Messages in this thread | | | Date | Wed, 15 Jan 2014 12:33:55 -0800 | From | Josh Triplett <> | Subject | Re: [PATCH tip/core/timers 2/4] timers: Reduce __run_timers() latency for empty list |
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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
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