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=-3.8 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 18596ECDE44 for ; Fri, 26 Oct 2018 14:26:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D26172082D for ; Fri, 26 Oct 2018 14:26:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="I2JDpYJ9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D26172082D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk 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 S1727355AbeJZXDR (ORCPT ); Fri, 26 Oct 2018 19:03:17 -0400 Received: from mail-it1-f193.google.com ([209.85.166.193]:50989 "EHLO mail-it1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726179AbeJZXDQ (ORCPT ); Fri, 26 Oct 2018 19:03:16 -0400 Received: by mail-it1-f193.google.com with SMTP id k206-v6so1738576ite.0 for ; Fri, 26 Oct 2018 07:26:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=RxNeL0lPc2d1DxZeopg2s5tokZ+X47tKrxulYoOh5bc=; b=I2JDpYJ9qd/kVktTDOo780XDPBp93OLsesFTWNbt4O6zTQ1R8I1NOo25Z18b7zNV55 qTadBwji0e8XVxxOD1jZxanwUlcjsClKsgo5Hfd8egMz9ghf83cKl7zEAhUE4m3Z3WiJ L6PtcUN91Q8lpwQ/InfbVMTQ+1AerEobsQwoX5DxD7cLRuqsByaikEwi6gz5ME02OtFw gGksq8zHeFkQK1cGo6ZDwudwVyLi+cZcSWK6rCTE+Z5R+1nazO4cQ2jjOJ3epJtsE3st 4gA7ltj7jGu4MbH5fzjUHkr/Fd/rfDMc73Pe+gaeu0++EslQQzI8OsLlomDKcfZZJfsL owRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=RxNeL0lPc2d1DxZeopg2s5tokZ+X47tKrxulYoOh5bc=; b=he0ZjtVpwNxuukiPpZ9DyOH6EE+lsUEUJ707IspVm6XSZE+GAT2URF+X5JIFOfnMyE 4uPE9ut4qWztNMz2qbnCvSmGCqvIoHCAnAcam9GxfXs4JSLred384ewf6oChYjjUVB91 jC49AOKqfbr3PlKKJsQubcEKx+jgXdH8HP1X6g5ka1D1NqLpQ7p8qtfAScsgTesR8rpJ tvJiDz+NPBeZ/Dsn0pfsxgpMb0PM2f0Fh7auRuR6z/GrE2nBJCNe8ZFTJrCjcGtwEox/ AkKndLuk1HUdjk/vuQjT7RXmyaZeSmmpGpSO9crxp5xXH93Xj0tvZxKN258iaNfLFI73 UfQQ== X-Gm-Message-State: AGRZ1gKAAuUZ5BzxY8LLK9OjDy1FbvsOXBPwmO/XpWRlUNhfXoBTO3p+ z+3zAnQjGG8YDXmHOgy3mlEz/eX28ag= X-Google-Smtp-Source: AJdET5dNdoBdR32qdvkcwjhDwenWnhGlW0jOdE1N5bfCEAycaN4BrAZumvYCzeB6I9t5EPhssIzReQ== X-Received: by 2002:a24:6c8e:: with SMTP id w136-v6mr227856itb.153.1540563959416; Fri, 26 Oct 2018 07:25:59 -0700 (PDT) Received: from [192.168.1.56] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id k15-v6sm2172065itk.8.2018.10.26.07.25.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Oct 2018 07:25:58 -0700 (PDT) Subject: Re: [PATCH V4] block: fix the DISCARD request merge To: Jianchao Wang Cc: martin.petersen@oracle.com, tom.leiming@gmail.com, hch@lst.de, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <1540546116-1620-1-git-send-email-jianchao.w.wang@oracle.com> From: Jens Axboe Message-ID: <4ee51782-acbb-bcc9-6692-39e9b8df477f@kernel.dk> Date: Fri, 26 Oct 2018 08:25:56 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <1540546116-1620-1-git-send-email-jianchao.w.wang@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/26/18 3:28 AM, Jianchao Wang wrote: > There are two cases when handle DISCARD merge. > If max_discard_segments == 1, the bios/requests need to be contiguous > to merge. If max_discard_segments > 1, it takes every bio as a range > and different range needn't to be contiguous. > > But now, attempt_merge screws this up. It always consider contiguity > for DISCARD for the case max_discard_segments > 1 and cannot merge > contiguous DISCARD for the case max_discard_segments == 1, because > rq_attempt_discard_merge always returns false in this case. > This patch fixes both of the two cases above. Looks good to me, but: > diff --git a/block/blk-merge.c b/block/blk-merge.c > index 42a4674..cf817c7a 100644 > --- a/block/blk-merge.c > +++ b/block/blk-merge.c > @@ -714,6 +714,32 @@ static void blk_account_io_merge(struct request *req) > part_stat_unlock(); > } > } > +/* > + * Two cases of handling DISCARD merge: > + * If max_discard_segments > 1, the driver takes every bio > + * as a range and send them to controller together. The ranges > + * needn't to be contiguous. > + * Otherwise, the bios/requests will be handled as same as > + * others which should be contiguous. > + */ > +static inline bool blk_discard_mergable(struct request *req) > +{ > + if (req_op(req) == REQ_OP_DISCARD && > + queue_max_discard_segments(req->q) > 1) > + return true; > + else > + return false; > +} Please get rid of the redundant else. -- Jens Axboe