Messages in this thread | | | Date | Wed, 6 May 2020 11:28:56 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [patch V4 part 1 03/36] sched: Clean up scheduler_ipi() |
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On Wed, May 06, 2020 at 05:33:00PM +0200, Peter Zijlstra wrote: > On Wed, May 06, 2020 at 02:37:19PM +0200, Alexandre Chartre wrote: > > On 5/5/20 3:16 PM, Thomas Gleixner wrote: > > > @@ -650,6 +655,16 @@ static inline bool got_nohz_idle_kick(vo > > > return false; > > > } > > > +static void nohz_csd_func(void *info) > > > +{ > > > + struct rq *rq = info; > > > + > > > + if (got_nohz_idle_kick()) { > > > + rq->idle_balance = 1; > > > + raise_softirq_irqoff(SCHED_SOFTIRQ); > > > + } > > > +} > > > + > > > #else /* CONFIG_NO_HZ_COMMON */ > > > static inline bool got_nohz_idle_kick(void) > > > > #ifdef CONFIG_NO_HZ_COMMON > > > rq->last_blocked_load_update_tick = jiffies; > > > atomic_set(&rq->nohz_flags, 0); > > > + > > > + rq_csd_init(rq, &rq->nohz_csd, nohz_csd_func); > > > #endif > > > #endif /* CONFIG_SMP */ > > > hrtick_rq_init(rq); > > > --- a/kernel/sched/fair.c > > > +++ b/kernel/sched/fair.c > > > @@ -10009,12 +10009,11 @@ static void kick_ilb(unsigned int flags) > > > return; > > > /* > > > - * Use smp_send_reschedule() instead of resched_cpu(). > > > - * This way we generate a sched IPI on the target CPU which > > > + * This way we generate an IPI on the target CPU which > > > * is idle. And the softirq performing nohz idle load balance > > > * will be run before returning from the IPI. > > > */ > > > - smp_send_reschedule(ilb_cpu); > > > + smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->wake_csd); > > > > This should be nohz_csd instead of wake_csd, no? I.e.: > > > > smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd); > > You figured correctly. Thanks!
And this does get rid of the smp_call_function splats I was seeing earlier, thank you!
I still see warnings of the form "leave instruction with modified stack frame" from older complilers and of the form "undefined stack state" from newer compilers. I am running stock objtool versions, so I am guessing that this is at least one reason for these warnings.
Thanx, Paul
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