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cpuidle: powernv: Avoid a branch in the core snooze_loop() loop 

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.

Signed-off-by: Anton Blanchard <anton@samba.org>
Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Anton Blanchard 2017-04-04 07:54:14 +10:00 committed by Rafael J. Wysocki
parent 26eb48a9fa
commit 0baa91cb73
1 changed files with 1 additions and 1 deletions
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2
drivers/cpuidle/cpuidle-powernv.c
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@ -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;
}