linux-kernel - Re: [Patch v10 6/9] sched/fair: Enable periodic update of average thermal pressure

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Message-ID: <CAHLCerNWYHSE=0m_AqH2UY6gKvK7EV64JaZxnLC_TufNrO7ZBg@mail.gmail.com>
Date:   Thu, 27 Feb 2020 14:33:01 +0530
From:   Amit Kucheria <amit.kucheria@...durent.com>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>, ionela.voinescu@....com,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Zhang Rui <rui.zhang@...el.com>, qperret@...gle.com,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        LKML <linux-kernel@...r.kernel.org>,
        Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Javi Merino <javi.merino@...nel.org>
Subject: Re: [Patch v10 6/9] sched/fair: Enable periodic update of average
 thermal pressure

On Sat, Feb 22, 2020 at 6:22 AM Thara Gopinath
<thara.gopinath@...aro.org> wrote:
>
> Introduce support in scheduler periodic tick and other CFS bookkeeping
> apis to trigger the process of computing average thermal pressure for a
> cpu. Also consider avg_thermal.load_avg in others_have_blocked which
> allows for decay of pelt signals.
>
> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> ---
> v8->v9:
>         - Moved periodic triggering of thermal pressure averaging from CFS
>           tick function to generic scheduler core tick function as per
>           Peter's review comments.
>
>  kernel/sched/core.c | 3 +++
>  kernel/sched/fair.c | 7 +++++++
>  2 files changed, 10 insertions(+)

Hi Thara,

This patch has a fuzz while applying to v5.6-rc2. Just FYI.

Regards,
Amit


>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index e94819d573be..160b5e9e8945 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3588,6 +3588,7 @@ void scheduler_tick(void)
>         struct rq *rq = cpu_rq(cpu);
>         struct task_struct *curr = rq->curr;
>         struct rq_flags rf;
> +       unsigned long thermal_pressure;
>
>         arch_scale_freq_tick();
>         sched_clock_tick();
> @@ -3595,6 +3596,8 @@ void scheduler_tick(void)
>         rq_lock(rq, &rf);
>
>         update_rq_clock(rq);
> +       thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
> +       update_thermal_load_avg(rq_clock_task(rq), rq, thermal_pressure);
>         curr->sched_class->task_tick(rq, curr, 0);
>         calc_global_load_tick(rq);
>         psi_task_tick(rq);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index f38ff5a335d3..00b21a5b71f0 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7536,6 +7536,9 @@ static inline bool others_have_blocked(struct rq *rq)
>         if (READ_ONCE(rq->avg_dl.util_avg))
>                 return true;
>
> +       if (thermal_load_avg(rq))
> +               return true;
> +
>  #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
>         if (READ_ONCE(rq->avg_irq.util_avg))
>                 return true;
> @@ -7561,6 +7564,7 @@ static bool __update_blocked_others(struct rq *rq, bool *done)
>  {
>         const struct sched_class *curr_class;
>         u64 now = rq_clock_pelt(rq);
> +       unsigned long thermal_pressure;
>         bool decayed;
>
>         /*
> @@ -7569,8 +7573,11 @@ static bool __update_blocked_others(struct rq *rq, bool *done)
>          */
>         curr_class = rq->curr->sched_class;
>
> +       thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
> +
>         decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
>                   update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
> +                 update_thermal_load_avg(rq_clock_task(rq), rq, thermal_pressure) |
>                   update_irq_load_avg(rq, 0);
>
>         if (others_have_blocked(rq))
> --
> 2.20.1
>