From: Nitesh Shetty <nj.shetty@samsung.com>
Date: Tue, 13 Feb 2018 21:18:12 +0530
Subject: [PATCH] blk: optimization for classic polling
Git-commit: 67b4110f8c8d16e588d7730db8e8b01b32c1bd8b
Patch-mainline: v4.16-rc2
References: bsc#1104967,FATE#325924
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>
Acked-by: Hannes Reinecke <hare@suse.com>
---
block/blk-mq.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index df93102e2149..357492712b0e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -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;
}
--
2.16.4