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SubjectRe: [PATCH V2 3/3] sched: Move idle_stamp up to the core
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Hi Daniel,

On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano
<daniel.lezcano@linaro.org> wrote:
> The idle_balance modifies the idle_stamp field of the rq, making this
> information to be shared across core.c and fair.c. As we can know if the
> cpu is going to idle or not with the previous patch, let's encapsulate the
> idle_stamp information in core.c by moving it up to the caller. The
> idle_balance function returns true in case a balancing occured and the cpu
> won't be idle, false if no balance happened and the cpu is going idle.
>
> Cc: mingo@kernel.org
> Cc: alex.shi@linaro.org
> Cc: peterz@infradead.org
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> Signed-off-by: Peter Zijlstra <peterz@infradead.org>
> ---
> kernel/sched/core.c | 13 +++++++++++--
> kernel/sched/fair.c | 14 ++++++--------
> kernel/sched/sched.h | 8 +-------
> 3 files changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 16b97dd..428ee4c 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2704,8 +2704,17 @@ need_resched:
>
> pre_schedule(rq, prev);
>
> - if (unlikely(!rq->nr_running))
> - idle_balance(rq);
> +#ifdef CONFIG_SMP
> + if (unlikely(!rq->nr_running)) {
> + /*
> + * We must set idle_stamp _before_ calling idle_balance(), such
> + * that we measure the duration of idle_balance() as idle time.

Should not this be "such that we *do not* measure the duration of idle_balance()
as idle time?"

Thanks

Regards
Preeti U Murthy


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