From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig , "Kirill A . Shutemov" , Ming Lei , Jens Axboe Subject: [PATCH 40/60] blk-merge: compute bio->bi_seg_front_size efficiently Date: Sat, 29 Oct 2016 16:08:39 +0800 Message-Id: <1477728600-12938-41-git-send-email-tom.leiming@gmail.com> In-Reply-To: <1477728600-12938-1-git-send-email-tom.leiming@gmail.com> References: <1477728600-12938-1-git-send-email-tom.leiming@gmail.com> List-ID: It is enough to check and compute bio->bi_seg_front_size just after the 1st segment is found, but current code checks that for each bvec, which is inefficient. This patch follows the way in __blk_recalc_rq_segments() for computing bio->bi_seg_front_size, and it is more efficient and code becomes more readable too. Signed-off-by: Ming Lei --- block/blk-merge.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 266c94d1d82f..465d9c65cb41 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -157,22 +157,21 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bvprvp = &bvprv; sectors += bv.bv_len >> 9; - if (nsegs == 1 && seg_size > front_seg_size) - front_seg_size = seg_size; continue; } new_segment: if (nsegs == queue_max_segments(q)) goto split; + if (nsegs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; + nsegs++; bvprv = bv; bvprvp = &bvprv; seg_size = bv.bv_len; sectors += bv.bv_len >> 9; - if (nsegs == 1 && seg_size > front_seg_size) - front_seg_size = seg_size; } do_split = false; @@ -185,6 +184,8 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bio = new; } + if (nsegs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; bio->bi_seg_front_size = front_seg_size; if (seg_size > bio->bi_seg_back_size) bio->bi_seg_back_size = seg_size; -- 2.7.4