[V5,4/5] block: queue work on power efficient wq

Message ID 2e89f7f3943438f8b1e58f2034242a5b53e31b43.1366803121.git.viresh.kumar@linaro.org
State Accepted
Headers show

Commit Message

Viresh Kumar April 24, 2013, 11:42 a.m.
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>
---
 block/blk-core.c |  3 ++-
 block/blk-ioc.c  |  3 ++-
 block/genhd.c    | 12 ++++++++----
 3 files changed, 12 insertions(+), 6 deletions(-)

Comments

Tejun Heo May 14, 2013, 5:57 p.m. | #1
On Wed, Apr 24, 2013 at 05:12:56PM +0530, Viresh Kumar wrote:
> 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>

Jens, applied this to wq/for-3.11.  Please holler if you wanna route
this differently.

Thanks.

Patch

diff --git a/block/blk-core.c b/block/blk-core.c
index 94aa4e7..3eb9870 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3187,7 +3187,8 @@  int __init blk_dev_init(void)
 
 	/* used for unplugging and affects IO latency/throughput - HIGHPRI */
 	kblockd_workqueue = alloc_workqueue("kblockd",
-					    WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
+					    WQ_MEM_RECLAIM | WQ_HIGHPRI |
+					    WQ_POWER_EFFICIENT, 0);
 	if (!kblockd_workqueue)
 		panic("Failed to create kblockd\n");
 
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 9c4bb82..4464c82 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);
diff --git a/block/genhd.c b/block/genhd.c
index 5a9f893..2e1cfe3 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);