Messages in this thread | | | Date | Wed, 15 Jan 2014 18:22:51 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/timers 2/4] timers: Reduce __run_timers() latency for empty list |
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On Wed, Jan 15, 2014 at 03:47:10PM -0500, Steven Rostedt wrote: > On Wed, 15 Jan 2014 12:32:45 -0800 > Josh Triplett <josh@joshtriplett.org> wrote: > > > On Wed, Jan 15, 2014 at 06:38:58PM +0100, Oleg Nesterov wrote: > > > forgot to mention... > > > > > > On 01/14, Paul E. McKenney wrote: > > > > > > > > +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; > > > > +} > > > > > > Do we really want ifdef? > > > > > > This check is cheap, and !CONFIG_NO_HZ_FULL case looks a bit > > > strange because we still update ->all_timers for no reason. > > > > There's an easy way to improve this: instead of using an ifdef, put > > "IS_ENABLED(CONFIG_NO_HZ_FULL) && " in the if condition. > > Why even bother with that? What's wrong with doing this check all the > time? Looks like it will save of the normal case too.
Sold! I removed the ifdef.
Thanx, Paul
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