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: Tue, 2 Mar 2021 15:35:27 +0530 [thread overview]
Message-ID: <20210302100527.GN2028034@linux.vnet.ibm.com> (raw)
In-Reply-To: <YD4BCDlxvn7ub+9U@hirez.programming.kicks-ass.net>
* Peter Zijlstra <peterz@infradead.org> [2021-03-02 10:10:32]:
> On Tue, Mar 02, 2021 at 01:09:46PM +0530, Srikar Dronamraju wrote:
> > > Oh, could be, I didn't grep :/ We could have core code keep track of the
> > > smt count I suppose.
> >
> > Could we use cpumask_weight(cpu_smt_mask(this_cpu)) instead?
>
> cpumask_weight() is potentially super expensive. With CPUMASK_OFFSTACK
> you get at least one more cache miss and then the bitmap might be really
> long.
>
> Best to compute the results once and use it later.
Oh okay .. Noted.
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2021-03-02 10:29 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
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 [this message]
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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