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Commit 9bddeb2a authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-mq: make per-sw-queue bio merge as default .bio_merge 



Because what the per-sw-queue bio merge does is basically same with
scheduler's .bio_merge(), this patch makes per-sw-queue bio merge
as the default .bio_merge if no scheduler is used or io scheduler
doesn't provide .bio_merge().

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent ab42f35d

block/blk-mq-sched.c

+57 −5
Original line number Diff line number Diff line
@@ -221,19 +221,71 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 
}

EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);



/*

 * Reverse check our software queue for entries that we could potentially

 * merge with. Currently includes a hand-wavy stop count of 8, to not spend

 * too much time checking for merges.

 */

static bool blk_mq_attempt_merge(struct request_queue *q,

				 struct blk_mq_ctx *ctx, struct bio *bio)

{

	struct request *rq;

	int checked = 8;



	list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {

		bool merged = false;



		if (!checked--)

			break;



		if (!blk_rq_merge_ok(rq, bio))

			continue;



		switch (blk_try_merge(rq, bio)) {

		case ELEVATOR_BACK_MERGE:

			if (blk_mq_sched_allow_merge(q, rq, bio))

				merged = bio_attempt_back_merge(q, rq, bio);

			break;

		case ELEVATOR_FRONT_MERGE:

			if (blk_mq_sched_allow_merge(q, rq, bio))

				merged = bio_attempt_front_merge(q, rq, bio);

			break;

		case ELEVATOR_DISCARD_MERGE:

			merged = bio_attempt_discard_merge(q, rq, bio);

			break;

		default:

			continue;

		}



		if (merged)

			ctx->rq_merged++;

		return merged;

	}



	return false;

}



bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)

{

	struct elevator_queue *e = q->elevator;



	if (e->type->ops.mq.bio_merge) {

	struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);

	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);

	bool ret = false;



	if (e && e->type->ops.mq.bio_merge) {

		blk_mq_put_ctx(ctx);

		return e->type->ops.mq.bio_merge(hctx, bio);

	}



	return false;

	if (hctx->flags & BLK_MQ_F_SHOULD_MERGE) {

		/* default per sw-queue merge */

		spin_lock(&ctx->lock);

		ret = blk_mq_attempt_merge(q, ctx, bio);

		spin_unlock(&ctx->lock);

	}



	blk_mq_put_ctx(ctx);

	return ret;

}



bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)

block/blk-mq-sched.h

+1 −3
Original line number Diff line number Diff line
@@ -38,9 +38,7 @@ int blk_mq_sched_init(struct request_queue *q); 
static inline bool

blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)

{

	struct elevator_queue *e = q->elevator;



	if (!e || blk_queue_nomerges(q) || !bio_mergeable(bio))

	if (blk_queue_nomerges(q) || !bio_mergeable(bio))

		return false;



	return __blk_mq_sched_bio_merge(q, bio);

block/blk-mq.c

+0 −64
Original line number Diff line number Diff line
@@ -753,50 +753,6 @@ static void blk_mq_timeout_work(struct work_struct *work) 
	blk_queue_exit(q);

}



/*

 * Reverse check our software queue for entries that we could potentially

 * merge with. Currently includes a hand-wavy stop count of 8, to not spend

 * too much time checking for merges.

 */

static bool blk_mq_attempt_merge(struct request_queue *q,

				 struct blk_mq_ctx *ctx, struct bio *bio)

{

	struct request *rq;

	int checked = 8;



	list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {

		bool merged = false;



		if (!checked--)

			break;



		if (!blk_rq_merge_ok(rq, bio))

			continue;



		switch (blk_try_merge(rq, bio)) {

		case ELEVATOR_BACK_MERGE:

			if (blk_mq_sched_allow_merge(q, rq, bio))

				merged = bio_attempt_back_merge(q, rq, bio);

			break;

		case ELEVATOR_FRONT_MERGE:

			if (blk_mq_sched_allow_merge(q, rq, bio))

				merged = bio_attempt_front_merge(q, rq, bio);

			break;

		case ELEVATOR_DISCARD_MERGE:

			merged = bio_attempt_discard_merge(q, rq, bio);

			break;

		default:

			continue;

		}



		if (merged)

			ctx->rq_merged++;

		return merged;

	}



	return false;

}



struct flush_busy_ctx_data {

	struct blk_mq_hw_ctx *hctx;

	struct list_head *list;
@@ -1427,23 +1383,6 @@ static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx) 
		!blk_queue_nomerges(hctx->queue);

}



/* attempt to merge bio into current sw queue */

static inline bool blk_mq_merge_bio(struct request_queue *q, struct bio *bio)

{

	bool ret = false;

	struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);

	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);



	if (hctx_allow_merges(hctx) && bio_mergeable(bio)) {

		spin_lock(&ctx->lock);

		ret = blk_mq_attempt_merge(q, ctx, bio);

		spin_unlock(&ctx->lock);

	}



	blk_mq_put_ctx(ctx);

	return ret;

}



static inline void blk_mq_queue_io(struct blk_mq_hw_ctx *hctx,

				   struct blk_mq_ctx *ctx,

				   struct request *rq)
@@ -1549,9 +1488,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) 
	if (blk_mq_sched_bio_merge(q, bio))

		return BLK_QC_T_NONE;



	if (blk_mq_merge_bio(q, bio))

		return BLK_QC_T_NONE;



	wb_acct = wbt_wait(q->rq_wb, bio, NULL);



	trace_block_getrq(q, bio, bio->bi_opf);