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block: enable bio caching use for passthru IO 

bdev based polled O_DIRECT is currently quite a bit faster than
passthru on the same device, and one of the reaons is that we're not
able to use the bio caching for passthru IO.

If REQ_POLLED is set on the request, use the fs bio set for grabbing a
bio from the caches, if available. This saves 5-6% of CPU over head
for polled passthru IO.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2022-08-05 16:43:09 -06:00
parent f5d632d15e
commit 8af870aa5b
1 changed files with 25 additions and 8 deletions
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33
block/blk-map.c
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@ -231,6 +231,16 @@ out_bmd:
return ret;
}
static void bio_map_put(struct bio *bio)
{
if (bio->bi_opf & REQ_ALLOC_CACHE) {
bio_put(bio);
} else {
bio_uninit(bio);
kfree(bio);
}
}
static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
gfp_t gfp_mask)
{
@ -243,10 +253,19 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
if (!iov_iter_count(iter))
return -EINVAL;
bio = bio_kmalloc(nr_vecs, gfp_mask);
if (!bio)
return -ENOMEM;
bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
if (rq->cmd_flags & REQ_POLLED) {
blk_opf_t opf = rq->cmd_flags | REQ_ALLOC_CACHE;
bio = bio_alloc_bioset(NULL, nr_vecs, opf, gfp_mask,
&fs_bio_set);
if (!bio)
return -ENOMEM;
} else {
bio = bio_kmalloc(nr_vecs, gfp_mask);
if (!bio)
return -ENOMEM;
bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
}
while (iov_iter_count(iter)) {
struct page **pages;
@ -305,8 +324,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
out_unmap:
bio_release_pages(bio, false);
bio_uninit(bio);
kfree(bio);
bio_map_put(bio);
return ret;
}
@ -611,8 +629,7 @@ int blk_rq_unmap_user(struct bio *bio)
next_bio = bio;
bio = bio->bi_next;
bio_uninit(next_bio);
kfree(next_bio);
bio_map_put(next_bio);
}
return ret;