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| author | Jens Axboe <axboe@kernel.dk> | 2017-11-10 19:13:21 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-11-11 05:55:57 +0300 |
| commit | 79f720a751cad613620d0237e3b44f89f4a69181 (patch) | |
| tree | 4f530507baac038f38fa6974734f3a0595b2abb1 /include/linux/blk-mq.h | |
| parent | f0fba398fec65ff5a2e1bf8ae62718ec0450abaf (diff) | |
| download | linux-79f720a751cad613620d0237e3b44f89f4a69181.tar.xz | |
blk-mq: only run the hardware queue if IO is pending
Currently we are inconsistent in when we decide to run the queue. Using
blk_mq_run_hw_queues() we check if the hctx has pending IO before
running it, but we don't do that from the individual queue run function,
blk_mq_run_hw_queue(). This results in a lot of extra and pointless
queue runs, potentially, on flush requests and (much worse) on tag
starvation situations. This is observable just looking at top output,
with lots of kworkers active. For the !async runs, it just adds to the
CPU overhead of blk-mq.
Move the has-pending check into the run function instead of having
callers do it.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blk-mq.h')
| -rw-r--r-- | include/linux/blk-mq.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index b326208277ee..eb1e2cdffb31 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -266,7 +266,7 @@ void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async); void blk_mq_quiesce_queue(struct request_queue *q); void blk_mq_unquiesce_queue(struct request_queue *q); void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs); -void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async); +bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async); void blk_mq_run_hw_queues(struct request_queue *q, bool async); void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs); void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, |