On 4/22/21 2:20 PM, Ming Lei wrote:
'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@xxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
include/linux/bvec.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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;
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Cheers,
Hannes
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