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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Jeffle Xu <jefflexu@linux.alibaba.com>,
	Ming Lei <ming.lei@redhat.com>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	Keith Busch <kbusch@kernel.org>, Sagi Grimberg <sagi@grimberg.me>,
	"Wunderlich, Mark" <mark.wunderlich@intel.com>,
	"Vasudevan, Anil" <anil.vasudevan@intel.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Hannes Reinecke <hare@suse.de>
Subject: [PATCH 11/15] block: define 'struct bvec_iter' as packed
Date: Tue, 27 Apr 2021 18:16:15 +0200	[thread overview]
Message-ID: <20210427161619.1294399-12-hch@lst.de> (raw)
In-Reply-To: <20210427161619.1294399-1-hch@lst.de>

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(-)

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;
-- 
2.30.1


  parent reply	other threads:[~2021-04-27 16:21 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-27 16:16 switch block layer polling to a bio based model v2 Christoph Hellwig
2021-04-27 16:16 ` [PATCH 01/15] direct-io: remove blk_poll support Christoph Hellwig
2021-04-27 16:16 ` [PATCH 02/15] block: don't try to poll multi-bio I/Os in __blkdev_direct_IO Christoph Hellwig
2021-04-27 16:16 ` [PATCH 03/15] iomap: don't try to poll multi-bio I/Os in __iomap_dio_rw Christoph Hellwig
2021-04-27 16:16 ` [PATCH 04/15] blk-mq: factor out a blk_qc_to_hctx helper Christoph Hellwig
2021-04-27 16:16 ` [PATCH 05/15] blk-mq: factor out a "classic" poll helper Christoph Hellwig
2021-04-27 16:16 ` [PATCH 06/15] blk-mq: remove blk_qc_t_to_tag and blk_qc_t_is_internal Christoph Hellwig
2021-04-27 16:16 ` [PATCH 07/15] blk-mq: remove blk_qc_t_valid Christoph Hellwig
2021-04-27 16:16 ` [PATCH 08/15] io_uring: don't sleep when polling for I/O Christoph Hellwig
2021-04-27 16:16 ` [PATCH 09/15] block: rename REQ_HIPRI to REQ_POLLED Christoph Hellwig
2021-04-27 16:16 ` [PATCH 10/15] block: use SLAB_TYPESAFE_BY_RCU for the bio slab Christoph Hellwig
2021-04-27 16:16 ` Christoph Hellwig [this message]
2021-04-27 16:16 ` [PATCH 12/15] block: switch polling to be bio based Christoph Hellwig
2021-04-28  2:28   ` Ming Lei
2021-04-29  7:20     ` Christoph Hellwig
2021-04-29  7:36       ` Ming Lei
2021-04-29  9:50         ` Christoph Hellwig
2021-04-29 14:42           ` Ming Lei
2021-04-27 16:16 ` [PATCH 13/15] block: add a QUEUE_FLAG_POLL_CAPABLE flag Christoph Hellwig
2021-04-27 16:16 ` [PATCH 14/15] nvme-multipath: set QUEUE_FLAG_NOWAIT Christoph Hellwig
2021-04-28  2:32   ` Ming Lei
2021-04-29  7:27     ` Christoph Hellwig
2021-04-29  7:37       ` Ming Lei
2021-04-29  9:46         ` Christoph Hellwig
2021-05-06 21:23           ` Sagi Grimberg
2021-04-27 16:16 ` [PATCH 15/15] nvme-multipath: enable polled I/O Christoph Hellwig
2021-04-28  2:36   ` Ming Lei
2021-05-12 13:15 switch block layer polling to a bio based model v3 Christoph Hellwig
2021-05-12 13:15 ` [PATCH 11/15] block: define 'struct bvec_iter' as packed Christoph Hellwig
2021-05-12 21:58   ` Sagi Grimberg

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