On 02/15/2017 09:45 AM, Omar Sandoval wrote: > From: Omar Sandoval <osandov@xxxxxx> > > In blk_mq_sched_dispatch_requests(), we call blk_mq_sched_mark_restart() > after we dispatch requests left over on our hardware queue dispatch > list. This is so we'll go back and dispatch requests from the scheduler. > In this case, it's only necessary to restart the hardware queue that we > are running; there's no reason to run other hardware queues just because > we are using shared tags. > > So, split out blk_mq_sched_mark_restart() into two operations, one for > just the hardware queue and one for the whole request queue. The core > code uses both, and I/O schedulers may also want to use them. > > This also requires adjusting blk_mq_sched_restart_queues() to always > check the queue restart flag, not just when using shared tags. Looks good to me - just one comment: > @@ -936,7 +936,10 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list) > * in case the needed IO completed right before we > * marked the queue as needing a restart. > */ > - blk_mq_sched_mark_restart(hctx); > + if (hctx->flags & BLK_MQ_F_TAG_SHARED) > + blk_mq_sched_mark_restart_queue(hctx); > + else > + blk_mq_sched_mark_restart_hctx(hctx); > if (!blk_mq_get_driver_tag(rq, &hctx, false)) > break; > } Since we now pushed the SHARED tag into the caller, I think this warrants a comment as to why the two cases are different (getting a driver tag can fail with 0 pending IOs for SHARED). Just update the existing comment. -- Jens Axboe
