| Message ID | 20170731165111.11536-3-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 2017-08-01 at 00:50 +0800, Ming Lei wrote: > When hw queue is busy, we shouldn't take requests from > scheduler queue any more, otherwise IO merge will be > difficult to do. > > This patch fixes the awful IO performance on some > SCSI devices(lpfc, qla2xxx, ...) when mq-deadline/kyber > is used by not taking requests if hw queue is busy. > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > block/blk-mq-sched.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c > index 4ab69435708c..47a25333a136 100644 > --- a/block/blk-mq-sched.c > +++ b/block/blk-mq-sched.c > @@ -94,7 +94,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) > struct request_queue *q = hctx->queue; > struct elevator_queue *e = q->elevator; > const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request; > - bool did_work = false; > + bool can_go = true; > LIST_HEAD(rq_list); > > /* RCU or SRCU read lock is needed before checking quiesced flag */ > @@ -125,7 +125,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) > */ > if (!list_empty(&rq_list)) { > blk_mq_sched_mark_restart_hctx(hctx); > - did_work = blk_mq_dispatch_rq_list(q, &rq_list); > + can_go = blk_mq_dispatch_rq_list(q, &rq_list); > } else if (!has_sched_dispatch) { > blk_mq_flush_busy_ctxs(hctx, &rq_list); > blk_mq_dispatch_rq_list(q, &rq_list); > @@ -136,7 +136,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) > * on the dispatch list, OR if we did have work but weren't able > * to make progress. > */ > - if (!did_work && has_sched_dispatch) { > + if (can_go && has_sched_dispatch) { > do { > struct request *rq; Hello Ming, Please chose a better name for the new variable, e.g. "do_sched_dispatch". Otherwise this patch looks fine to me. Hence: Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Bart.
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 4ab69435708c..47a25333a136 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -94,7 +94,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) struct request_queue *q = hctx->queue; struct elevator_queue *e = q->elevator; const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request; - bool did_work = false; + bool can_go = true; LIST_HEAD(rq_list); /* RCU or SRCU read lock is needed before checking quiesced flag */ @@ -125,7 +125,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) */ if (!list_empty(&rq_list)) { blk_mq_sched_mark_restart_hctx(hctx); - did_work = blk_mq_dispatch_rq_list(q, &rq_list); + can_go = blk_mq_dispatch_rq_list(q, &rq_list); } else if (!has_sched_dispatch) { blk_mq_flush_busy_ctxs(hctx, &rq_list); blk_mq_dispatch_rq_list(q, &rq_list); @@ -136,7 +136,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) * on the dispatch list, OR if we did have work but weren't able * to make progress. */ - if (!did_work && has_sched_dispatch) { + if (can_go && has_sched_dispatch) { do { struct request *rq;
When hw queue is busy, we shouldn't take requests from scheduler queue any more, otherwise IO merge will be difficult to do. This patch fixes the awful IO performance on some SCSI devices(lpfc, qla2xxx, ...) when mq-deadline/kyber is used by not taking requests if hw queue is busy. Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/blk-mq-sched.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)