Re: [PATCH v5 3/6] sched/fair: Optimize checking for group_asym_packing

From: Vincent Guittot <vincent.guittot@linaro.org>
To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Len Brown <len.brown@intel.com>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Aubrey Li <aubrey.li@linux.intel.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Ricardo Neri <ricardo.neri@intel.com>,
	Quentin Perret <qperret@google.com>,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>,
	linuxppc-dev@lists.ozlabs.org,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Aubrey Li <aubrey.li@intel.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH v5 3/6] sched/fair: Optimize checking for group_asym_packing
Date: Fri, 17 Sep 2021 17:26:26 +0200	[thread overview]
Message-ID: <CAKfTPtCHFgaWWdxSuRKPrp4cSLA+pTzXAmsGn9N3LrFn0x4B1w@mail.gmail.com> (raw)
In-Reply-To: <20210911011819.12184-4-ricardo.neri-calderon@linux.intel.com>

On Sat, 11 Sept 2021 at 03:19, Ricardo Neri
<ricardo.neri-calderon@linux.intel.com> wrote:
>
> sched_asmy_prefer() always returns false when called on the local group. By
> checking local_group, we can avoid additional checks and invoking
> sched_asmy_prefer() when it is not needed. No functional changes are
> introduced.
>
> Cc: Aubrey Li <aubrey.li@intel.com>
> Cc: Ben Segall <bsegall@google.com>
> Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Quentin Perret <qperret@google.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Tim Chen <tim.c.chen@linux.intel.com>
> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> Reviewed-by: Len Brown <len.brown@intel.com>
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>

Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>

> ---
> Changes since v4:
>   * None
>
> Changes since v3:
>   * Further rewording of the commit message. (Len)
>
> Changes since v2:
>   * Reworded the commit message for clarity. (Peter Z)
>
> Changes since v1:
>   * None
> ---
>  kernel/sched/fair.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index ff69f245b939..7a054f528bcc 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8657,7 +8657,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
>         }
>
>         /* Check if dst CPU is idle and preferred to this group */
> -       if (env->sd->flags & SD_ASYM_PACKING &&
> +       if (!local_group && env->sd->flags & SD_ASYM_PACKING &&
>             env->idle != CPU_NOT_IDLE &&
>             sgs->sum_h_nr_running &&
>             sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu)) {
> --
> 2.17.1
>