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authorJens Axboe <axboe@fb.com>2014-05-29 19:00:11 +0200
committerJens Axboe <axboe@fb.com>2014-05-29 19:00:11 +0200
commit4b570521be54666e6ad7e5f47af92fd609fbd8b5 (patch)
treefca8d28ad96f8857ea2f2c88b9301a38eeaf016b /block
parentblock: add queue flag for disabling SG merging (diff)
downloadlinux-4b570521be54666e6ad7e5f47af92fd609fbd8b5.tar.xz
linux-4b570521be54666e6ad7e5f47af92fd609fbd8b5.zip
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>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c26
1 files 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,