block: queue work on power efficient wq

Block layer uses workqueues for multiple purposes. 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 the
scheduler believes to be the most appropriate one.

This patch replaces normal workqueues with power efficient versions.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/block/genhd.c b/block/genhd.c
index 20625eed5511..e9094b375c05 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1489,9 +1489,11 @@ static void __disk_unblock_events(struct gendisk *disk, bool check_now)
         intv = disk_events_poll_jiffies(disk);
         set_timer_slack(&ev->dwork.timer, intv / 4);
         if (check_now)
-                queue_delayed_work(system_freezable_wq, &ev->dwork, 0);
+                queue_delayed_work(system_freezable_power_efficient_wq,
+                                &ev->dwork, 0);
         else if (intv)
-                queue_delayed_work(system_freezable_wq, &ev->dwork, intv);
+                queue_delayed_work(system_freezable_power_efficient_wq,
+                                &ev->dwork, intv);
 out_unlock:
         spin_unlock_irqrestore(&ev->lock, flags);
 }
@@ -1534,7 +1536,8 @@ void disk_flush_events(struct gendisk *disk, unsigned int mask)
         spin_lock_irq(&ev->lock);
         ev->clearing |= mask;
         if (!ev->block)
-                mod_delayed_work(system_freezable_wq, &ev->dwork, 0);
+                mod_delayed_work(system_freezable_power_efficient_wq,
+                                &ev->dwork, 0);
         spin_unlock_irq(&ev->lock);
 }
 
@@ -1627,7 +1630,8 @@ static void disk_check_events(struct disk_events *ev,
 
         intv = disk_events_poll_jiffies(disk);
         if (!ev->block && intv)
-                queue_delayed_work(system_freezable_wq, &ev->dwork, intv);
+                queue_delayed_work(system_freezable_power_efficient_wq,
+                                &ev->dwork, intv);
 
         spin_unlock_irq(&ev->lock);