diff options
| author | Jens Axboe <axboe@kernel.dk> | 2021-10-06 06:34:11 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-10-18 06:17:03 -0600 |
| commit | 47c122e35d7e43b14129ceb9ed3a7e67599978fa (patch) | |
| tree | a5c654c821d3b1bc49595a2e442d3ae3825e4919 /block/blk-mq.h | |
| parent | ba0ffdd8ce48ad7f7e85191cd29f9674caca3745 (diff) | |
block: pre-allocate requests if plug is started and is a batch
The caller typically has a good (or even exact) idea of how many requests
it needs to submit. We can make the request/tag allocation a lot more
efficient if we just allocate N requests/tags upfront when we queue the
first bio from the batch.
Provide a new plug start helper that allows the caller to specify how many
IOs are expected. This sets plug->nr_ios, and we can use that for smarter
request allocation. The plug provides a holding spot for requests, and
request allocation will check it before calling into the normal request
allocation path.
The blk_finish_plug() is called, check if there are unused requests and
free them. This should not happen in normal operations. The exception is
if we get merging, then we may be left with requests that need freeing
when done.
This raises the per-core performance on my setup from ~5.8M to ~6.1M
IOPS.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-mq.h')
| -rw-r--r-- | block/blk-mq.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/block/blk-mq.h b/block/blk-mq.h index 171e8cdcff54..5da970bb8865 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -125,6 +125,7 @@ extern int __blk_mq_register_dev(struct device *dev, struct request_queue *q); extern int blk_mq_sysfs_register(struct request_queue *q); extern void blk_mq_sysfs_unregister(struct request_queue *q); extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx); +void blk_mq_free_plug_rqs(struct blk_plug *plug); void blk_mq_release(struct request_queue *q); @@ -152,6 +153,10 @@ struct blk_mq_alloc_data { unsigned int shallow_depth; unsigned int cmd_flags; + /* allocate multiple requests/tags in one go */ + unsigned int nr_tags; + struct request **cached_rq; + /* input & output parameter */ struct blk_mq_ctx *ctx; struct blk_mq_hw_ctx *hctx; |