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SubjectRe: [PATCH] sched: update blocked load of idle cpus
Hi Vincent,

On Wed, Jun 24, 2015 at 09:11:12AM +0200, Vincent Guittot wrote:
> The load and the util of idle cpus must be updated periodically in order to
> decay the blocked part.
>
> If CONFIG_FAIR_GROUP_SCHED is not set, the load and util of idle cpus
> are not decayed and stay at the values set before becoming idle.
>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> Hi Yuyang,
>
> While testing your patchset without CONFIG_FAIR_GROUP_SCHED, i have noticed
> that the load of idle cpus stays sometimes to an high value whereas they were
> not used for a while because we are not decaying the blocked load.
> Futhermore, the peridodic load balance was not pulling tasks onto some idle
> cpus because their load stayed high.
>
> This patchset fixes the issue.

Thanks. We should privide an update_blocked_averages() for the
CONFIG_FAIR_GROUP_SCHED=n case. Great.

>
> Regards,
> Vincent
>
> kernel/sched/fair.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index c5f18d9..665cc4b 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5864,6 +5864,17 @@ static unsigned long task_h_load(struct task_struct *p)
> #else
> static inline void update_blocked_averages(int cpu)
> {
> + struct rq *rq = cpu_rq(cpu);
> + struct cfs_rq *cfs_rq = &rq->cfs;
> + unsigned long flags;
> +
> + raw_spin_lock_irqsave(&rq->lock, flags);
> + update_rq_clock(rq);
> +
> + update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq))
> +
> + raw_spin_unlock_irqrestore(&rq->lock, flags);
> +
> }
>
> static unsigned long task_h_load(struct task_struct *p)

Reviewed-by: Yuyang Du <yuyang.du@intel.com>

> --
> 1.9.1


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