On 18 March 2013 16:23, Viresh Kumar viresh.kumar@linaro.org wrote:
mmc uses workqueues for running mmc_rescan(). There is no real dependency of scheduling these on the cpu which scheduled them.
On a idle system, it is observed that and idle cpu wakes up many times just to service this work. It would be better if we can schedule it on a cpu which isn't idle to save on power.
By idle cpu (from scheduler's perspective) we mean:
- Current task is idle task
- nr_running == 0
- wake_list is empty
This patch replaces the queue_delayed_work() with queue_delayed_work_on_any_cpu() siblings.
This routine would look for the closest (via scheduling domains) non-idle cpu (non-idle from schedulers perspective). If the current cpu is not idle or all cpus are idle, work will be scheduled on local cpu.
Cc: Chris Ball cjb@laptop.org Cc: linux-mmc@vger.kernel.org Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
drivers/mmc/core/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 9290bb5..adf331a 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -85,7 +85,7 @@ MODULE_PARM_DESC( static int mmc_schedule_delayed_work(struct delayed_work *work, unsigned long delay) {
return queue_delayed_work(workqueue, work, delay);
return queue_delayed_work_on_any_cpu(workqueue, work, delay);}
/*
1.7.12.rc2.18.g61b472e
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Acked-by: Ulf Hansson ulf.hansson@linaro.org