From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755813AbcLTDzw (ORCPT ); Mon, 19 Dec 2016 22:55:52 -0500 Received: from mail-sn1nam01on0139.outbound.protection.outlook.com ([104.47.32.139]:11336 "EHLO NAM01-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751583AbcLTDzu (ORCPT ); Mon, 19 Dec 2016 22:55:50 -0500 From: Dexuan Cui To: Jens Axboe , Ming Lei CC: Linux Kernel Mailing List , linux-block , Christoph Hellwig , "Vitaly Kuznetsov" , Keith Busch , "Hannes Reinecke" , Mike Christie , "Martin K. Petersen" , Toshi Kani , "Dan Williams" , Damien Le Moal Subject: RE: [PATCH] block: loose check on sg gap Thread-Topic: [PATCH] block: loose check on sg gap Thread-Index: AQHSWmkhxoiFMjA3YU+owCb8wxj9kqEQLFOg Date: Tue, 20 Dec 2016 03:41:03 +0000 Message-ID: References: <1481971751-4016-1-git-send-email-ming.lei@canonical.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=decui@microsoft.com; x-originating-ip: [2404:f801:9000:18::90] x-ms-office365-filtering-correlation-id: 34b68b35-f7fa-4eef-6c74-08d4288a05f9 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001);SRVR:MWHPR03MB2669; x-microsoft-exchange-diagnostics: 1;MWHPR03MB2669;7:NJMyhr12KmNQ80rPjcpZJhZf4N9i9zAIpBLpZdqn1FktRlYE3QIejjDOi3Qb1kHeK4sWaKB9bJMRtlqhbny6b8Coz8QmiyIo98rXjAJaW3C1KXwgFm84qpX3/VBQE2ULDDmqWH0U12BXbOrqZ2U5x/1iR6LZJN/Aa7QkCqellBV6AgS6ttHnTviGsfdr1H6ff6lRqEGBSxRr69A3jqAuSmXQ3ijvIaF5Nl/wj89cc3Pzgw/l5AKtypXprrSR832OxcJCJ5FoXVlmepEkXEFEpsMuAqHMV3do67NAWDvvv7gUy7kqtOgL6kGK+RvbfA9X2k/tHUoJdMuftQjrM+LAYPkBzhKpVoGiRSfx9Q/HxjaF8IV2hgrcyeGNe72d/DRf4ls8iutDirwTxpPk8KeVZG+uh/LzHsnfAqN6je2i03VKOXkem/vugsJu+bmim5Fhm2wwU2F6zcGz2n+tIUswYqHwHebLusXstZewqykbAHk= x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(79135771888625)(227479698468861)(9452136761055)(67672495146484)(146099531331640)(198206253151910)(228905959029699); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(61425038)(6040375)(601004)(2401047)(5005006)(8121501046)(10201501046)(3002001)(6055026)(61426038)(61427038)(6041248)(20161123564025)(20161123562025)(20161123555025)(20161123560025)(6072148)(6047074);SRVR:MWHPR03MB2669;BCL:0;PCL:0;RULEID:;SRVR:MWHPR03MB2669; x-forefront-prvs: 0162ACCC24 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(7916002)(39860400002)(39410400002)(39840400002)(39450400003)(39850400002)(199003)(24454002)(377454003)(189002)(77096006)(106116001)(50986999)(33656002)(8676002)(97736004)(106356001)(2900100001)(54356999)(76176999)(189998001)(105586002)(7416002)(122556002)(5005710100001)(99286002)(8936002)(76576001)(74316002)(9686002)(38730400001)(7736002)(229853002)(92566002)(81166006)(68736007)(10090500001)(81156014)(6506006)(101416001)(6116002)(4326007)(305945005)(102836003)(5001770100001)(3660700001)(3280700002)(8990500004)(2950100002)(6436002)(5660300001)(10290500002)(2906002)(86612001)(86362001)(7696004)(93886004)(25786008);DIR:OUT;SFP:1102;SCL:1;SRVR:MWHPR03MB2669;H:MWHPR03MB2669.namprd03.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Dec 2016 03:41:03.5061 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR03MB2669 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id uBK3txgm022512 > From: Jens Axboe [mailto:axboe@fb.com] > Sent: Tuesday, December 20, 2016 10:31 > To: Ming Lei > Cc: Linux Kernel Mailing List ; linux-block block@vger.kernel.org>; Christoph Hellwig ; Dexuan Cui > ; Vitaly Kuznetsov ; Keith Busch > ; Hannes Reinecke ; Mike Christie > ; Martin K. Petersen ; > Toshi Kani ; Dan Williams ; > Damien Le Moal > Subject: Re: [PATCH] block: loose check on sg gap > > On 12/19/2016 07:07 PM, Ming Lei wrote: > > On Sun, Dec 18, 2016 at 12:49 AM, Jens Axboe wrote: > >> On 12/17/2016 03:49 AM, Ming Lei wrote: > >>> If the last bvec of the 1st bio and the 1st bvec of the next > >>> bio are contineous physically, and the latter can be merged > >>> to last segment of the 1st bio, we should think they don't > >>> violate sg gap(or virt boundary) limit. > >>> > >>> Both Vitaly and Dexuan reported lots of unmergeable small bios > >>> are observed when running mkfs on Hyper-V virtual storage, and > >>> performance becomes quite low, so this patch is figured out for > >>> fixing the performance issue. > >>> > >>> The same issue should exist on NVMe too sine it sets virt boundary too. > >> > >> It looks pretty reasonable to me. I'll queue it up for some testing, > >> changes like this always make me a little nervous. > > > > Understood. > > > > But given it is still in early stage of 4.10 cycle, seems fine to expose > > it now, and we should have enough time to fix it if there might be > > regressions. > > > > BTW, it passes my xfstest(ext4) over sata/NVMe. > > It's been fine here in testing, too. I'm not worried about performance > regressions, those we can always fix. Merging makes me worried about > corruption, and those regressions are much worse. > > Any reason we need to rush this? I'd be more comfortable pushing this to > 4.11, unless there are strong reasons this should make 4.10. > > -- > Jens Axboe Hi Jens, As far as I know, the patch is important to popular Linux distros, e.g. at least Ubuntu 14.04.5, 16.x and RHEL 7.3, when they run on Hyper-V/Azure, because they can suffer from a pretty bad throughput/latency in some cases, e.g. mkfs.ext4 for a 100GB partition can take 8 minutes, but with the patch, it only takes 1 second. Thanks, -- Dexuan