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=-1.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS 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 5A6A9C43610 for ; Wed, 14 Nov 2018 09:23:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21113223DD for ; Wed, 14 Nov 2018 09:23:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="h76ljEgK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 21113223DD 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 S1732645AbeKNT0G (ORCPT ); Wed, 14 Nov 2018 14:26:06 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:41628 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727154AbeKNT0G (ORCPT ); Wed, 14 Nov 2018 14:26:06 -0500 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 wAE9JIuk112351; Wed, 14 Nov 2018 09:23:38 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=IK33j/cjJDM6Bqqq1sMY/uKXJH5fF4J2KBtaga5auPg=; b=h76ljEgKi7CBlQ1SqC01szZskUICsN0WJyI1cNThU9dDsY8qmkSQ8fVLpZPFPk2n4JIJ KWJ7rc168vMhAPXjs0HdC+tlvU41UdQr458J/IA14MFNFxo74uIo1b+0N4O26FRLkfvB EPJ+llF+YwNRs2OJAKWtvQrT3wTSqCpsX4yHSX5O1AUIteFIICyRvDbJtdOTZzegdVnn rdmNOch1QvijqctRBtZGGlnomocImsqYkgg8vSqpXfl9oD9r0a+Z5clwUoY2kioB4Tf7 E9zqp15/R5Dn3eo2rqWm4YxElebYqSEUxRLFbHue+BbSa2iA6R8ih2OxV/CJfKT6FjAm oA== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2120.oracle.com with ESMTP id 2nr7cs23ya-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 14 Nov 2018 09:23:37 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id wAE9NawZ017938 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 14 Nov 2018 09:23:37 GMT Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id wAE9NakT019453; Wed, 14 Nov 2018 09:23:36 GMT Received: from [10.182.71.8] (/10.182.71.8) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 14 Nov 2018 01:23:36 -0800 Subject: Re: [PATCH V7 1/4] blk-mq: refactor the code of issue request directly To: Ming Lei Cc: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <1542185131-15029-1-git-send-email-jianchao.w.wang@oracle.com> <1542185131-15029-2-git-send-email-jianchao.w.wang@oracle.com> <20181114091153.GB20550@ming.t460p> From: "jianchao.wang" Message-ID: <17b51550-d45b-9861-b172-74ee0e256d98@oracle.com> Date: Wed, 14 Nov 2018 17:23:48 +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: <20181114091153.GB20550@ming.t460p> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9076 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=897 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1811140086 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ming On 11/14/18 5:11 PM, Ming Lei wrote: >> >> - if (!blk_mq_get_dispatch_budget(hctx)) >> - goto insert; >> + if (unlikely(!blk_mq_get_dispatch_budget(hctx))) >> + goto out_unlock; > The unlikely annotation is a bit misleading, since out-of-budget can > happen frequently in case of low queue depth, and there are lots of > such examples. > This could be good for the case for no .get_budget and getting budget success. In case of out-of-budget, we insert the request which is slow path. It should be OK. Maybe some comment should be added for this. Thanks Jianchao