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Commit 695588f9 authored by Viresh Kumar's avatar Viresh Kumar Committed by Tejun Heo
Browse files

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: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent bbb47bde

block/blk-core.c

+2 −1
Original line number Diff line number Diff line
@@ -3180,7 +3180,8 @@ 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");

block/blk-ioc.c

+2 −1
Original line number Diff line number Diff line
@@ -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);

block/genhd.c

+8 −4
Original line number Diff line number Diff line
@@ -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);