From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Rik van Riel <riel@surriel.com>,
Mel Gorman <mgorman@techsingularity.net>,
linux-kernel <linux-kernel@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>, Ingo Molnar <mingo@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>
Subject: Re: [PATCH v3] sched/fair: bring back select_idle_smt, but differently
Date: Wed, 7 Apr 2021 11:54:37 +0200 [thread overview]
Message-ID: <YG2BXRm60IhpumD8@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210407094217.GA2926@vingu-book>
On Wed, Apr 07, 2021 at 11:42:17AM +0200, Vincent Guittot wrote:
> I would really prefer to keep that out of select_idle_cpu which aims to merge in one
> single loop the walk through sd_llc. In the case of select_idle_smt, this is done outside
> the loop:
Fair enough.
> @@ -6317,11 +6339,21 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
> }
> }
>
> + if (static_branch_likely(&sched_smt_present)) {
> + smt = test_idle_cores(target, false);
> + if (!smt && cpus_share_cache(prev, target)) {
> + /* No idle core. Check if prev has an idle sibling. */
> + i = select_idle_smt(p, sd, prev);
> + if ((unsigned int)i < nr_cpumask_bits)
> + return i;
> + }
> + }
> +
> sd = rcu_dereference(per_cpu(sd_llc, target));
> if (!sd)
> return target;
It needs to be here, otherwise you're using @sd uninitialized.
> - i = select_idle_cpu(p, sd, target);
> + i = select_idle_cpu(p, sd, smt, target);
> if ((unsigned)i < nr_cpumask_bits)
> return i;
Let me have another poke at it.
next prev parent reply other threads:[~2021-04-07 9:55 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-21 19:03 [PATCH v2] sched/fair: bring back select_idle_smt, but differently Rik van Riel
2021-03-22 11:03 ` Mel Gorman
2021-03-22 15:07 ` Rik van Riel
2021-03-22 15:33 ` Mel Gorman
2021-03-23 2:08 ` Rik van Riel
2021-03-26 19:19 ` [PATCH v3] " Rik van Riel
2021-03-28 15:36 ` Mel Gorman
2021-04-06 15:10 ` Vincent Guittot
2021-04-06 15:26 ` Rik van Riel
2021-04-06 15:31 ` Vincent Guittot
2021-04-06 15:33 ` Vincent Guittot
2021-04-06 15:55 ` Rik van Riel
2021-04-06 16:13 ` Vincent Guittot
2021-04-07 7:17 ` Peter Zijlstra
2021-04-07 9:41 ` Mel Gorman
2021-04-07 10:15 ` Peter Zijlstra
2021-04-07 10:47 ` Mel Gorman
2021-04-07 12:10 ` Peter Zijlstra
2021-04-07 9:42 ` Vincent Guittot
2021-04-07 9:54 ` Peter Zijlstra [this message]
2021-04-07 9:57 ` Vincent Guittot
2021-04-07 10:19 ` Peter Zijlstra
2021-04-07 10:24 ` Vincent Guittot
2021-04-08 15:52 ` Rik van Riel
2021-04-09 11:24 ` [tip: sched/core] sched/fair: Bring back select_idle_smt(), " tip-bot2 for Rik van Riel
2021-04-09 16:14 ` tip-bot2 for Rik van Riel
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