Commit 67b4110f authored Feb 13, 2018 by Nitesh Shetty Committed by Jens Axboe Feb 13, 2018

blk: optimization for classic polling

This removes the dependency on interrupts to wake up task. Set task
state as TASK_RUNNING, if need_resched() returns true,
while polling for IO completion.
Earlier, polling task used to sleep, relying on interrupt to wake it up.
This made some IO take very long when interrupt-coalescing is enabled in
NVMe.

Reference:
http://lists.infradead.org/pipermail/linux-nvme/2018-February/015435.html



Changes since v2->v3:
	-using __set_current_state() instead of set_current_state()

Changes since v1->v2:
	-setting task state once in blk_poll, instead of multiple
callers.

Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 178e834c

block/blk-mq.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -3164,6 +3164,7 @@ static bool __blk_mq_poll(struct blk_mq_hw_ctx hctx, struct request rq)
		cpu_relax();
		}

		__set_current_state(TASK_RUNNING);
		return false;
		}