linux-kernel - Re: [RFCv7 PATCH 04/10] sched/fair: add triggers for OPP change requests

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Date:	Tue, 1 Mar 2016 14:51:12 +0800
From:	Ricky Liang <jcliang@...omium.org>
To:	Steve Muckle <steve.muckle@...aro.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	open list <linux-kernel@...r.kernel.org>,
	linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Juri Lelli <Juri.Lelli@....com>,
	Patrick Bellasi <patrick.bellasi@....com>,
	Michael Turquette <mturquette@...libre.com>
Subject: Re: [RFCv7 PATCH 04/10] sched/fair: add triggers for OPP change requests

Hi Steve,

On Tue, Feb 23, 2016 at 9:22 AM, Steve Muckle <steve.muckle@...aro.org> wrote:
> From: Juri Lelli <juri.lelli@....com>
>
> Each time a task is {en,de}queued we might need to adapt the current
> frequency to the new usage. Add triggers on {en,de}queue_task_fair() for
> this purpose.  Only trigger a freq request if we are effectively waking up
> or going to sleep.  Filter out load balancing related calls to reduce the
> number of triggers.
>
> [smuckle@...aro.org: resolve merge conflicts, define task_new,
>  use renamed static key sched_freq]
>
> cc: Ingo Molnar <mingo@...hat.com>
> cc: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Juri Lelli <juri.lelli@....com>
> Signed-off-by: Steve Muckle <smuckle@...aro.org>
> ---
>  kernel/sched/fair.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 47 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 3437e01..f1f00a4 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4283,6 +4283,21 @@ static inline void hrtick_update(struct rq *rq)
>  }
>  #endif
>
> +static unsigned long capacity_orig_of(int cpu);
> +static int cpu_util(int cpu);
> +
> +static void update_capacity_of(int cpu)
> +{
> +       unsigned long req_cap;
> +
> +       if (!sched_freq())
> +               return;
> +
> +       /* Convert scale-invariant capacity to cpu. */
> +       req_cap = cpu_util(cpu) * SCHED_CAPACITY_SCALE / capacity_orig_of(cpu);
> +       set_cfs_cpu_capacity(cpu, true, req_cap);
> +}
> +

The change hunks of this patch should probably all depend on
CONFIG_SMP as capacity_orig_of() and cpu_util() are only available
when CONFIG_SMP is enabled.

[snip...]

Thanks,
Ricky