Messages in this thread | | | Date | Wed, 26 May 2021 14:15:31 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched: fair: don't depend on wake_wide if waker and wakee are already in same LLC |
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$subject is weird; sched/fair: is the right tag, and then start with a capital letter.
On Wed, May 26, 2021 at 09:10:57PM +1200, Barry Song wrote: > when waker and wakee are already in the same LLC, it is pointless to worry > about the competition caused by pulling wakee to waker's LLC domain.
But there's more than LLC.
> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> > --- > kernel/sched/fair.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 3248e24a90b0..cfb1bd47acc3 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6795,7 +6795,15 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags) > new_cpu = prev_cpu; > } > > - want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, p->cpus_ptr); > + /* > + * we use wake_wide to make smarter pull and avoid cruel > + * competition because of jam-packed tasks in waker's LLC > + * domain. But if waker and wakee have been already in > + * same LLC domain, it seems it is pointless to depend > + * on wake_wide > + */ > + want_affine = (cpus_share_cache(cpu, prev_cpu) || !wake_wide(p)) && > + cpumask_test_cpu(cpu, p->cpus_ptr); > }
And no supportive numbers...
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