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[11/15] block: define 'struct bvec_iter' as packed

Message ID 20210427161619.1294399-12-hch@lst.de (mailing list archive)
State New
Headers show
Series [01/15] direct-io: remove blk_poll support | expand

Commit Message

Christoph Hellwig April 27, 2021, 4:16 p.m. UTC
From: Ming Lei <ming.lei@redhat.com>

'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

'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: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
 include/linux/bvec.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series


diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index ff832e698efb..a0c4f41dfc83 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -43,7 +43,7 @@  struct bvec_iter {
 	unsigned int            bi_bvec_done;	/* number of bytes completed in
 						   current bvec */
+} __packed;
 struct bvec_iter_all {
 	struct bio_vec	bv;