diff options
| -rw-r--r-- | fs/bio.c | 27 | ||||
| -rw-r--r-- | include/linux/bio.h | 12 |
2 files changed, 34 insertions, 5 deletions
@@ -31,6 +31,12 @@ DEFINE_TRACE(block_split); +/* + * Test patch to inline a certain number of bi_io_vec's inside the bio + * itself, to shrink a bio data allocation from two mempool calls to one + */ +#define BIO_INLINE_VECS 4 + static mempool_t *bio_split_pool __read_mostly; /* @@ -241,7 +247,7 @@ void bio_free(struct bio *bio, struct bio_set *bs) { void *p; - if (bio->bi_io_vec) + if (bio_has_allocated_vec(bio)) bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio)); if (bio_integrity(bio)) @@ -267,7 +273,8 @@ static void bio_fs_destructor(struct bio *bio) static void bio_kmalloc_destructor(struct bio *bio) { - kfree(bio->bi_io_vec); + if (bio_has_allocated_vec(bio)) + kfree(bio->bi_io_vec); kfree(bio); } @@ -314,7 +321,16 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs) if (likely(nr_iovecs)) { unsigned long uninitialized_var(idx); - bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs); + if (nr_iovecs <= BIO_INLINE_VECS) { + idx = 0; + bvl = bio->bi_inline_vecs; + nr_iovecs = BIO_INLINE_VECS; + memset(bvl, 0, BIO_INLINE_VECS * sizeof(*bvl)); + } else { + bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, + bs); + nr_iovecs = bvec_nr_vecs(idx); + } if (unlikely(!bvl)) { if (bs) mempool_free(bio, bs->bio_pool); @@ -324,7 +340,7 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs) goto out; } bio->bi_flags |= idx << BIO_POOL_OFFSET; - bio->bi_max_vecs = bvec_nr_vecs(idx); + bio->bi_max_vecs = nr_iovecs; } bio->bi_io_vec = bvl; } @@ -1525,6 +1541,7 @@ void bioset_free(struct bio_set *bs) */ struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad) { + unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec); struct bio_set *bs; bs = kzalloc(sizeof(*bs), GFP_KERNEL); @@ -1533,7 +1550,7 @@ struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad) bs->front_pad = front_pad; - bs->bio_slab = bio_find_or_create_slab(front_pad); + bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad); if (!bs->bio_slab) { kfree(bs); return NULL; diff --git a/include/linux/bio.h b/include/linux/bio.h index 4b80d3537f97..18462c5b8fff 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -102,6 +102,13 @@ struct bio { #endif bio_destructor_t *bi_destructor; /* destructor */ + + /* + * We can inline a number of vecs at the end of the bio, to avoid + * double allocations for a small number of bio_vecs. This member + * MUST obviously be kept at the very end of the bio. + */ + struct bio_vec bi_inline_vecs[0]; }; /* @@ -213,6 +220,11 @@ static inline void *bio_data(struct bio *bio) return NULL; } +static inline int bio_has_allocated_vec(struct bio *bio) +{ + return bio->bi_io_vec && bio->bi_io_vec != bio->bi_inline_vecs; +} + /* * will die */ |