From 4b570521be54666e6ad7e5f47af92fd609fbd8b5 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 29 May 2014 11:00:11 -0600 Subject: [PATCH] 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: Jens Axboe --- block/blk-mq.c | 26 +++++++++----------------- 1 file changed, 9 insertions(+), 17 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index f98d977fd150..6160128085fc 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -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; @@ -449,8 +435,10 @@ 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. */ - set_bit(REQ_ATOM_STARTED, &rq->atomic_flags); - clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags); + 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)) { /* @@ -1112,7 +1100,11 @@ 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); - blk_account_io_start(rq, 1); + + 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,