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| author | Jens Axboe <axboe@fb.com> | 2015-07-28 13:14:32 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-07-29 08:55:25 -0600 |
| commit | 2c68f6dc6e621153a708bef6c569805762da2020 (patch) | |
| tree | f5232fa96a9049981479daf8e2d5818f70878a28 | |
| parent | b7c44ed9d2fc6b461378c65eaf144ccc80a47772 (diff) | |
| download | linux-2c68f6dc6e621153a708bef6c569805762da2020.tar.bz2 | |
block: shrink struct bio down to 2 cache lines again
Commit bcf2843b3f8f added ->bi_error to cleanup the error passing
for struct bio, but that ended up adding 4 bytes and a 4 byte hole
to the size of struct bio. For a clean config, that bumped it from
128 bytes, to 136 bytes, on x86-64.
The ->bi_flags member is currently an unsigned long, but it fits
easily within an int. Change it to an unsigned int, adjust the
the pool offset code, and move ->bi_error into the new hole. Then
we end up with a 128 byte bio again.
Change the bio flag set/clear to use cmpxchg to ensure we don't
lose any flags when manipulating them.
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | include/linux/bio.h | 6 | ||||
| -rw-r--r-- | include/linux/blk_types.h | 6 |
2 files changed, 6 insertions, 6 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h index 986e6e19feb5..b7892a1906bd 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -306,17 +306,17 @@ static inline void bio_cnt_set(struct bio *bio, unsigned int count) static inline bool bio_flagged(struct bio *bio, unsigned int bit) { - return (bio->bi_flags & (1UL << bit)) != 0; + return (bio->bi_flags & (1U << bit)) != 0; } static inline void bio_set_flag(struct bio *bio, unsigned int bit) { - bio->bi_flags |= (1UL << bit); + bio->bi_flags |= (1U << bit); } static inline void bio_clear_flag(struct bio *bio, unsigned int bit) { - bio->bi_flags &= ~(1UL << bit); + bio->bi_flags &= ~(1U << bit); } enum bip_flags { diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index a765a50e780f..4b7b4ebaa633 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -46,14 +46,14 @@ struct bvec_iter { struct bio { struct bio *bi_next; /* request queue link */ struct block_device *bi_bdev; - unsigned long bi_flags; /* status, command, etc */ + unsigned int bi_flags; /* status, command, etc */ + int bi_error; unsigned long bi_rw; /* bottom bits READ/WRITE, * top bits priority */ struct bvec_iter bi_iter; - int bi_error; /* Number of segments in this BIO after * physical address coalescing is performed. */ @@ -134,7 +134,7 @@ struct bio { */ #define BIO_POOL_BITS (4) #define BIO_POOL_NONE ((1UL << BIO_POOL_BITS) - 1) -#define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS) +#define BIO_POOL_OFFSET (32 - BIO_POOL_BITS) #define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET) #define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET) |