From: Stephen Boyd <sboyd@codeaurora.org>
To: Joonwoo Park <joonwoop@codeaurora.org>, tglx@linutronix.de
Cc: skannan@codeaurora.org, linux-kernel@vger.kernel.org,
John Stultz <john.stultz@linaro.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH 1/2] timer: avoid unnecessary waking up of nohz CPU
Date: Tue, 28 Apr 2015 14:59:04 -0700 [thread overview]
Message-ID: <554002A8.4070008@codeaurora.org> (raw)
In-Reply-To: <1430187709-21087-1-git-send-email-joonwoop@codeaurora.org>
On 04/27/15 19:21, Joonwoo Park wrote:
> At present, internal_add_timer() examines flags with 'base' which doesn't
> contain flags. Examine with 'timer->base' to avoid unnecessary waking up
> of nohz CPU when timer base has TIMER_DEFERRABLE.
>
> CC: Thomas Gleixner <tglx@linutronix.de>
> CC: John Stultz <john.stultz@linaro.org>
> Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
> ---
> kernel/time/timer.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/time/timer.c b/kernel/time/timer.c
> index 2ece3aa..e5d5733c 100644
> --- a/kernel/time/timer.c
> +++ b/kernel/time/timer.c
> @@ -434,7 +434,7 @@ static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
> * require special care against races with idle_cpu(), lets deal
> * with that later.
> */
> - if (!tbase_get_deferrable(base) || tick_nohz_full_cpu(base->cpu))
> + if (!tbase_get_deferrable(timer->base) || tick_nohz_full_cpu(base->cpu))
> wake_up_nohz_cpu(base->cpu);
> }
>
This looks like a fix for commit 9f6d9baaa8ca (timer: Kick dynticks
targets on mod_timer*() calls, 2014-06-22) which changed the code to use
base instead of timer->base when it moved this condition from
add_timer_on() into internal_add_timer(). Is that right?
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2015-04-28 21:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-28 2:21 [PATCH 1/2] timer: avoid unnecessary waking up of nohz CPU Joonwoo Park
2015-04-28 21:59 ` Stephen Boyd [this message]
2015-04-29 2:41 ` Viresh Kumar
2015-05-05 8:42 ` [tip:timers/core] timer: Use timer->base for flag checks tip-bot for Joonwoo Park
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