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(-)
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);