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block: define 'struct bvec_iter' as packed

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'struct bvec_iter' is embedded into 'struct bio', define it as packed
so that we can get one extra 4bytes for other uses without expanding
bio.

'struct bvec_iter' is often allocated on stack, so making it packed
doesn't affect performance. Also I have run io_uring on both
nvme/null_blk, and not observe performance effect in this way.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2021-10-12 13:12:23 +02:00 committed by Jens Axboe
parent 1a7e76e4f1
commit 19416123ab
1 changed files with 1 additions and 1 deletions
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2
include/linux/bvec.h
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@ -44,7 +44,7 @@ struct bvec_iter {
unsigned int bi_bvec_done; /* number of bytes completed in unsigned int bi_bvec_done; /* number of bytes completed in
current bvec */ current bvec */
}; } __packed;
struct bvec_iter_all { struct bvec_iter_all {
struct bio_vec bv; struct bio_vec bv;