| Message ID | 20170711182103.11461-4-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 2017-07-12 at 02:21 +0800, Ming Lei wrote: > Before mq IO scheduler is in, we always send the request to > dispatch list if .queue_rq() return busy. After mq IO scheduler > is introduced, we only do this way when scheduler is used in > case of direct issue. Actually we can do that when scheduler > isn't used too. > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > block/blk-mq.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 041f7b7fa0d6..6e0fc80aa151 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -1463,6 +1463,16 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq) > return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true); > } > > +static void blk_mq_direct_dispatch(struct blk_mq_hw_ctx *hctx, > + struct request *rq) > +{ > + spin_lock(&hctx->lock); > + list_add(&rq->queuelist, &hctx->dispatch); > + spin_unlock(&hctx->lock); > + > + blk_mq_run_hw_queue(hctx, false); > +} > + > static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, > struct request *rq, > blk_qc_t *cookie, bool may_sleep) > @@ -1499,15 +1509,17 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, > switch (ret) { > case BLK_STS_OK: > *cookie = new_cookie; > - return; > + break; > case BLK_STS_RESOURCE: > __blk_mq_requeue_request(rq); > - goto insert; > + blk_mq_direct_dispatch(hctx, rq); > + break; > default: > *cookie = BLK_QC_T_NONE; > blk_mq_end_request(rq, ret); > - return; > + break; > } > + return; > > insert: > blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep); Hello Ming, This patch changes the behavior of blk_mq_try_issue_directly() if a scheduler has been configured and .queue_rq() returns BLK_STS_RESOURCE, namely by skipping the e->type->ops.mq.insert_requests() call. Sorry but I don't think this is what we want. Bart.
On Tue, Jul 11, 2017 at 08:18:51PM +0000, Bart Van Assche wrote: > On Wed, 2017-07-12 at 02:21 +0800, Ming Lei wrote: > > Before mq IO scheduler is in, we always send the request to > > dispatch list if .queue_rq() return busy. After mq IO scheduler > > is introduced, we only do this way when scheduler is used in > > case of direct issue. Actually we can do that when scheduler > > isn't used too. > > > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > --- > > block/blk-mq.c | 18 +++++++++++++++--- > > 1 file changed, 15 insertions(+), 3 deletions(-) > > > > diff --git a/block/blk-mq.c b/block/blk-mq.c > > index 041f7b7fa0d6..6e0fc80aa151 100644 > > --- a/block/blk-mq.c > > +++ b/block/blk-mq.c > > @@ -1463,6 +1463,16 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq) > > return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true); > > } > > > > +static void blk_mq_direct_dispatch(struct blk_mq_hw_ctx *hctx, > > + struct request *rq) > > +{ > > + spin_lock(&hctx->lock); > > + list_add(&rq->queuelist, &hctx->dispatch); > > + spin_unlock(&hctx->lock); > > + > > + blk_mq_run_hw_queue(hctx, false); > > +} > > + > > static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, > > struct request *rq, > > blk_qc_t *cookie, bool may_sleep) > > @@ -1499,15 +1509,17 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, > > switch (ret) { > > case BLK_STS_OK: > > *cookie = new_cookie; > > - return; > > + break; > > case BLK_STS_RESOURCE: > > __blk_mq_requeue_request(rq); > > - goto insert; > > + blk_mq_direct_dispatch(hctx, rq); > > + break; > > default: > > *cookie = BLK_QC_T_NONE; > > blk_mq_end_request(rq, ret); > > - return; > > + break; > > } > > + return; > > > > insert: > > blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep); > > Hello Ming, > > This patch changes the behavior of blk_mq_try_issue_directly() if a scheduler > has been configured and .queue_rq() returns BLK_STS_RESOURCE, namely by skipping > the e->type->ops.mq.insert_requests() call. Sorry but I don't think this is what > we want. It does not change behaviour for scheduler, please see blk_mq_sched_bypass_insert() which is called from blk_mq_sched_insert_request().
diff --git a/block/blk-mq.c b/block/blk-mq.c index 041f7b7fa0d6..6e0fc80aa151 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1463,6 +1463,16 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq) return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true); } +static void blk_mq_direct_dispatch(struct blk_mq_hw_ctx *hctx, + struct request *rq) +{ + spin_lock(&hctx->lock); + list_add(&rq->queuelist, &hctx->dispatch); + spin_unlock(&hctx->lock); + + blk_mq_run_hw_queue(hctx, false); +} + static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, struct request *rq, blk_qc_t *cookie, bool may_sleep) @@ -1499,15 +1509,17 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, switch (ret) { case BLK_STS_OK: *cookie = new_cookie; - return; + break; case BLK_STS_RESOURCE: __blk_mq_requeue_request(rq); - goto insert; + blk_mq_direct_dispatch(hctx, rq); + break; default: *cookie = BLK_QC_T_NONE; blk_mq_end_request(rq, ret); - return; + break; } + return; insert: blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep);
Before mq IO scheduler is in, we always send the request to dispatch list if .queue_rq() return busy. After mq IO scheduler is introduced, we only do this way when scheduler is used in case of direct issue. Actually we can do that when scheduler isn't used too. Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/blk-mq.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)