@@ -1478,11 +1478,6 @@ static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
blk_mq_sched_insert_request(rq, false, true, true, false);
}
-/*
- * Multiple hardware queue variant. This will not use per-process plugs,
- * but will attempt to bypass the hctx queueing if we can go straight to
- * hardware for SYNC IO.
- */
static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
const int is_sync = op_is_sync(bio->bi_opf);
@@ -1534,7 +1529,36 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
}
plug = current->plug;
- if (((plug && !blk_queue_nomerges(q)) || is_sync)) {
+ if (plug && q->nr_hw_queues == 1) {
+ struct request *last = NULL;
+
+ blk_mq_bio_to_request(rq, bio);
+
+ /*
+ * @request_count may become stale because of schedule
+ * out, so check the list again.
+ */
+ if (list_empty(&plug->mq_list))
+ request_count = 0;
+ else if (blk_queue_nomerges(q))
+ request_count = blk_plug_queued_count(q);
+
+ if (!request_count)
+ trace_block_plug(q);
+ else
+ last = list_entry_rq(plug->mq_list.prev);
+
+ blk_mq_put_ctx(data.ctx);
+
+ if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
+ blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
+ blk_flush_plug_list(plug, false);
+ trace_block_plug(q);
+ }
+
+ list_add_tail(&rq->queuelist, &plug->mq_list);
+ goto done;
+ } else if (((plug && !blk_queue_nomerges(q)) || is_sync)) {
struct request *old_rq = NULL;
blk_mq_bio_to_request(rq, bio);
@@ -1596,119 +1620,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
return cookie;
}
-/*
- * Single hardware queue variant. This will attempt to use any per-process
- * plug for merging and IO deferral.
- */
-static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
-{
- const int is_sync = op_is_sync(bio->bi_opf);
- const int is_flush_fua = op_is_flush(bio->bi_opf);
- struct blk_plug *plug;
- unsigned int request_count = 0;
- struct blk_mq_alloc_data data = { .flags = 0 };
- struct request *rq;
- blk_qc_t cookie;
- unsigned int wb_acct;
-
- blk_queue_bounce(q, &bio);
-
- if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
- bio_io_error(bio);
- return BLK_QC_T_NONE;
- }
-
- blk_queue_split(q, &bio, q->bio_split);
-
- if (!is_flush_fua && !blk_queue_nomerges(q)) {
- if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
- return BLK_QC_T_NONE;
- } else
- request_count = blk_plug_queued_count(q);
-
- if (blk_mq_sched_bio_merge(q, bio))
- return BLK_QC_T_NONE;
-
- wb_acct = wbt_wait(q->rq_wb, bio, NULL);
-
- trace_block_getrq(q, bio, bio->bi_opf);
-
- rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
- if (unlikely(!rq)) {
- __wbt_done(q->rq_wb, wb_acct);
- return BLK_QC_T_NONE;
- }
-
- wbt_track(&rq->issue_stat, wb_acct);
-
- cookie = request_to_qc_t(data.hctx, rq);
-
- if (unlikely(is_flush_fua)) {
- if (q->elevator)
- goto elv_insert;
- blk_mq_bio_to_request(rq, bio);
- blk_insert_flush(rq);
- goto run_queue;
- }
-
- /*
- * A task plug currently exists. Since this is completely lockless,
- * utilize that to temporarily store requests until the task is
- * either done or scheduled away.
- */
- plug = current->plug;
- if (plug) {
- struct request *last = NULL;
-
- blk_mq_bio_to_request(rq, bio);
-
- /*
- * @request_count may become stale because of schedule
- * out, so check the list again.
- */
- if (list_empty(&plug->mq_list))
- request_count = 0;
- if (!request_count)
- trace_block_plug(q);
- else
- last = list_entry_rq(plug->mq_list.prev);
-
- blk_mq_put_ctx(data.ctx);
-
- if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
- blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
- blk_flush_plug_list(plug, false);
- trace_block_plug(q);
- }
-
- list_add_tail(&rq->queuelist, &plug->mq_list);
- return cookie;
- }
-
- if (q->elevator) {
-elv_insert:
- blk_mq_put_ctx(data.ctx);
- blk_mq_bio_to_request(rq, bio);
- blk_mq_sched_insert_request(rq, false, true,
- !is_sync || is_flush_fua, true);
- goto done;
- }
- if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
- /*
- * For a SYNC request, send it to the hardware immediately. For
- * an ASYNC request, just ensure that we run it later on. The
- * latter allows for merging opportunities and more efficient
- * dispatching.
- */
-run_queue:
- blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
- }
-
- blk_mq_put_ctx(data.ctx);
-done:
- return cookie;
-}
-
void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
unsigned int hctx_idx)
{
@@ -2366,10 +2277,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
INIT_LIST_HEAD(&q->requeue_list);
spin_lock_init(&q->requeue_lock);
- if (q->nr_hw_queues > 1)
- blk_queue_make_request(q, blk_mq_make_request);
- else
- blk_queue_make_request(q, blk_sq_make_request);
+ blk_queue_make_request(q, blk_mq_make_request);
/*
* Do this after blk_queue_make_request() overrides it...
@@ -2717,16 +2625,6 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
set->nr_hw_queues = nr_hw_queues;
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_realloc_hw_ctxs(set, q);
-
- /*
- * Manually set the make_request_fn as blk_queue_make_request
- * resets a lot of the queue settings.
- */
- if (q->nr_hw_queues > 1)
- q->make_request_fn = blk_mq_make_request;
- else
- q->make_request_fn = blk_sq_make_request;
-
blk_mq_queue_reinit(q, cpu_online_mask);
}
They are mostly the same code anyway - this just one small conditional for the plug case that is different for both variants. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/blk-mq.c | 164 +++++++++++---------------------------------------------- 1 file changed, 31 insertions(+), 133 deletions(-)