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Commit bbcbbd56 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: optimize blk_bio_segment_split for single-page bvec 



Introduce a fast path for single-page bvec IO, then we can avoid
to call bvec_split_segs() unnecessarily.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 48d7727c

block/blk-merge.c

+9 −3
Original line number Diff line number Diff line
@@ -286,10 +286,16 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, 
		bvprv = bv;

		bvprvp = &bvprv;



		if (bvec_split_segs(q, &bv, &nsegs, &seg_size,

				    &front_seg_size, &sectors))

		if (bv.bv_offset + bv.bv_len <= PAGE_SIZE) {

			nsegs++;

			seg_size = bv.bv_len;

			sectors += bv.bv_len >> 9;

			if (nsegs == 1 && seg_size > front_seg_size)

				front_seg_size = seg_size;

		} else if (bvec_split_segs(q, &bv, &nsegs, &seg_size,

				    &front_seg_size, &sectors)) {

			goto split;



		}

	}



	do_split = false;