From: Jens Axboe Date: Tue, 28 Jul 2015 19:14:32 +0000 (-0600) Subject: block: shrink struct bio down to 2 cache lines again X-Git-Tag: omap-for-v4.3/fixes-rc1~114^2~19 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2c68f6dc6e621153a708bef6c569805762da2020;p=pandora-kernel.git 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 --- 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 { Reading git-diff-tree failed