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block: ensure that struct blk_mq_alloc_data is fully initialized

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On x86, rep stos will be emitted to clear the the blk_mq_alloc_data
struct, as not all members are being explicitly initialied. Depending on
the type of CPU, this is a noticeable slowdown compared to just ensuring
that the struct is fully initialized when setup.

For the 4 spots that setup a struct blk_mq_alloc_data on the stack,
ensure all members are being initialized.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe
2025-04-15 08:48:06 -06:00
parent e093b784ab
commit 9b79f86e06
1 changed files with 21 additions and 1 deletions
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22
block/blk-mq.c
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@@ -584,9 +584,13 @@ static struct request *blk_mq_rq_cache_fill(struct request_queue *q,
struct blk_mq_alloc_data data = {
.q = q,
.flags = flags,
.shallow_depth = 0,
.cmd_flags = opf,
.rq_flags = 0,
.nr_tags = plug->nr_ios,
.cached_rqs = &plug->cached_rqs,
.ctx = NULL,
.hctx = NULL
};
struct request *rq;
@@ -646,8 +650,13 @@ struct request *blk_mq_alloc_request(struct request_queue *q, blk_opf_t opf,
struct blk_mq_alloc_data data = {
.q = q,
.flags = flags,
.shallow_depth = 0,
.cmd_flags = opf,
.rq_flags = 0,
.nr_tags = 1,
.cached_rqs = NULL,
.ctx = NULL,
.hctx = NULL
};
int ret;
@@ -675,8 +684,13 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
struct blk_mq_alloc_data data = {
.q = q,
.flags = flags,
.shallow_depth = 0,
.cmd_flags = opf,
.rq_flags = 0,
.nr_tags = 1,
.cached_rqs = NULL,
.ctx = NULL,
.hctx = NULL
};
u64 alloc_time_ns = 0;
struct request *rq;
@@ -2967,8 +2981,14 @@ static struct request *blk_mq_get_new_requests(struct request_queue *q,
{
struct blk_mq_alloc_data data = {
.q = q,
.nr_tags = 1,
.flags = 0,
.shallow_depth = 0,
.cmd_flags = bio->bi_opf,
.rq_flags = 0,
.nr_tags = 1,
.cached_rqs = NULL,
.ctx = NULL,
.hctx = NULL
};
struct request *rq;