| Message ID | 20200602091502.1822499-4-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blk-mq: support batching dispatch from scheduler | expand |
On 2020/06/02 18:15, Ming Lei wrote: > Move code for getting driver tag and budget into one helper, so > blk_mq_dispatch_rq_list gets a bit simplified, and easier to read. > > Meantime move updating of 'no_tag' and 'no_budget_available' into > the branch for handling partial dispatch because that is exactly > consumer of the two local variables. > > Also rename the parameter of 'got_budget' as 'ask_budget'. > > No functional change. > > Cc: Sagi Grimberg <sagi@grimberg.me> > Cc: Baolin Wang <baolin.wang7@gmail.com> > Cc: Christoph Hellwig <hch@infradead.org> > Reviewed-by: Sagi Grimberg <sagi@grimberg.me> > Reviewed-by: Christoph Hellwig <hch@infradead.org> > Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> > Tested-by: Baolin Wang <baolin.wang7@gmail.com> > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > block/blk-mq.c | 75 +++++++++++++++++++++++++++++++++----------------- > 1 file changed, 49 insertions(+), 26 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 723bc39507fe..ee9342aac7be 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -1233,18 +1233,51 @@ static void blk_mq_handle_zone_resource(struct request *rq, > __blk_mq_requeue_request(rq); > } > > +enum prep_dispatch { > + PREP_DISPATCH_OK, > + PREP_DISPATCH_NO_TAG, > + PREP_DISPATCH_NO_BUDGET, > +}; > + > +static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq, > + bool ask_budget) "need_budget" may be a better argument name instead of ask_budget. More reflective of the fact that this is a boolean. > +{ > + struct blk_mq_hw_ctx *hctx = rq->mq_hctx; > + > + if (ask_budget && !blk_mq_get_dispatch_budget(rq->q)) { > + blk_mq_put_driver_tag(rq); > + return PREP_DISPATCH_NO_BUDGET; > + } > + > + if (!blk_mq_get_driver_tag(rq)) { > + /* > + * The initial allocation attempt failed, so we need to > + * rerun the hardware queue when a tag is freed. The > + * waitqueue takes care of that. If the queue is run > + * before we add this entry back on the dispatch list, > + * we'll re-run it below. > + */ > + if (!blk_mq_mark_tag_wait(hctx, rq)) { > + /* budget is always obtained before getting tag */ This is clear since it was down a few lines above. Maybe drop this comment ? > + blk_mq_put_dispatch_budget(rq->q); > + return PREP_DISPATCH_NO_TAG; > + } > + } > + > + return PREP_DISPATCH_OK; > +} > + > /* > * Returns true if we did some work AND can potentially do more. > */ > bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, > bool got_budget) > { > + enum prep_dispatch prep; > struct request_queue *q = hctx->queue; > struct request *rq, *nxt; > - bool no_tag = false; > int errors, queued; > blk_status_t ret = BLK_STS_OK; > - bool no_budget_avail = false; > LIST_HEAD(zone_list); > > if (list_empty(list)) > @@ -1262,31 +1295,9 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, > rq = list_first_entry(list, struct request, queuelist); > > WARN_ON_ONCE(hctx != rq->mq_hctx); > - if (!got_budget && !blk_mq_get_dispatch_budget(q)) { > - blk_mq_put_driver_tag(rq); > - no_budget_avail = true; > + prep = blk_mq_prep_dispatch_rq(rq, !got_budget); > + if (prep != PREP_DISPATCH_OK) > break; > - } > - > - if (!blk_mq_get_driver_tag(rq)) { > - /* > - * The initial allocation attempt failed, so we need to > - * rerun the hardware queue when a tag is freed. The > - * waitqueue takes care of that. If the queue is run > - * before we add this entry back on the dispatch list, > - * we'll re-run it below. > - */ > - if (!blk_mq_mark_tag_wait(hctx, rq)) { > - blk_mq_put_dispatch_budget(q); > - /* > - * For non-shared tags, the RESTART check > - * will suffice. > - */ > - if (hctx->flags & BLK_MQ_F_TAG_SHARED) > - no_tag = true; > - break; > - } > - } > > list_del_init(&rq->queuelist); > > @@ -1339,6 +1350,18 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, > */ > if (!list_empty(list)) { > bool needs_restart; > + bool no_tag = false; > + bool no_budget_avail = false; > + > + /* > + * For non-shared tags, the RESTART check > + * will suffice. > + */ > + if (prep == PREP_DISPATCH_NO_TAG && > + (hctx->flags & BLK_MQ_F_TAG_SHARED)) > + no_tag = true; You could drop the variable declaration initialization and simply have: no_tag = prep == PREP_DISPATCH_NO_TAG && (hctx->flags & BLK_MQ_F_TAG_SHARED) > + if (prep == PREP_DISPATCH_NO_BUDGET) > + no_budget_avail = true; Same here: no_budget = prep == PREP_DISPATCH_NO_BUDGET; Also to be symmetric with "no_tag", "no_budget" may be a better variable name ? > > /* > * If we didn't flush the entire list, we could have told >
diff --git a/block/blk-mq.c b/block/blk-mq.c index 723bc39507fe..ee9342aac7be 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1233,18 +1233,51 @@ static void blk_mq_handle_zone_resource(struct request *rq, __blk_mq_requeue_request(rq); } +enum prep_dispatch { + PREP_DISPATCH_OK, + PREP_DISPATCH_NO_TAG, + PREP_DISPATCH_NO_BUDGET, +}; + +static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq, + bool ask_budget) +{ + struct blk_mq_hw_ctx *hctx = rq->mq_hctx; + + if (ask_budget && !blk_mq_get_dispatch_budget(rq->q)) { + blk_mq_put_driver_tag(rq); + return PREP_DISPATCH_NO_BUDGET; + } + + if (!blk_mq_get_driver_tag(rq)) { + /* + * The initial allocation attempt failed, so we need to + * rerun the hardware queue when a tag is freed. The + * waitqueue takes care of that. If the queue is run + * before we add this entry back on the dispatch list, + * we'll re-run it below. + */ + if (!blk_mq_mark_tag_wait(hctx, rq)) { + /* budget is always obtained before getting tag */ + blk_mq_put_dispatch_budget(rq->q); + return PREP_DISPATCH_NO_TAG; + } + } + + return PREP_DISPATCH_OK; +} + /* * Returns true if we did some work AND can potentially do more. */ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, bool got_budget) { + enum prep_dispatch prep; struct request_queue *q = hctx->queue; struct request *rq, *nxt; - bool no_tag = false; int errors, queued; blk_status_t ret = BLK_STS_OK; - bool no_budget_avail = false; LIST_HEAD(zone_list); if (list_empty(list)) @@ -1262,31 +1295,9 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, rq = list_first_entry(list, struct request, queuelist); WARN_ON_ONCE(hctx != rq->mq_hctx); - if (!got_budget && !blk_mq_get_dispatch_budget(q)) { - blk_mq_put_driver_tag(rq); - no_budget_avail = true; + prep = blk_mq_prep_dispatch_rq(rq, !got_budget); + if (prep != PREP_DISPATCH_OK) break; - } - - if (!blk_mq_get_driver_tag(rq)) { - /* - * The initial allocation attempt failed, so we need to - * rerun the hardware queue when a tag is freed. The - * waitqueue takes care of that. If the queue is run - * before we add this entry back on the dispatch list, - * we'll re-run it below. - */ - if (!blk_mq_mark_tag_wait(hctx, rq)) { - blk_mq_put_dispatch_budget(q); - /* - * For non-shared tags, the RESTART check - * will suffice. - */ - if (hctx->flags & BLK_MQ_F_TAG_SHARED) - no_tag = true; - break; - } - } list_del_init(&rq->queuelist); @@ -1339,6 +1350,18 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, */ if (!list_empty(list)) { bool needs_restart; + bool no_tag = false; + bool no_budget_avail = false; + + /* + * For non-shared tags, the RESTART check + * will suffice. + */ + if (prep == PREP_DISPATCH_NO_TAG && + (hctx->flags & BLK_MQ_F_TAG_SHARED)) + no_tag = true; + if (prep == PREP_DISPATCH_NO_BUDGET) + no_budget_avail = true; /* * If we didn't flush the entire list, we could have told