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authorJens Axboe <axboe@kernel.dk>2018-01-10 11:46:39 -0700
committerJens Axboe <axboe@kernel.dk>2018-01-10 11:47:58 -0700
commit7c3fb70f0341f9d924818e648906774921f4bcb3 (patch)
tree6f6eac29e2d0312784dc8e568c303e02391f3726 /block
parente14575b3d457f5806d79b85886ef94d9c29e3b2a (diff)
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block: rearrange a few request fields for better cache layout
Move completion related items (like the call single data) near the end of the struct, instead of mixing them in with the initial queueing related fields. Move queuelist below the bio structures. Then we have all queueing related bits in the first cache line. This yields a 1.5-2% increase in IOPS for a null_blk test, both for sync and for high thread count access. Sync test goes form 975K to 992K, 32-thread case from 20.8M to 21.2M IOPS. Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c18
1 files changed, 9 insertions, 9 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 87e6b10c8ecb..435a5a0d441f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -270,8 +270,6 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
struct request *rq = tags->static_rqs[tag];
- rq->rq_flags = 0;
-
if (data->flags & BLK_MQ_REQ_INTERNAL) {
rq->tag = -1;
rq->internal_tag = tag;
@@ -285,26 +283,22 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
data->hctx->tags->rqs[rq->tag] = rq;
}
- INIT_LIST_HEAD(&rq->queuelist);
/* csd/requeue_work/fifo_time is initialized before use */
rq->q = data->q;
rq->mq_ctx = data->ctx;
+ rq->rq_flags = 0;
+ rq->cpu = -1;
rq->cmd_flags = op;
if (data->flags & BLK_MQ_REQ_PREEMPT)
rq->rq_flags |= RQF_PREEMPT;
if (blk_queue_io_stat(data->q))
rq->rq_flags |= RQF_IO_STAT;
- rq->cpu = -1;
+ INIT_LIST_HEAD(&rq->queuelist);
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->rq_disk = NULL;
rq->part = NULL;
rq->start_time = jiffies;
-#ifdef CONFIG_BLK_CGROUP
- rq->rl = NULL;
- set_start_time_ns(rq);
- rq->io_start_time_ns = 0;
-#endif
rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
rq->nr_integrity_segments = 0;
@@ -321,6 +315,12 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
rq->end_io_data = NULL;
rq->next_rq = NULL;
+#ifdef CONFIG_BLK_CGROUP
+ rq->rl = NULL;
+ set_start_time_ns(rq);
+ rq->io_start_time_ns = 0;
+#endif
+
data->ctx->rq_dispatched[op_is_sync(op)]++;
return rq;
}