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Message-ID: <75ba5884-63c0-5180-00b8-e9764306a83e@arm.com>
Date: Tue, 6 Dec 2022 19:03:37 +0100
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>
Cc: 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>,
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>,
Valentin Schneider <vschneid@...hat.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 22/11/2022 21:35, 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.
[...]
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 0e4251f83807..9517c48df50e 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1052,6 +1052,28 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
> * Scheduling class queueing methods:
> */
>
> +static inline bool is_core_idle(int cpu)
> +{
> +#ifdef CONFIG_SCHED_SMT
> + int sibling;
> +
> + for_each_cpu(sibling, cpu_smt_mask(cpu)) {
> + if (cpu == sibling)
> + continue;
> +
> + if (!idle_cpu(sibling))
> + return false;
> + }
> +#endif
> +
> + return true;
> +}
> +
> +bool sched_smt_siblings_idle(int cpu)
> +{
> + return is_core_idle(cpu);
> +}
Nitpick: Can we not just have one exported function for both use-cases:
NUMA and x86 ITMT?
[...]
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