From: Mel Gorman <mgorman@techsingularity.net>
To: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
yangyicong <yangyicong@huawei.com>
Subject: Re: [PATCH 7/9] sched/fair: Enforce proportional scan limits when scanning for an idle core
Date: Wed, 4 Aug 2021 11:22:36 +0100 [thread overview]
Message-ID: <20210804102236.GB6464@techsingularity.net> (raw)
In-Reply-To: <58167022b9074ed9951b09ab6ba1983e@hisilicon.com>
On Mon, Aug 02, 2021 at 10:52:01AM +0000, Song Bao Hua (Barry Song) wrote:
> > @@ -6265,30 +6265,35 @@ static int select_idle_cpu(struct task_struct *p, struct
> > sched_domain *sd, bool
> > if (has_idle_core) {
> > i = select_idle_core(p, cpu, cpus, &idle_cpu);
> > if ((unsigned int)i < nr_cpumask_bits)
> > - return i;
> > + break;
> >
> > + nr -= sched_smt_weight;
> > } else {
> > - if (!--nr)
> > - return -1;
> > idle_cpu = __select_idle_cpu(cpu, p);
> > if ((unsigned int)idle_cpu < nr_cpumask_bits)
> > break;
> > + nr--;
> > }
> > +
> > + if (nr < 0)
> > + break;
> > }
> >
> > - if (has_idle_core)
> > - set_idle_cores(target, false);
> > + if ((unsigned int)idle_cpu < nr_cpumask_bits) {
> > + if (has_idle_core)
> > + set_idle_cores(target, false);
> >
>
> For example, if we have 16 cpus(8 SMT2 cores). In case core7 is idle,
> we only have scanned core0+core1(cpu0-cpu3) and if these two cores
> are not idle, but here we set has_idle_cores to false while core7 is
> idle. It seems incorrect.
>
Yep, that block needs to be revisited.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2021-08-04 10:22 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 10:22 [RFC PATCH 0/9] Modify and/or delete SIS_PROP Mel Gorman
2021-07-26 10:22 ` [PATCH 1/9] sched/fair: Track efficiency of select_idle_sibling Mel Gorman
2021-07-26 10:22 ` [PATCH 2/9] sched/fair: Track efficiency of task recent_used_cpu Mel Gorman
2021-07-26 10:22 ` [PATCH 3/9] sched/fair: Track efficiency of select_idle_core Mel Gorman
2021-07-26 10:22 ` [PATCH 4/9] sched/fair: Use prev instead of new target as recent_used_cpu Mel Gorman
2021-07-26 10:22 ` [PATCH 5/9] sched/fair: Avoid a second scan of target in select_idle_cpu Mel Gorman
2021-07-26 10:22 ` [PATCH 6/9] sched/fair: Make select_idle_cpu() proportional to cores Mel Gorman
2021-07-26 10:22 ` [PATCH 7/9] sched/fair: Enforce proportional scan limits when scanning for an idle core Mel Gorman
2021-08-02 10:52 ` Song Bao Hua (Barry Song)
2021-08-04 10:22 ` Mel Gorman [this message]
2021-07-26 10:22 ` [PATCH 8/9] sched/fair: select idle cpu from idle cpumask for task wakeup Mel Gorman
2021-08-02 10:41 ` Song Bao Hua (Barry Song)
2021-08-04 10:26 ` Mel Gorman
2021-08-05 0:23 ` Aubrey Li
2021-09-17 3:44 ` Barry Song
2021-09-17 4:15 ` Barry Song
2021-09-17 9:11 ` Aubrey Li
2021-09-17 13:35 ` Mel Gorman
2021-07-26 10:22 ` [PATCH 9/9] sched/core: Delete SIS_PROP and rely on the idle cpu mask Mel Gorman
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