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Date: Mon, 23 Nov 2015 11:32:14 +0900 From: Byungchul Park <byungchul.park@....com> To: Peter Zijlstra <peterz@...radead.org> Cc: mingo@...nel.org, linux-kernel@...r.kernel.org, efault@....de, tglx@...utronix.de, fweisbec@...il.com Subject: Re: [PATCH v5 2/2] sched: make update_cpu_load_nohz() consider missed ticks in NOHZ_FULL On Fri, Nov 20, 2015 at 02:19:55PM +0100, Peter Zijlstra wrote: > On Tue, Nov 10, 2015 at 09:36:02AM +0900, byungchul.park@....com wrote: > > +++ b/kernel/sched/fair.c > > @@ -4419,10 +4419,11 @@ 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) > > @@ -4433,10 +4434,11 @@ 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); > > } > > Bah, so I did all the work to get the actual number of lost ticks in > there, only to _then_ find out that's mostly pointless :-) > > The problem is update_idle_cpu_load() is called while idle (from another > CPU), so it still needs the whole jiffy based thing. > > So I'll take this patch for now. Thanks. Thank you. Byungchul > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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