f ae e8                lfence
	867:       65 8b 05 c2 38 f1 7e    mov %gs:0x7ef138c2(%rip),%eax
	86e:       89 c0                   mov %eax,%eax
	870:       48 0f a3 05 68 19 08    bt  %rax,0x1081968(%rip)
	877:	   01

After patch (execution in loop):
	872:       0f ae e8                lfence
	875:       4c 0f a3 25 63 19 08    bt  %r12,0x1081963(%rip)
	87c:       01

ARM64:

Before patch (execution in loop):
	c58:       d5033d9f        dsb     ld
	c5c:       d538d080        mrs     x0, tpidr_el1
	c60:       b8606a61        ldr     w1, [x19,x0]
	c64:       1100fc20        add     w0, w1, #0x3f
	c68:       7100003f        cmp     w1, #0x0
	c6c:       1a81b000        csel    w0, w0, w1, lt
	c70:       13067c00        asr     w0, w0, #6
	c74:       93407c00        sxtw    x0, w0
	c78:       f8607a80        ldr     x0, [x20,x0,lsl #3]
	c7c:       9ac12401        lsr     x1, x0, x1
	c80:       36000581        tbz     w1, #0, d30 <do_idle+0x128>

After patch (execution in loop):
	c84:       d5033d9f        dsb     ld
	c88:       f9400260        ldr     x0, [x19]
	c8c:       ea14001f        tst     x0, x20
	c90:       54000580        b.eq    d40 <do_idle+0x138>

Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
[ Rewrote the title and the changelog. ]
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: huawei.libin@huawei.com
Cc: xiexiuqi@huawei.com
Link: http://lkml.kernel.org/r/1508930907-107755-1-git-send-email-cj.chengjian@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2017-10-26 08:31:29 +02:00

..

bpf

Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf

2017-10-09 10:39:52 -07:00

cgroup

cgroup: Reinit cgroup_taskset structure before cgroup_migrate_execute() returns

2017-09-22 08:14:45 -07:00

configs

ANDROID: binder: add hwbinder,vndbinder to BINDER_DEVICES.

2017-08-22 18:43:23 -07:00

debug

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>

2017-03-02 08:42:34 +01:00

events

perf/aux: Only update ->aux_wakeup in non-overwrite mode

2017-09-29 10:06:45 +02:00

gcov

gcov: support GCC 7.1

2017-05-12 15:57:15 -07:00

irq

irq/generic-chip: Don't replace domain's name

2017-09-28 12:18:59 +02:00

livepatch

livepatch: Fix stacking of patches with respect to RCU

2017-06-20 10:42:19 +02:00

locking

locking/rwsem-xadd: Fix missed wakeup due to reordering of load

2017-09-29 10:10:20 +02:00

power

PM / s2idle: Invoke the ->wake() platform callback earlier

2017-09-29 01:26:13 +02:00

printk

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk

2017-09-07 21:00:52 -07:00

rcu

Two updates.

2017-10-04 08:34:01 -07:00

sched

sched/idle: Micro-optimize the idle loop

2017-10-26 08:31:29 +02:00

time

sched/idle: Move quiet_vmstate() into the NOHZ code

2017-10-10 11:43:29 +02:00

trace

sched/debug: Rename task-state printing helpers

2017-10-10 11:43:29 +02:00

.gitignore

…

acct.c

fs: make the buf argument to __kernel_write a void pointer

2017-09-04 19:05:15 -04:00

async.c

async: Adjust system_state checks

2017-05-23 10:01:37 +02:00

audit_fsnotify.c

Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2017-05-03 11:05:15 -07:00

audit_tree.c

Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2017-05-03 11:05:15 -07:00

audit_watch.c

audit/stable-4.13 PR 20170816

2017-08-16 16:48:34 -07:00

audit.c

audit: update the function comments

2017-09-05 09:46:59 -04:00

audit.h

ipc: mqueue: Replace timespec with timespec64

2017-09-03 20:21:24 -04:00

auditfilter.c

audit: kernel generated netlink traffic should have a portid of 0

2017-05-02 10:16:05 -04:00

auditsc.c

Merge branch 'work.ipc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2017-09-14 17:37:26 -07:00

backtracetest.c

…

bounds.c

…

capability.c

capability: export has_capability

2017-01-12 07:01:56 -07:00

compat.c

semtimedop(): move compat to native

2017-07-15 20:46:47 -04:00

configs.c

…

context_tracking.c

…

cpu_pm.c

PM / CPU: replace raw_notifier with atomic_notifier

2017-07-31 13:09:49 +02:00

cpu.c

Merge branch 'core-watchdog-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-10-06 08:36:41 -07:00

crash_core.c

kdump: protect vmcoreinfo data under the crash memory

2017-07-12 16:26:00 -07:00

crash_dump.c

…

cred.c

doc: ReSTify credentials.txt

2017-05-18 10:30:19 -06:00

delayacct.c

sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>

2017-03-02 08:42:39 +01:00

dma.c

…

elfcore.c

…

exec_domain.c

…

exit.c

fix infoleak in waitid(2)

2017-09-29 13:43:15 -04:00

extable.c

extable: Enable RCU if it is not watching in kernel_text_address()

2017-09-23 16:50:20 -04:00

fork.c

android: binder: drop lru lock in isolate callback

2017-10-03 17:54:24 -07:00

freezer.c

…

futex_compat.c

…

futex.c

futex: Fix pi_state->owner serialization

2017-09-25 16:37:11 +02:00

groups.c

kernel/groups.c: use sort library function

2017-07-10 16:32:34 -07:00

hung_task.c

kernel/hung_task.c: defer showing held locks

2017-05-08 17:15:10 -07:00

irq_work.c

…

jump_label.c

jump_label: Provide hotplug context variants

2017-08-10 12:28:59 +02:00

kallsyms.c

kernel/kallsyms.c: replace all_var with IS_ENABLED(CONFIG_KALLSYMS_ALL)

2017-07-10 16:32:34 -07:00

kcmp.c

kernel/kcmp.c: drop branch leftover typo

2017-10-03 17:54:25 -07:00

Kconfig.freezer

…

Kconfig.hz

…

Kconfig.locks

…

Kconfig.preempt

…

kcov.c

kcov: support compat processes

2017-09-08 18:26:51 -07:00

kexec_core.c

x86/mm, kexec: Allow kexec to be used with SME

2017-07-18 11:38:04 +02:00

kexec_file.c

kexec_file: adjust declaration of kexec_purgatory

2017-07-12 16:26:02 -07:00

kexec_internal.h

kexec_file: adjust declaration of kexec_purgatory

2017-07-12 16:26:02 -07:00

kexec.c

kdump: protect vmcoreinfo data under the crash memory

2017-07-12 16:26:00 -07:00

kmod.c

kmod: move #ifdef CONFIG_MODULES wrapper to Makefile

2017-09-08 18:26:51 -07:00

kprobes.c

kprobes: Ensure that jprobe probepoints are at function entry

2017-07-08 11:05:35 +02:00

ksysfs.c

kexec: move vmcoreinfo out of the kernel's .bss section

2017-07-12 16:25:59 -07:00

kthread.c

kernel/kthread.c: kthread_worker: don't hog the cpu

2017-08-31 16:33:15 -07:00

latencytop.c

sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>

2017-03-02 08:42:39 +01:00

Makefile

kmod: move #ifdef CONFIG_MODULES wrapper to Makefile

2017-09-08 18:26:51 -07:00

memremap.c

memremap: add scheduling point to devm_memremap_pages

2017-10-03 17:54:25 -07:00

module_signing.c

…

module-internal.h

…

module.c

module: fix ddebug_remove_module()

2017-07-25 15:08:32 +02:00

notifier.c

kernel/notifier.c: simplify expression

2017-02-24 17:46:56 -08:00

nsproxy.c

perf: Add PERF_RECORD_NAMESPACES to include namespaces related info

2017-03-13 15:57:41 -03:00

padata.c

padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata()

2017-05-26 10:10:37 +02:00

panic.c

locking/refcounts, x86/asm: Implement fast refcount overflow protection

2017-08-17 10:40:26 +02:00

params.c

kernel/params.c: improve STANDARD_PARAM_DEF readability

2017-10-03 17:54:26 -07:00

pid_namespace.c

userns,pidns: Verify the userns for new pid namespaces

2017-07-20 07:43:58 -05:00

pid.c

pids: make task_tgid_nr_ns() safe

2017-08-21 12:47:31 -07:00

profile.c

sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>

2017-03-02 08:42:39 +01:00

ptrace.c

signal: Remove kernel interal si_code magic

2017-07-24 14:30:28 -05:00

range.c

…

reboot.c

…

relay.c

Merge branch 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2017-05-02 11:38:06 -07:00

resource.c

…

seccomp.c

seccomp: fix the usage of get/put_seccomp_filter() in seccomp_get_filter()

2017-09-27 22:51:12 -07:00

signal.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2017-09-11 18:34:47 -07:00

smp.c

treewide: make "nr_cpu_ids" unsigned

2017-09-08 18:26:48 -07:00

smpboot.c

watchdog/core, powerpc: Lock cpus across reconfiguration

2017-10-04 10:53:54 +02:00

smpboot.h

…

softirq.c

sched/core: Remove 'task' parameter and rename tsk_restore_flags() to current_restore_flags()

2017-04-11 09:06:32 +02:00

stacktrace.c

stacktrace/x86: add function for detecting reliable stack traces

2017-03-08 09:18:02 +01:00

stop_machine.c

stop_machine: Provide stop_machine_cpuslocked()

2017-05-26 10:10:36 +02:00

sys_ni.c

…

sys.c

prctl: Allow local CAP_SYS_ADMIN changing exe_file

2017-07-20 07:46:07 -05:00

sysctl_binary.c

fs: fix kernel_write prototype

2017-09-04 19:05:15 -04:00

sysctl.c

Merge branch 'core-watchdog-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-10-06 08:36:41 -07:00

task_work.c

task_work: Replace spin_unlock_wait() with lock/unlock pair

2017-07-25 10:08:58 -07:00

taskstats.c

taskstats: add e/u/stime for TGID command

2017-05-08 17:15:12 -07:00

test_kprobes.c

…

torture.c

torture: Fix typo suppressing CPU-hotplug statistics

2017-07-25 13:04:45 -07:00

tracepoint.c

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>

2017-03-02 08:42:35 +01:00

tsacct.c

sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>

2017-03-02 08:42:39 +01:00

ucount.c

ucount: Remove the atomicity from ucount->count

2017-03-06 15:26:37 -06:00

uid16.c

sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h>

2017-03-02 08:42:31 +01:00

umh.c

kmod: split out umh code into its own file

2017-09-08 18:26:50 -07:00

up.c

smp: Avoid using two cache lines for struct call_single_data

2017-08-29 15:14:38 +02:00

user_namespace.c

userns,pidns: Verify the userns for new pid namespaces

2017-07-20 07:43:58 -05:00

user-return-notifier.c

…

user.c

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h>

2017-03-02 08:42:29 +01:00

utsname_sysctl.c

sched/headers: Remove <linux/rwsem.h> from <linux/sched.h>

2017-03-03 01:45:36 +01:00

utsname.c

sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h>

2017-03-02 08:42:38 +01:00

watchdog_hld.c

watchdog/hardlockup/perf: Fix spelling mistake: "permanetely" -> "permanently"

2017-09-28 12:24:54 +02:00

watchdog.c

watchdog/core: Put softlockup_threads_initialized under ifdef guard

2017-10-04 11:30:50 +02:00

workqueue_internal.h

…

workqueue.c

Merge branch 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2017-09-06 21:59:31 -07:00