On Thu, 27 Mar 2014, Viresh Kumar wrote:
> If active_bases already has entry for a particular clock type, then we don't
> need to rewrite it while queuing a hrtimer.
>
> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
> ---
> Initially I thought of doing this but then thought better remove active_bases
> completely and so didn't sent this one. Now it might find some place for
> itself
> :).
>
> kernel/hrtimer.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
> index da351ad..acfef5f 100644
> --- a/kernel/hrtimer.c
> +++ b/kernel/hrtimer.c
> @@ -864,8 +864,9 @@ static int enqueue_hrtimer(struct hrtimer *timer,
> {
> debug_activate(timer);
>
> + if (!timerqueue_getnext(&base->active))
> + base->cpu_base->active_bases |= 1 << base->index;
> timerqueue_add(&base->active, &timer->node);
> - base->cpu_base->active_bases |= 1 << base->index;
The conditional is more expensive than actually doing the OR operation
at least on x86 as it results in a branch.
Thanks,
tglx
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