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Date:   Wed, 28 Dec 2022 23:29:52 +0800
From:   Chen Yu <yu.c.chen@intel.com>
To:     Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
CC:     Valentin Schneider <vschneid@redhat.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Ricardo Neri <ricardo.neri@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Ben Segall <bsegall@google.com>,
        "Daniel Bristot de Oliveira" <bristot@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Len Brown <len.brown@intel.com>, Mel Gorman <mgorman@suse.de>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        "Srinivas Pandruvada" <srinivas.pandruvada@linux.intel.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Tim Chen <tim.c.chen@linux.intel.com>, <x86@kernel.org>,
        <linux-kernel@vger.kernel.org>,
        "Tim C . Chen" <tim.c.chen@intel.com>
Subject: Re: [PATCH v2 4/7] sched/fair: Introduce sched_smt_siblings_idle()
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On 2022-12-23 at 21:28:50 -0800, 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?
>
I guess a similar one is select_idle_core(), but it also consider the CPU with
SCHED_IDLE task as idle. Is CPU with SCHED_IDLE task a candidate in your
scenario?

thanks,
Chenyu
> Thanks and BR,
> Ricardo