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authorShuoX Liu <shuox.liu@intel.com>2012-03-29 02:19:11 +0400
committerLen Brown <len.brown@intel.com>2012-03-30 09:52:58 +0400
commit3a53396b0381ec9d5180fd8fe7a681c8ce95fd9a (patch)
tree60a0770554c64250900ccf827ff868b483ae92fe /drivers/cpuidle/governors
parent6a6ea0acc9375571a13aa8c4e105a0807e1c16a4 (diff)
downloadlinux-3a53396b0381ec9d5180fd8fe7a681c8ce95fd9a.tar.xz
cpuidle: add a sysfs entry to disable specific C state for debug purpose.
Some C states of new CPU might be not good. One reason is BIOS might configure them incorrectly. To help developers root cause it quickly, the patch adds a new sysfs entry, so developers could disable specific C state manually. In addition, C state might have much impact on performance tuning, as it takes much time to enter/exit C states, which might delay interrupt processing. With the new debug option, developers could check if a deep C state could impact performance and how much impact it could cause. Also add this option in Documentation/cpuidle/sysfs.txt. [akpm@linux-foundation.org: check kstrtol return value] Signed-off-by: ShuoX Liu <shuox.liu@intel.com> Reviewed-by: Yanmin Zhang <yanmin_zhang@intel.com> Reviewed-and-Tested-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/cpuidle/governors')
-rw-r--r--drivers/cpuidle/governors/menu.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index ad0952601ae2..5c17ca112fc2 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -280,7 +280,8 @@ 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->expected_us > 5)
+ if (data->expected_us > 5 &&
+ drv->states[CPUIDLE_DRIVER_STATE_START].disable == 0)
data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
/*
@@ -290,6 +291,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];
+ if (s->disable)
+ continue;
if (s->target_residency > data->predicted_us)
continue;
if (s->exit_latency > latency_req)