From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751932AbdJTUFe (ORCPT ); Fri, 20 Oct 2017 16:05:34 -0400 Received: from esa2.hgst.iphmx.com ([68.232.143.124]:19551 "EHLO esa2.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751404AbdJTUFc (ORCPT ); Fri, 20 Oct 2017 16:05:32 -0400 X-IronPort-AV: E=Sophos;i="5.43,408,1503331200"; d="scan'208";a="155051492" From: Bart Van Assche To: "roman.penyaev@profitbricks.com" CC: "hch@lst.de" , "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "hare@suse.com" , "axboe@fb.com" Subject: Re: [PATCH 1/1] [RFC] blk-mq: fix queue stalling on shared hctx restart Thread-Topic: [PATCH 1/1] [RFC] blk-mq: fix queue stalling on shared hctx restart Thread-Index: AQHTR/sENmxK85jYyU6rqB1jXfMKp6LrdKyAgAEJ/gCAAK7tgA== Date: Fri, 20 Oct 2017 20:05:30 +0000 Message-ID: <1508529929.3029.20.camel@wdc.com> References: <20171018102206.26020-1-roman.penyaev@profitbricks.com> <1508435243.2429.42.camel@wdc.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=Bart.VanAssche@wdc.com; x-originating-ip: [63.163.107.100] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;CY1PR0401MB1536;20:er1hVtkCLZ3psGbclM073NDd5Ydv6lndvO+Z9Ci1EJtjVdbPfbQXOhUv1g/Z2kT3UvedEO9+5Tkh9xk5+hbV+gYGl8m4t0PwaG62opaXP2DTsgcx8Qc3zMN0gQAOJBZ2ymAgKmaDo5TvOjhq7M2tnelmTBco72AwcOq/IL5oSOg= x-ms-exchange-antispam-srfa-diagnostics: SSOS; x-ms-office365-filtering-correlation-id: 94c82023-9b1f-4d29-587c-08d517f5ea15 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(48565401081)(4534020)(4602075)(4627075)(201703031133081)(201702281549075)(2017052603199);SRVR:CY1PR0401MB1536; x-ms-traffictypediagnostic: CY1PR0401MB1536: wdcipoutbound: EOP-TRUE x-exchange-antispam-report-test: UriScan:(17755550239193); x-microsoft-antispam-prvs: x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(100000700101)(100105000095)(100000701101)(100105300095)(100000702101)(100105100095)(6040450)(2401047)(5005006)(8121501046)(10201501046)(3231020)(100000703101)(100105400095)(93006095)(93001095)(3002001)(6055026)(6041248)(201703131423075)(201702281528075)(201703061421075)(201703061406153)(20161123560025)(20161123562025)(20161123564025)(20161123555025)(20161123558100)(6072148)(201708071742011)(100000704101)(100105200095)(100000705101)(100105500095);SRVR:CY1PR0401MB1536;BCL:0;PCL:0;RULEID:(100000800101)(100110000095)(100000801101)(100110300095)(100000802101)(100110100095)(100000803101)(100110400095)(100000804101)(100110200095)(100000805101)(100110500095);SRVR:CY1PR0401MB1536; x-forefront-prvs: 0466CA5A45 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(376002)(346002)(189002)(377424004)(24454002)(199003)(86362001)(36756003)(6916009)(2950100002)(575784001)(97736004)(105586002)(6506006)(5660300001)(106356001)(14454004)(103116003)(3846002)(72206003)(102836003)(4326008)(229853002)(316002)(6116002)(4001150100001)(2501003)(305945005)(2906002)(7736002)(76176999)(54356999)(50986999)(25786009)(68736007)(8936002)(2351001)(81156014)(6486002)(6436002)(33646002)(101416001)(66066001)(81166006)(77096006)(5640700003)(53936002)(3280700002)(478600001)(8676002)(6512007)(3660700001)(6246003)(99286003)(189998001)(54906003)(2900100001);DIR:OUT;SFP:1102;SCL:1;SRVR:CY1PR0401MB1536;H:CY1PR0401MB1536.namprd04.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: <8D3F4F40DB88F24E95EC4A761FBF4C0D@namprd04.prod.outlook.com> MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Oct 2017 20:05:30.3080 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY1PR0401MB1536 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 nfs id v9KK5cPU002159 On Fri, 2017-10-20 at 11:39 +0200, Roman Penyaev wrote: > But what bothers me is these looong loops inside blk_mq_sched_restart(), > and since you are the author of the original 6d8c6c0f97ad ("blk-mq: Restart > a single queue if tag sets are shared") I want to ask what was the original > problem which you attempted to fix? Likely I am missing some test scenario > which would be great to know about. Long loops? How many queues share the same tag set on your setup? How many hardware queues does your block driver create per request queue? Commit 6d8c6c0f97ad is something I came up with to fix queue lockups in the SCSI and dm-mq drivers. Bart.