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block: remove WQ_POWER_EFFICIENT from kblockd

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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 695588f9454b, 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>
This commit is contained in:
Matias Bjørling 2014-06-11 23:43:54 +02:00 committed by Jens Axboe
parent 54ae81cd5a
commit 28747fcd22
1 changed files with 1 additions and 2 deletions
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3
block/blk-core.c
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@ -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");