linux-kernel - Re: [PATCH v5 4/6] sched/fair: Provide update_sg_lb

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Message-ID: <CAKfTPtDWKkCJwimuU9DRUUyStn+ZVkUX23mNMCoqpLzXrn+jfQ@mail.gmail.com>
Date:   Fri, 17 Sep 2021 17:27:00 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Len Brown <len.brown@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Ricardo Neri <ricardo.neri@...el.com>,
        Quentin Perret <qperret@...gle.com>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        linuxppc-dev@...ts.ozlabs.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Aubrey Li <aubrey.li@...el.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH v5 4/6] sched/fair: Provide update_sg_lb_stats() with
 sched domain statistics

On Sat, 11 Sept 2021 at 03:19, Ricardo Neri
<ricardo.neri-calderon@...ux.intel.com> wrote:
>
> Before deciding to pull tasks when using asymmetric packing of tasks,
> on some architectures (e.g., x86) it is necessary to know not only the
> state of dst_cpu but also of its SMT siblings. The decision to classify
> a candidate busiest group as group_asym_packing is done in
> update_sg_lb_stats(). Give this function access to the scheduling domain
> statistics, which contains the statistics of the local group.
>
> Cc: Aubrey Li <aubrey.li@...el.com>
> Cc: Ben Segall <bsegall@...gle.com>
> Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
> Cc: Dietmar Eggemann <dietmar.eggemann@....com>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Quentin Perret <qperret@...gle.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Cc: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Tim Chen <tim.c.chen@...ux.intel.com>
> Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> Reviewed-by: Len Brown <len.brown@...el.com>
> Originally-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>

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

> ---
> Changes since v4:
>   * None
>
> Changes since v3:
>   * None
>
> Changes since v2:
>   * Introduced this patch.
>
> Changes since v1:
>   * N/A
> ---
>  kernel/sched/fair.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7a054f528bcc..c5851260b4d8 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8605,6 +8605,7 @@ group_type group_classify(unsigned int imbalance_pct,
>   * @sg_status: Holds flag indicating the status of the sched_group
>   */
>  static inline void update_sg_lb_stats(struct lb_env *env,
> +                                     struct sd_lb_stats *sds,
>                                       struct sched_group *group,
>                                       struct sg_lb_stats *sgs,
>                                       int *sg_status)
> @@ -8613,7 +8614,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
>
>         memset(sgs, 0, sizeof(*sgs));
>
> -       local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(group));
> +       local_group = group == sds->local;
>
>         for_each_cpu_and(i, sched_group_span(group), env->cpus) {
>                 struct rq *rq = cpu_rq(i);
> @@ -9176,7 +9177,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
>                                 update_group_capacity(env->sd, env->dst_cpu);
>                 }
>
> -               update_sg_lb_stats(env, sg, sgs, &sg_status);
> +               update_sg_lb_stats(env, sds, sg, sgs, &sg_status);
>
>                 if (local_group)
>                         goto next_group;
> --
> 2.17.1
>