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SubjectRe: [PATCH] nohz: Remove ts->inidle checks before restarting the tick
On Tue, Dec 06, 2011 at 03:30:43PM +0100, Frederic Weisbecker wrote:
> ts->inidle is set by tick_nohz_stop_sched_tick(1) and unset
> by tick_nohz_restart_sched_tick(). These two calls are assumed
> to be always paired. This means that by the time we call
> tick_nohz_restart_sched_tick(), ts->inidle is supposed to
> be always set to 1.
>
> Remove the checks for ts->inidle in tick_nohz_restart_sched_tick().
> This simplifies a bit the code and improves its debuggability
> (ie: ensure the call is paired with a tick_nohz_stop_sched_tick() call).
>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

Reviewed-by: Yong Zhang <yong.zhang0@gmail.com>

Thanks,
Yong


> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Ingo Molnar <mingo@elte.hu>
> ---
> kernel/time/tick-sched.c | 12 +++++++-----
> 1 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 4042064..0f7c5e5 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -529,20 +529,22 @@ void tick_nohz_restart_sched_tick(void)
> ktime_t now;
>
> local_irq_disable();
> - if (ts->idle_active || (ts->inidle && ts->tick_stopped))
> +
> + WARN_ON_ONCE(!ts->inidle);
> +
> + ts->inidle = 0;
> +
> + if (ts->idle_active || ts->tick_stopped)
> now = ktime_get();
>
> if (ts->idle_active)
> tick_nohz_stop_idle(cpu, now);
>
> - if (!ts->inidle || !ts->tick_stopped) {
> - ts->inidle = 0;
> + if (!ts->tick_stopped) {
> local_irq_enable();
> return;
> }
>
> - ts->inidle = 0;
> -
> rcu_exit_nohz();
>
> /* Update jiffies first */
> --
> 1.7.5.4
>
> --
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