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, 2 insertions, 1 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 9c4bb8266bc8..4464c823cff2 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -144,7 +144,8 @@ void put_io_context(struct io_context *ioc)
         if (atomic_long_dec_and_test(&ioc->refcount)) {
                 spin_lock_irqsave(&ioc->lock, flags);
                 if (!hlist_empty(&ioc->icq_list))
-                        schedule_work(&ioc->release_work);
+                        queue_work(system_power_efficient_wq,
+                                        &ioc->release_work);
                 else
                         free_ioc = true;
                 spin_unlock_irqrestore(&ioc->lock, flags);