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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=unavailable 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 3F96DC04EBF for ; Thu, 15 Nov 2018 21:05:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F3FF2145D for ; Thu, 15 Nov 2018 21:05:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F3FF2145D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389034AbeKPHOs (ORCPT ); Fri, 16 Nov 2018 02:14:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50744 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725809AbeKPHOs (ORCPT ); Fri, 16 Nov 2018 02:14:48 -0500 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 B331FC04B2C8; Thu, 15 Nov 2018 21:05:20 +0000 (UTC) Received: from localhost (unknown [10.18.25.149]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1949E5D739; Thu, 15 Nov 2018 21:05:11 +0000 (UTC) Date: Thu, 15 Nov 2018 16:05:10 -0500 From: Mike Snitzer To: Omar Sandoval Cc: Ming Lei , Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Kent Overstreet , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, Shaohua Li , linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , Theodore Ts'o , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com Subject: Re: [PATCH V10 03/19] block: use bio_for_each_bvec() to compute multi-page bvec count Message-ID: <20181115210510.GA24908@redhat.com> References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-4-ming.lei@redhat.com> <20181115202028.GC9348@vader> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181115202028.GC9348@vader> User-Agent: Mutt/1.5.21 (2010-09-15) 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 [10.5.110.32]); Thu, 15 Nov 2018 21:05:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 15 2018 at 3:20pm -0500, Omar Sandoval wrote: > On Thu, Nov 15, 2018 at 04:52:50PM +0800, Ming Lei wrote: > > First it is more efficient to use bio_for_each_bvec() in both > > blk_bio_segment_split() and __blk_recalc_rq_segments() to compute how > > many multi-page bvecs there are in the bio. > > > > Secondly once bio_for_each_bvec() is used, the bvec may need to be > > splitted because its length can be very longer than max segment size, > > so we have to split the big bvec into several segments. > > > > Thirdly when splitting multi-page bvec into segments, the max segment > > limit may be reached, so the bio split need to be considered under > > this situation too. > > > > Cc: Dave Chinner > > Cc: Kent Overstreet > > Cc: Mike Snitzer > > Cc: dm-devel@redhat.com > > Cc: Alexander Viro > > Cc: linux-fsdevel@vger.kernel.org > > Cc: Shaohua Li > > Cc: linux-raid@vger.kernel.org > > Cc: linux-erofs@lists.ozlabs.org > > Cc: David Sterba > > Cc: linux-btrfs@vger.kernel.org > > Cc: Darrick J. Wong > > Cc: linux-xfs@vger.kernel.org > > Cc: Gao Xiang > > Cc: Christoph Hellwig > > Cc: Theodore Ts'o > > Cc: linux-ext4@vger.kernel.org > > Cc: Coly Li > > Cc: linux-bcache@vger.kernel.org > > Cc: Boaz Harrosh > > Cc: Bob Peterson > > Cc: cluster-devel@redhat.com > > Signed-off-by: Ming Lei > > --- > > block/blk-merge.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++--------- > > 1 file changed, 76 insertions(+), 14 deletions(-) > > > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index 91b2af332a84..6f7deb94a23f 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -160,6 +160,62 @@ static inline unsigned get_max_io_size(struct request_queue *q, > > return sectors; > > } > > > > +/* > > + * Split the bvec @bv into segments, and update all kinds of > > + * variables. > > + */ > > +static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv, > > + unsigned *nsegs, unsigned *last_seg_size, > > + unsigned *front_seg_size, unsigned *sectors) > > +{ > > + bool need_split = false; > > + unsigned len = bv->bv_len; > > + unsigned total_len = 0; > > + unsigned new_nsegs = 0, seg_size = 0; > > "unsigned int" here and everywhere else. Curious why? I've wondered what govens use of "unsigned" vs "unsigned int" recently and haven't found _the_ reason to pick one over the other. Thanks, Mike