From 8b007ebec9a5d120d25c00d9b771aadf45ac5177 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 2 Oct 2018 23:46:28 +0200 Subject: cpuidle: menu: Avoid computations for very close timers If the next timer event (not including the tick) is closer than the target residency of the second state or the PM QoS latency constraint is below its exit latency, state[0] will be used regardless of any other factors, so skip the computations in menu_select() then and return 0 straight away from it. Still, do that after the bucket has been determined to avoid updating the correction factor for a stale bucket. Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel) --- drivers/cpuidle/governors/menu.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'drivers/cpuidle') diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 968379d4f207..667606c6e284 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -309,6 +309,18 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, get_iowait_load(&nr_iowaiters, &cpu_load); data->bucket = which_bucket(data->next_timer_us, nr_iowaiters); + if (unlikely(drv->state_count <= 1) || + ((data->next_timer_us < drv->states[1].target_residency || + latency_req < drv->states[1].exit_latency) && + !drv->states[0].disabled && !dev->states_usage[0].disable)) { + /* + * In this case state[0] will be used no matter what, so return + * it right away and keep the tick running. + */ + *stop_tick = false; + return 0; + } + /* * Force the result of multiplication to be 64 bits even if both * operands are 32 bits. -- cgit