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=-4.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 8851EC46475 for ; Sat, 27 Oct 2018 11:46:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42D0C2086B for ; Sat, 27 Oct 2018 11:46:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="uOe9VH2k" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42D0C2086B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.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 S1728592AbeJ0U05 (ORCPT ); Sat, 27 Oct 2018 16:26:57 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:38386 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727723AbeJ0U05 (ORCPT ); Sat, 27 Oct 2018 16:26:57 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w9RBiuJV132075; Sat, 27 Oct 2018 11:46:09 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=UiiXUP4URBAv1LWDWA1H4hwlzq453peTTSNMGzdho3I=; b=uOe9VH2keplaQNl88Gmqc6gVdfaf12EJ03tRslgLnMhQmIS5lS2h+tIyV0zXBOu+HD01 X093Ey7d76171ljce5vkDtgvyRSMO57HuOCc0qrVT5iYS2bfxzikdgr2imNFx3XptSz8 JTU/hd4rBUvqb+XF3HLiYRO6+9uIe2pjJd4PiIcZftLO9wFasW3GCcGuFhdt/MHcyv+N KQkQ8gA92JBBf46qAseTh8/WNcq/tlu+Qe9C543egLdr6oLPm/pO+/H6kMUf6mA6/v6T 1M8Toq3FeyVXGYiy9pwGZybimab/0ZvKLM2WkMJJlh03a/8qzyD9k9K7Gn4MtQSZz3pb YQ== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp2120.oracle.com with ESMTP id 2ncgnqgm94-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 27 Oct 2018 11:46:09 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w9RBk88g020054 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 27 Oct 2018 11:46:08 GMT Received: from abhmp0019.oracle.com (abhmp0019.oracle.com [141.146.116.25]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w9RBk6j0006338; Sat, 27 Oct 2018 11:46:07 GMT Received: from [10.191.16.102] (/10.191.16.102) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 27 Oct 2018 04:46:06 -0700 Subject: Re: [PATCH V4] block: fix the DISCARD request merge To: Jens Axboe 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> <4ee51782-acbb-bcc9-6692-39e9b8df477f@kernel.dk> From: "jianchao.wang" Message-ID: <303b4275-d310-d27a-2b92-cdd25e76cffe@oracle.com> Date: Sat, 27 Oct 2018 19:46:10 +0800 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: <4ee51782-acbb-bcc9-6692-39e9b8df477f@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9058 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810270110 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jens On 10/26/18 10:25 PM, Jens Axboe wrote: > 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. > OK, I will change it and post next version. Thanks Jianchao