Messages in this thread | | | Date | Mon, 2 Nov 2015 17:10:16 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v4 2/2] sched: consider missed ticks in full NOHZ |
| |
On Wed, Oct 14, 2015 at 06:47:36PM +0900, byungchul.park@lge.com wrote: > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -4428,7 +4428,7 @@ static void update_idle_cpu_load(struct rq *this_rq)
So if one were to read the comment above update_idle_cpu_load() one would find there's a problem with jiffy based accounting.
> /* > * 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)
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 7c7ec45..515edf3 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c
> -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();
And we could solve all that nicely if we pull up the hrtimer_forward() result from tick_nohz_restart(), that way we have the actual number of ticks lost on this cpu, and no need to start guessing about it.
Hmm?
| |