Commit 28747fcd authored Jun 11, 2014 by Matias Bjørling Committed by Jens Axboe Jun 11, 2014

block: remove WQ_POWER_EFFICIENT from kblockd



blk-mq issues async requests through kblockd. To issue a work request on
a specific CPU, kblockd_schedule_delayed_work_on is used. However, the
specific CPU choice may not be honored, if the power_efficient option
for workqueues is set. blk-mq requires that we have strict per-cpu
scheduling, so it wont work properly if kblockd is marked
POWER_EFFICIENT and power_efficient is set.

Remove the kblockd WQ_POWER_EFFICIENT flag to prevent this behavior.
This essentially reverts part of commit 695588f9, which added
the WQ_POWER_EFFICIENT marker to kblockd.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 54ae81cd

block/blk-core.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -3311,8 +3311,7 @@ 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 \|
		WQ_POWER_EFFICIENT, 0);
		WQ_MEM_RECLAIM \| WQ_HIGHPRI, 0);
		if (!kblockd_workqueue)
		panic("Failed to create kblockd\n");

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