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authorRik van Riel <riel@redhat.com>2015-11-03 17:34:17 -0500
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-11-17 02:24:24 +0100
commit7884084f3bcc98adfbd8b90a2bd6bcf10c4df2cd (patch)
tree573e7538a7cf45fdbee7f9a33626faf9c5502bd4 /drivers/cpuidle
parent8005c49d9aea74d382f474ce11afbbc7d7130bec (diff)
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 <riel@redhat.com> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/governors/menu.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 22e4463d1787..ecc242a586c9 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;