linux-kernel - Re: [PATCH v2 4/7] sched/fair: Introduce sched_smt_siblings

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Message-ID: <xhsmhy1qaci18.mognet@vschneid.remote.csb>
Date:   Tue, 10 Jan 2023 19:21:23 +0000
From:   Valentin Schneider <vschneid@...hat.com>
To:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Ricardo Neri <ricardo.neri@...el.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Len Brown <len.brown@...el.com>, Mel Gorman <mgorman@...e.de>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, "Tim C . Chen" <tim.c.chen@...el.com>
Subject: Re: [PATCH v2 4/7] sched/fair: Introduce sched_smt_siblings_idle()

On 23/12/22 21:28, Ricardo Neri wrote:
> On Thu, Dec 22, 2022 at 04:56:22PM +0000, Valentin Schneider wrote:
>> On 22/11/22 12:35, Ricardo Neri wrote:
>> > Architectures that implement arch_asym_cpu_priority() may need to know the
>> > idle state of the SMT siblings of a CPU. The scheduler has this information
>> > and functionality. Expose it.
>> >
>> > Move the existing functionality outside of the NUMA code.
>> >
>> 
>> test_idle_cores() does something similar without an iteration, did you
>> consider using that instead?
>
> IIUC, test_idle_cores() returns true if there is at least one idle core in
> the package. In my case, I need to know the idle state of only the SMT
> siblings of a specific CPU. Am I missing something?
>

No, you're right, clearly I needed that end of the year break - sorry for
the noise.

> Thanks and BR,
> Ricardo