diff mbox series

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

Message ID 20210512131545.495160-12-hch@lst.de (mailing list archive)
State New, archived
Headers show
Series [01/15] direct-io: remove blk_poll support | expand

Commit Message

Christoph Hellwig May 12, 2021, 1:15 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
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: 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(-)

Comments

Sagi Grimberg May 12, 2021, 9:58 p.m. UTC | #1 
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
diff mbox series

Patch

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;