[PATCH V3 5/7] mmc: queue work on any cpu

From: Viresh Kumar
Date: Mon Mar 18 2013 - 11:24:55 EST

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@xxxxxxxxxx>
Cc: linux-mmc@xxxxxxxxxxxxxxx
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
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);


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