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    SubjectRe: [PATCH v5 07/10] sched/irq: add irq utilization tracking
    Hi Dietmar,

    Sorry for the late answer

    On 31 May 2018 at 18:54, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
    > On 05/30/2018 08:45 PM, Vincent Guittot wrote:
    >> Hi Dietmar,
    >>
    >> On 30 May 2018 at 17:55, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
    >>> On 05/25/2018 03:12 PM, Vincent Guittot wrote:
    >
    > [...]
    >
    >>>> + */
    >>>> + ret = ___update_load_sum(rq->clock - running, rq->cpu,
    >>>> &rq->avg_irq,
    >>>> + 0,
    >>>> + 0,
    >>>> + 0);
    >>>> + ret += ___update_load_sum(rq->clock, rq->cpu, &rq->avg_irq,
    >>>> + 1,
    >>>> + 1,
    >>>> + 1);
    >
    > Can you not change the function parameter list to the usual
    > (u64 now, struct rq *rq, int running)?
    >
    > Something like this (only compile and boot tested):

    To be honest, I prefer to keep the specific sequence above in a
    dedicated function instead of adding it in core code.
    Furthermore, we end up calling call twice ___update_load_avg instead
    of only once. This will set an intermediate and incorrect value in
    util_avg and this value can be read in the meantime

    Vincent

    >
    > -- >8 --
    >
    > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    > index 9894bc7af37e..26ffd585cab8 100644
    > --- a/kernel/sched/core.c
    > +++ b/kernel/sched/core.c
    > @@ -177,8 +177,22 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
    > rq->clock_task += delta;
    >
    > #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
    > - if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
    > - update_irq_load_avg(rq, irq_delta + steal);
    > + if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) {
    > + /*
    > + * We know the time that has been used by interrupt since last
    > + * update but we don't when. Let be pessimistic and assume that
    > + * interrupt has happened just before the update. This is not
    > + * so far from reality because interrupt will most probably
    > + * wake up task and trig an update of rq clock during which the
    > + * metric si updated.
    > + * We start to decay with normal context time and then we add
    > + * the interrupt context time.
    > + * We can safely remove running from rq->clock because
    > + * rq->clock += delta with delta >= running
    > + */
    > + update_irq_load_avg(rq_clock(rq) - (irq_delta + steal), rq, 0);
    > + update_irq_load_avg(rq_clock(rq), rq, 1);
    > + }
    > #endif
    > }
    >
    > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
    > index 1bb3379c4b71..a245f853c271 100644
    > --- a/kernel/sched/fair.c
    > +++ b/kernel/sched/fair.c
    > @@ -7363,7 +7363,7 @@ static void update_blocked_averages(int cpu)
    > }
    > update_rt_rq_load_avg(rq_clock_task(rq), rq, 0);
    > update_dl_rq_load_avg(rq_clock_task(rq), rq, 0);
    > - update_irq_load_avg(rq, 0);
    > + update_irq_load_avg(rq_clock(rq), rq, 0);
    > /* Don't need periodic decay once load/util_avg are null */
    > if (others_rqs_have_blocked(rq))
    > done = false;
    > @@ -7434,7 +7434,7 @@ static inline void update_blocked_averages(int cpu)
    > update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq);
    > update_rt_rq_load_avg(rq_clock_task(rq), rq, 0);
    > update_dl_rq_load_avg(rq_clock_task(rq), rq, 0);
    > - update_irq_load_avg(rq, 0);
    > + update_irq_load_avg(rq_clock(rq), rq, 0);
    > #ifdef CONFIG_NO_HZ_COMMON
    > rq->last_blocked_load_update_tick = jiffies;
    > if (!cfs_rq_has_blocked(cfs_rq) && !others_rqs_have_blocked(rq))
    > diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
    > index d2e4f2186b13..ae01bb18e28c 100644
    > --- a/kernel/sched/pelt.c
    > +++ b/kernel/sched/pelt.c
    > @@ -365,31 +365,15 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
    > *
    > */
    >
    > -int update_irq_load_avg(struct rq *rq, u64 running)
    > +int update_irq_load_avg(u64 now, struct rq *rq, int running)
    > {
    > - int ret = 0;
    > - /*
    > - * We know the time that has been used by interrupt since last update
    > - * but we don't when. Let be pessimistic and assume that interrupt has
    > - * happened just before the update. This is not so far from reality
    > - * because interrupt will most probably wake up task and trig an update
    > - * of rq clock during which the metric si updated.
    > - * We start to decay with normal context time and then we add the
    > - * interrupt context time.
    > - * We can safely remove running from rq->clock because
    > - * rq->clock += delta with delta >= running
    > - */
    > - ret = ___update_load_sum(rq->clock - running, rq->cpu, &rq->avg_irq,
    > - 0,
    > - 0,
    > - 0);
    > - ret += ___update_load_sum(rq->clock, rq->cpu, &rq->avg_irq,
    > - 1,
    > - 1,
    > - 1);
    > -
    > - if (ret)
    > + if (___update_load_sum(now, rq->cpu, &rq->avg_irq,
    > + running,
    > + running,
    > + running)) {
    > ___update_load_avg(&rq->avg_irq, 1, 1);
    > + return 1;
    > + }
    >
    > - return ret;
    > + return 0;
    > }
    > diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h
    > index 0ce9a5a5877a..ebc57301a9a8 100644
    > --- a/kernel/sched/pelt.h
    > +++ b/kernel/sched/pelt.h
    > @@ -5,7 +5,7 @@ int __update_load_avg_se(u64 now, int cpu, struct cfs_rq *cfs_rq, struct sched_e
    > int __update_load_avg_cfs_rq(u64 now, int cpu, struct cfs_rq *cfs_rq);
    > int update_rt_rq_load_avg(u64 now, struct rq *rq, int running);
    > int update_dl_rq_load_avg(u64 now, struct rq *rq, int running);
    > -int update_irq_load_avg(struct rq *rq, u64 running);
    > +int update_irq_load_avg(u64 now, struct rq *rq, int running);
    >
    > /*
    > * When a task is dequeued, its estimated utilization should not be update if
    >
    >

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