lkml.org 
[lkml]   [2014]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH tip/core/timers 2/4] timers: Reduce __run_timers() latency for empty list
On Tue, Jan 14, 2014 at 09:20:46PM -0800, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>
> The __run_timers() function currently steps through the list one jiffy at
> a time in order to update the timer wheel. However, if the timer wheel
> is empty, no adjustment is needed other than updating ->timer_jiffies.
> In this case, which is likely to be common for NO_HZ_FULL kernels, the
> kernel currently incurs a large latency for no good reason. This commit
> therefore short-circuits this case.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> kernel/timer.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/kernel/timer.c b/kernel/timer.c
> index 2245b7374c3d..295837e5e011 100644
> --- a/kernel/timer.c
> +++ b/kernel/timer.c
> @@ -338,6 +338,17 @@ void set_timer_slack(struct timer_list *timer, int slack_hz)
> }
> EXPORT_SYMBOL_GPL(set_timer_slack);
>
> +static bool catchup_timer_jiffies(struct tvec_base *base)
> +{
> +#ifdef CONFIG_NO_HZ_FULL
> + if (!base->all_timers) {
> + base->timer_jiffies = jiffies;
> + return 1;
> + }
> +#endif /* #ifdef CONFIG_NO_HZ_FULL */
> + return 0;
> +}

In a function with return type "bool", please use true/false, not 1/0.

Please also document the semantic of the return value.

- Josh Triplett


\
 
 \ /
  Last update: 2014-01-15 21:41    [W:0.162 / U:0.928 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site