From 7884084f3bcc98adfbd8b90a2bd6bcf10c4df2cd Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Tue, 3 Nov 2015 17:34:17 -0500 Subject: cpuidle,x86: increase forced cut-off for polling to 20us The cpuidle menu governor has a forced cut-off for polling at 5us, in order to deal with firmware that gives the OS bad information on cpuidle states, leading to the system spending way too much time in polling. However, at least one x86 CPU family (Atom) has chips that have a 20us break-even point for C1. Forcing the polling cut-off to less than that wastes performance and power. Increase the polling cut-off to 20us. Systems with a lower C1 latency will be found in the states table by the menu governor, which will pick those states as appropriate. Signed-off-by: Rik van Riel Acked-by: Arjan van de Ven Signed-off-by: Rafael J. Wysocki diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 22e4463..ecc242a 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -330,7 +330,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) * We want to default to C1 (hlt), not to busy polling * unless the timer is happening really really soon. */ - if (data->next_timer_us > 5 && + if (data->next_timer_us > 20 && !drv->states[CPUIDLE_DRIVER_STATE_START].disabled && dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable == 0) data->last_state_idx = CPUIDLE_DRIVER_STATE_START; -- cgit v0.10.2