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| author | Jens Axboe <jens.axboe@oracle.com> | 2008-12-23 12:42:54 +0100 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-12-29 08:29:50 +0100 |
| commit | 392ddc32982a5c661dd90dd49a3cb37f1c68b782 (patch) | |
| tree | 614b8e857a70ce479bcbbf24af66a56b7723efc8 /include/linux/bio.h | |
| parent | bb799ca0202a360fa74d5f17039b9100caebdde7 (diff) | |
| download | linux-stable-392ddc32982a5c661dd90dd49a3cb37f1c68b782.tar.gz | |
bio: add support for inlining a number of bio_vecs inside the bio
When we go and allocate a bio for IO, we actually do two allocations.
One for the bio itself, and one for the bi_io_vec that holds the
actual pages we are interested in.
This feature inlines a definable amount of io vecs inside the bio
itself, so we eliminate the bio_vec array allocation for IO's up
to a certain size. It defaults to 4 vecs, which is typically 16k
of IO.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include/linux/bio.h')
| -rw-r--r-- | include/linux/bio.h | 12 |
1 files changed, 12 insertions, 0 deletions
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 */ |