From patchwork Mon Jun 26 12:10:07 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 9809465 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 13C2D60209 for ; Mon, 26 Jun 2017 12:26:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1A3FE22B26 for ; Mon, 26 Jun 2017 12:26:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0EFB823B24; Mon, 26 Jun 2017 12:26:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AE91A22B26 for ; Mon, 26 Jun 2017 12:26:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752087AbdFZMQx (ORCPT ); Mon, 26 Jun 2017 08:16:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34324 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752130AbdFZMQv (ORCPT ); Mon, 26 Jun 2017 08:16:51 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DCFEC4E34C; Mon, 26 Jun 2017 12:16:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com DCFEC4E34C Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=ming.lei@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com DCFEC4E34C Received: from localhost (ovpn-12-86.pek2.redhat.com [10.72.12.86]) by smtp.corp.redhat.com (Postfix) with ESMTP id EFA5F7E0F4; Mon, 26 Jun 2017 12:16:40 +0000 (UTC) From: Ming Lei To: Jens Axboe , Christoph Hellwig , Huang Ying , Andrew Morton , Alexander Viro Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Ming Lei Subject: [PATCH v2 24/51] block: blk-merge: try to make front segments in full size Date: Mon, 26 Jun 2017 20:10:07 +0800 Message-Id: <20170626121034.3051-25-ming.lei@redhat.com> In-Reply-To: <20170626121034.3051-1-ming.lei@redhat.com> References: <20170626121034.3051-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Mon, 26 Jun 2017 12:16:51 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When merging one bvec into segment, if the bvec is too big to merge, current policy is to move the whole bvec into another new segment. This patchset changes the policy into trying to maximize size of front segments, that means in above situation, part of bvec is merged into current segment, and the remainder is put into next segment. This patch prepares for support multipage bvec because it can be quite common to see this case and we should try to make front segments in full size. Signed-off-by: Ming Lei --- block/blk-merge.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 5 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 821b9c206308..bf7a0fa0199f 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -108,6 +108,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); + unsigned advance = 0; bio_for_each_segment(bv, bio, iter) { /* @@ -133,12 +134,32 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, } if (bvprvp && blk_queue_cluster(q)) { - if (seg_size + bv.bv_len > queue_max_segment_size(q)) - goto new_segment; if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) goto new_segment; if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) goto new_segment; + if (seg_size + bv.bv_len > queue_max_segment_size(q)) { + /* + * On assumption is that initial value of + * @seg_size(equals to bv.bv_len) won't be + * bigger than max segment size, but will + * becomes false after multipage bvec comes. + */ + advance = queue_max_segment_size(q) - seg_size; + + if (advance > 0) { + seg_size += advance; + sectors += advance >> 9; + bv.bv_len -= advance; + bv.bv_offset += advance; + } + + /* + * Still need to put remainder of current + * bvec into a new segment. + */ + goto new_segment; + } seg_size += bv.bv_len; bvprv = bv; @@ -160,6 +181,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, seg_size = bv.bv_len; sectors += bv.bv_len >> 9; + /* restore the bvec for iterator */ + if (advance) { + bv.bv_len += advance; + bv.bv_offset -= advance; + advance = 0; + } } do_split = false; @@ -360,16 +387,29 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, { int nbytes = bvec->bv_len; + unsigned advance = 0; if (*sg && *cluster) { - if ((*sg)->length + nbytes > queue_max_segment_size(q)) - goto new_segment; - if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) goto new_segment; if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) goto new_segment; + /* + * try best to merge part of the bvec into previous + * segment and follow same policy with + * blk_bio_segment_split() + */ + if ((*sg)->length + nbytes > queue_max_segment_size(q)) { + advance = queue_max_segment_size(q) - (*sg)->length; + if (advance) { + (*sg)->length += advance; + bvec->bv_offset += advance; + bvec->bv_len -= advance; + } + goto new_segment; + } + (*sg)->length += nbytes; } else { new_segment: @@ -392,6 +432,10 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); (*nsegs)++; + + /* for making iterator happy */ + bvec->bv_offset -= advance; + bvec->bv_len += advance; } *bvprv = *bvec; }