From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>, Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@techsingularity.net>,
Thomas Gleixner <tglx@linutronix.de>,
Valentin Schneider <valentin.schneider@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Michael Neuling <mikey@neuling.org>,
Gautham R Shenoy <ego@linux.vnet.ibm.com>,
Parth Shah <parth@linux.ibm.com>
Subject: Re: [PATCH] sched/fair: Prefer idle CPU to cache affinity
Date: Mon, 1 Mar 2021 22:36:01 +0530 [thread overview]
Message-ID: <20210301170601.GJ2028034@linux.vnet.ibm.com> (raw)
In-Reply-To: <YD0L6sba9RfXX+tM@hirez.programming.kicks-ass.net>
* Peter Zijlstra <peterz@infradead.org> [2021-03-01 16:44:42]:
> On Sat, Feb 27, 2021 at 02:56:07PM -0500, Rik van Riel wrote:
> > On Fri, 2021-02-26 at 22:10 +0530, Srikar Dronamraju wrote:
>
> > > + if (sched_feat(WA_WAKER) && tnr_busy < tllc_size)
> > > + return this_cpu;
> >
> > I wonder if we need to use a slightly lower threshold on
> > very large LLCs, both to account for the fact that the
> > select_idle_cpu code may not find the single idle CPU
> > among a dozen busy ones, or because on a system with
> > hyperthreading we may often be better off picking another
> > LLC for HT contention issues?
> >
> > Maybe we could use "tnr_busy * 4 <
> > tllc_size * 3" or
> > something like that?
>
> How about:
>
> tnr_busy < tllc_size / topology_max_smt_threads()
>
> ?
Isn't topology_max_smt_threads only for x86 as of today?
Or Am I missing out?
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2021-03-01 20:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 16:40 [PATCH] sched/fair: Prefer idle CPU to cache affinity Srikar Dronamraju
2021-02-27 19:56 ` Rik van Riel
2021-03-01 13:37 ` Srikar Dronamraju
2021-03-01 15:44 ` Peter Zijlstra
2021-03-01 17:06 ` Srikar Dronamraju [this message]
2021-03-01 17:18 ` Peter Zijlstra
2021-03-02 7:39 ` Srikar Dronamraju
2021-03-02 9:10 ` Peter Zijlstra
2021-03-02 10:05 ` Srikar Dronamraju
2021-03-01 15:40 ` Peter Zijlstra
2021-03-01 17:08 ` Srikar Dronamraju
2021-03-02 9:53 ` Dietmar Eggemann
2021-03-02 10:04 ` Srikar Dronamraju
2021-03-08 13:52 ` Vincent Guittot
2021-03-10 5:52 ` Srikar Dronamraju
2021-03-10 15:37 ` Vincent Guittot
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