From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5D5BC43381 for ; Wed, 27 Feb 2019 12:40:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3BA22133D for ; Wed, 27 Feb 2019 12:40:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730177AbfB0Mkk (ORCPT ); Wed, 27 Feb 2019 07:40:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48222 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726419AbfB0Mkk (ORCPT ); Wed, 27 Feb 2019 07:40:40 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 186E730BEF1D; Wed, 27 Feb 2019 12:40:40 +0000 (UTC) Received: from localhost (ovpn-8-19.pek2.redhat.com [10.72.8.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2BF37183EF; Wed, 27 Feb 2019 12:40:35 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei Subject: [PATCH 2/4] block: optimize __blk_segment_map_sg() for single-page bvec Date: Wed, 27 Feb 2019 20:40:11 +0800 Message-Id: <20190227124013.4828-3-ming.lei@redhat.com> In-Reply-To: <20190227124013.4828-1-ming.lei@redhat.com> References: <20190227124013.4828-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 27 Feb 2019 12:40:40 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Introduce a fast path for single-page bvec IO, then blk_bvec_map_sg() can be avoided. Signed-off-by: Ming Lei --- block/blk-merge.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index c7e8a8273460..c1ad8abbd9d6 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -447,7 +447,7 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, return biovec_phys_mergeable(q, &end_bv, &nxt_bv); } -static struct scatterlist *blk_next_sg(struct scatterlist **sg, +static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, struct scatterlist *sglist) { if (!*sg) @@ -512,7 +512,12 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, (*sg)->length += nbytes; } else { new_segment: - (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg); + if (bvec->bv_offset + bvec->bv_len <= PAGE_SIZE) { + *sg = blk_next_sg(sg, sglist); + sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); + (*nsegs) += 1; + } else + (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg); } *bvprv = *bvec; } -- 2.9.5