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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 <axboe@fb.com>
This commit is contained in:
Jens Axboe 2014-05-29 11:00:11 -06:00
parent 05f1dd5315
commit 4b570521be
1 changed files with 9 additions and 17 deletions
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26
block/blk-mq.c
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@ -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,