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bio: optimize initialization of a bio 

The memset() used is measurably slower in targeted benchmarks, wasting
about 1% of the total runtime, or 50% of the (later) hot path cached
bio alloc. Get rid of it and fill in the bio manually.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-08-11 09:20:04 -06:00
parent fd08e5309b
commit da521626ac
1 changed files with 30 additions and 2 deletions
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32
block/bio.c
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@ -246,12 +246,40 @@ static void bio_free(struct bio *bio)
void bio_init(struct bio *bio, struct bio_vec *table,
unsigned short max_vecs)
{
memset(bio, 0, sizeof(*bio));
bio->bi_next = NULL;
bio->bi_bdev = NULL;
bio->bi_opf = 0;
bio->bi_flags = 0;
bio->bi_ioprio = 0;
bio->bi_write_hint = 0;
bio->bi_status = 0;
bio->bi_iter.bi_sector = 0;
bio->bi_iter.bi_size = 0;
bio->bi_iter.bi_idx = 0;
bio->bi_iter.bi_bvec_done = 0;
bio->bi_end_io = NULL;
bio->bi_private = NULL;
#ifdef CONFIG_BLK_CGROUP
bio->bi_blkg = NULL;
bio->bi_issue.value = 0;
#ifdef CONFIG_BLK_CGROUP_IOCOST
bio->bi_iocost_cost = 0;
#endif
#endif
#ifdef CONFIG_BLK_INLINE_ENCRYPTION
bio->bi_crypt_context = NULL;
#endif
#ifdef CONFIG_BLK_DEV_INTEGRITY
bio->bi_integrity = NULL;
#endif
bio->bi_vcnt = 0;
atomic_set(&bio->__bi_remaining, 1);
atomic_set(&bio->__bi_cnt, 1);
bio->bi_io_vec = table;
bio->bi_max_vecs = max_vecs;
bio->bi_io_vec = table;
bio->bi_pool = NULL;
}
EXPORT_SYMBOL(bio_init);