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sched/fair: Consider missed ticks in NOHZ_FULL in update_cpu_load_nohz() 

Usually the tick can be stopped for an idle CPU in NOHZ. However in NOHZ_FULL
mode, a non-idle CPU's tick can also be stopped. However, update_cpu_load_nohz()
does not consider the case a non-idle CPU's tick has been stopped at all.

This patch makes the update_cpu_load_nohz() know if the calling path comes
from NOHZ_FULL or idle NOHZ.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
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>
Link: http://lkml.kernel.org/r/1447115762-19734-3-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Byungchul Park 2015-11-10 09:36:02 +09:00 committed by Ingo Molnar
parent 5954327548
commit 525705d15e
3 changed files with 12 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/sched.h
View File

@ -177,9 +177,9 @@ extern void get_iowait_load(unsigned long *nr_waiters, unsigned long *load);
extern void calc_global_load(unsigned long ticks);
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
extern void update_cpu_load_nohz(void);
extern void update_cpu_load_nohz(int active);
#else
static inline void update_cpu_load_nohz(void) { }
static inline void update_cpu_load_nohz(int active) { }
#endif
extern unsigned long get_parent_ip(unsigned long addr);

10
kernel/sched/fair.c
View File

@ -4397,10 +4397,11 @@ static void update_idle_cpu_load(struct rq *this_rq)
/*
* Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
*/
void update_cpu_load_nohz(void)
void update_cpu_load_nohz(int active)
{
struct rq *this_rq = this_rq();
unsigned long curr_jiffies = READ_ONCE(jiffies);
unsigned long load = active ? weighted_cpuload(cpu_of(this_rq)) : 0;
unsigned long pending_updates;
if (curr_jiffies == this_rq->last_load_update_tick)
@ -4411,10 +4412,11 @@ void update_cpu_load_nohz(void)
if (pending_updates) {
this_rq->last_load_update_tick = curr_jiffies;
/*
* We were idle, this means load 0, the current load might be
* !0 due to remote wakeups and the sort.
* In the regular NOHZ case, we were idle, this means load 0.
* In the NOHZ_FULL case, we were non-idle, we should consider
* its weighted load.
*/
__update_cpu_load(this_rq, 0, pending_updates, 0);
__update_cpu_load(this_rq, load, pending_updates, active);
}
raw_spin_unlock(&this_rq->lock);
}

8
kernel/time/tick-sched.c
View File

@ -694,11 +694,11 @@ out:
return tick;
}
static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now, int active)
{
/* Update jiffies first */
tick_do_update_jiffies64(now);
update_cpu_load_nohz();
update_cpu_load_nohz(active);
calc_load_exit_idle();
touch_softlockup_watchdog();
@ -725,7 +725,7 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts)
if (can_stop_full_tick())
tick_nohz_stop_sched_tick(ts, ktime_get(), cpu);
else if (ts->tick_stopped)
tick_nohz_restart_sched_tick(ts, ktime_get());
tick_nohz_restart_sched_tick(ts, ktime_get(), 1);
#endif
}
@ -916,7 +916,7 @@ void tick_nohz_idle_exit(void)
tick_nohz_stop_idle(ts, now);
if (ts->tick_stopped) {
tick_nohz_restart_sched_tick(ts, now);
tick_nohz_restart_sched_tick(ts, now, 0);
tick_nohz_account_idle_ticks(ts);
}