Commit fcbd7897 authored by Breno Leitao's avatar Breno Leitao Committed by Rafael J. Wysocki
Browse files

cpuidle: menu: Remove incorrect unlikely() annotation 



The unlikely() annotation on the early-return condition in menu_select()
is incorrect on systems with only one idle state (e.g., ARM64 servers
with a single ACPI LPI state). Branch profiling shows 100% misprediction
on such systems since drv->state_count <= 1 is always true.

On platforms where only state0 is available, this path is the common
case, not an unlikely edge case. Remove the misleading annotation to
let the branch predictor learn the actual behavior.

Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260105-annotated_idle-v1-1-10ddf0771b58@debian.org


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent be6a1508

drivers/cpuidle/governors/menu.c

+1 −1
Original line number Diff line number Diff line
@@ -271,7 +271,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, 
		data->bucket = BUCKETS - 1;

	}



	if (unlikely(drv->state_count <= 1 || latency_req == 0) ||

	if (drv->state_count <= 1 || latency_req == 0 ||

	    ((data->next_timer_ns < drv->states[1].target_residency_ns ||

	      latency_req < drv->states[1].exit_latency_ns) &&

	     !dev->states_usage[0].disable)) {