On Tue, 4 Apr 2017 07:54:14 +1000
Anton Blanchard <an...@ozlabs.org> wrote:
> From: Anton Blanchard <an...@samba.org>
>
> When in the snooze_loop() we want to take up the least amount of
> resources. On my version of gcc (6.3), we end up with an extra
> branch because it predicts snooze_timeout_en to be false, whereas it
> is almost always true.
>
> Use likely() to avoid the branch and be a little nicer to the
> other non idle threads on the core.
Patches 2 and 3 look fine. Should they be replicated to cpuidle-pseries.c
as well?
Thanks,
Nick
>
> Signed-off-by: Anton Blanchard <an...@samba.org>
> ---
> drivers/cpuidle/cpuidle-powernv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpuidle/cpuidle-powernv.c
> b/drivers/cpuidle/cpuidle-powernv.c
> index 8c991c254b95..251a60bfa8ee 100644
> --- a/drivers/cpuidle/cpuidle-powernv.c
> +++ b/drivers/cpuidle/cpuidle-powernv.c
> @@ -58,7 +58,7 @@ static int snooze_loop(struct cpuidle_device *dev,
> ppc64_runlatch_off();
> HMT_very_low();
> while (!need_resched()) {
> - if (snooze_timeout_en && get_tb() > snooze_exit_time)
> + if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time)
> break;
> }
>
