[PATCH 03/32] block: make kblockd_workqueue smarter

[Tejun Heo]

kblockd is used for unplugging and may affect IO latency and
throughput and the max number of concurrent work items are bound by
the number of block devices.  Make it HIGHPRI workqueue w/ default max
concurrency.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
---
Please feel free to take it into the subsystem tree or simply ack -
I'll route it through the wq tree.

Thanks.

 block/blk-core.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 4ce953f..909b84a 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2606,7 +2606,9 @@ int __init blk_dev_init(void)
 	BUILD_BUG_ON(__REQ_NR_BITS > 8 *
 			sizeof(((struct request *)0)->cmd_flags));
 
-	kblockd_workqueue = create_workqueue("kblockd");
+	/* used for unplugging and affects IO latency/throughput - HIGHPRI */
+	kblockd_workqueue = alloc_workqueue("kblockd",
+					    WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
 	if (!kblockd_workqueue)
 		panic("Failed to create kblockd\n");
 
-- 
1.7.1

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