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 <ax...@kernel.dk>
Signed-off-by: Viresh Kumar <viresh.ku...@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);
--
1.7.12.rc2.18.g61b472e
--
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