diff options
| author | ShuoX Liu <shuox.liu@intel.com> | 2012-03-28 15:19:11 -0700 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2012-03-30 01:52:58 -0400 |
| commit | 3a53396b0381ec9d5180fd8fe7a681c8ce95fd9a (patch) | |
| tree | 60a0770554c64250900ccf827ff868b483ae92fe /drivers/cpuidle/governors/menu.c | |
| parent | 6a6ea0acc9375571a13aa8c4e105a0807e1c16a4 (diff) | |
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/menu.c')
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 5 |
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) |