On Mon, 2018-02-05 at 23:20 +0800, Ming Lei wrote:
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index 55c0a745b427..385bbec73804 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -81,6 +81,17 @@ static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
> } else
> clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
>
> + /* need to restart all hw queues for global tags */
> + if (hctx->flags & BLK_MQ_F_GLOBAL_TAGS) {
> + struct blk_mq_hw_ctx *hctx2;
> + int i;
> +
> + queue_for_each_hw_ctx(hctx->queue, hctx2, i)
> + if (blk_mq_run_hw_queue(hctx2, true))
> + return true;
> + return false;
> + }
> +
> return blk_mq_run_hw_queue(hctx, true);
> }
This new loop looks misplaced to me. If both the BLK_MQ_F_GLOBAL_TAGS and the
BLK_MQ_F_TAG_SHARED flags are set then the outer loop in blk_mq_sched_restart()
and the inner loop in blk_mq_sched_restart_hctx() will cause more calls of
blk_mq_run_hw_queue() than necessary. Have you considered to merge the above
loop into blk_mq_sched_restart()?
Thanks,
Bart.
