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Commit 4b570521 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-mq: request initialization optimizations 



We currently clear a lot more than we need to, so make that a bit
more clever. Make some of the init dependent on features, like
only setting start_time if we are going to use it.

Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 05f1dd53

block/blk-mq.c

+9 −17
Original line number Diff line number Diff line
@@ -199,19 +199,12 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx, 
	rq->q = q;

	rq->mq_ctx = ctx;

	rq->cmd_flags |= rw_flags;

	rq->cmd_type = 0;

	/* do not touch atomic flags, it needs atomic ops against the timer */

	rq->cpu = -1;

	rq->__data_len = 0;

	rq->__sector = (sector_t) -1;

	rq->bio = NULL;

	rq->biotail = NULL;

	INIT_HLIST_NODE(&rq->hash);

	RB_CLEAR_NODE(&rq->rb_node);

	memset(&rq->flush, 0, max(sizeof(rq->flush), sizeof(rq->elv)));

	rq->rq_disk = NULL;

	rq->part = NULL;

	rq->start_time = jiffies;

#ifdef CONFIG_BLK_CGROUP

	rq->rl = NULL;

	set_start_time_ns(rq);
@@ -221,23 +214,16 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx, 
#if defined(CONFIG_BLK_DEV_INTEGRITY)

	rq->nr_integrity_segments = 0;

#endif

	rq->ioprio = 0;

	rq->special = NULL;

	/* tag was already set */

	rq->errors = 0;

	memset(rq->__cmd, 0, sizeof(rq->__cmd));

	rq->cmd = rq->__cmd;

	rq->cmd_len = BLK_MAX_CDB;



	rq->extra_len = 0;

	rq->sense_len = 0;

	rq->resid_len = 0;

	rq->sense = NULL;



	rq->deadline = 0;

	INIT_LIST_HEAD(&rq->timeout_list);

	rq->timeout = 0;

	rq->retries = 0;

	rq->end_io = NULL;

	rq->end_io_data = NULL;

	rq->next_rq = NULL;
@@ -449,7 +435,9 @@ static void blk_mq_start_request(struct request *rq, bool last) 
	 * complete. So be sure to clear complete again when we start

	 * the request, otherwise we'll ignore the completion event.

	 */

	if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))

		set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);

	if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))

		clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);



	if (q->dma_drain_size && blk_rq_bytes(rq)) {
@@ -1112,8 +1100,12 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) 
static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)

{

	init_request_from_bio(rq, bio);



	if (blk_do_io_stat(rq)) {

		rq->start_time = jiffies;

		blk_account_io_start(rq, 1);

	}

}



static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,

					 struct blk_mq_ctx *ctx,