From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751495AbdJDBED (ORCPT ); Tue, 3 Oct 2017 21:04:03 -0400 Received: from esa4.hgst.iphmx.com ([216.71.154.42]:32214 "EHLO esa4.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751117AbdJDBD7 (ORCPT ); Tue, 3 Oct 2017 21:03:59 -0400 X-IronPort-AV: E=Sophos;i="5.42,475,1500912000"; d="scan'208";a="55924343" From: Bart Van Assche To: "rjw@rjwysocki.net" , "mcgrof@kernel.org" CC: "boris.ostrovsky@oracle.com" , "ONeukum@suse.com" , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "nborisov@suse.com" , "oleg.b.antonyan@gmail.com" , "linux-pm@vger.kernel.org" , "linux-xfs@vger.kernel.org" , "pavel@ucw.cz" , "darrick.wong@oracle.com" , "viro@zeniv.linux.org.uk" , "ming.lei@redhat.com" , "jgross@suse.com" , "oleksandr@natalenko.name" , "todd.e.brandt@linux.intel.com" , "martin.petersen@oracle.com" , "linux-fsdevel@vger.kernel.org" , "jikos@kernel.org" , "len.brown@intel.com" , "tytso@mit.edu" , "jack@suse.cz" Subject: Re: [RFC 5/5] pm: remove kernel thread freezing Thread-Topic: [RFC 5/5] pm: remove kernel thread freezing Thread-Index: AQHTPHjmObYS0BO+2Eu+Ihz8qcgUbKLSemYAgAAmCICAADt2AIAABHSA Date: Wed, 4 Oct 2017 01:03:54 +0000 Message-ID: <1507079033.3075.3.camel@wdc.com> References: <20171003185313.1017-1-mcgrof@kernel.org> <20171003185313.1017-6-mcgrof@kernel.org> <1862632.MOTT9GD8nq@aspire.rjw.lan> <29004244.0jnB6Wc1z6@aspire.rjw.lan> <20171004004756.GN2294@wotan.suse.de> In-Reply-To: <20171004004756.GN2294@wotan.suse.de> 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: [73.223.62.206] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;CY1PR0401MB1535;20:k9Adblhl4U7WXsc7of5tXn4vfLxVhtA+FssZMGxu2hTd5rQcu195YmYQGv4kI8vkbgr7BkhEy1jWzP/lniTe/MIOec36Nz2Fsk02fA2f4wjUCl0+bbuBH4dXwfPteC+VQxxxr12gnNIl7UfrCpP3mta+TLKvqLC/X/SmqJZ8ZUU= x-ms-office365-filtering-correlation-id: 3a104357-c0c9-434f-faed-08d50ac3c8be x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(2017030254152)(48565401081)(2017052603199)(201703131423075)(201703031133081)(201702281549075);SRVR:CY1PR0401MB1535; x-ms-traffictypediagnostic: CY1PR0401MB1535: wdcipoutbound: EOP-TRUE x-exchange-antispam-report-test: UriScan:; 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)(100000703101)(100105400095)(10201501046)(93006095)(93001095)(3002001)(6055026)(6041248)(201703131423075)(201702281528075)(201703061421075)(201703061406153)(20161123558100)(20161123560025)(20161123562025)(20161123555025)(20161123564025)(6072148)(201708071742011)(100000704101)(100105200095)(100000705101)(100105500095);SRVR:CY1PR0401MB1535;BCL:0;PCL:0;RULEID:(100000800101)(100110000095)(100000801101)(100110300095)(100000802101)(100110100095)(100000803101)(100110400095)(100000804101)(100110200095)(100000805101)(100110500095);SRVR:CY1PR0401MB1535; x-forefront-prvs: 0450A714CB x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(346002)(39860400002)(376002)(189002)(377424004)(24454002)(199003)(5660300001)(103116003)(4326008)(3280700002)(8936002)(66066001)(33646002)(77096006)(305945005)(2906002)(2950100002)(8676002)(3660700001)(81156014)(68736007)(7736002)(81166006)(106356001)(6486002)(229853002)(86362001)(6246003)(6436002)(25786009)(105586002)(6506006)(7416002)(53936002)(93886005)(316002)(39060400002)(76176999)(97736004)(36756003)(99286003)(110136005)(54906003)(101416001)(2501003)(6116002)(102836003)(189998001)(478600001)(54356999)(2900100001)(3846002)(14454004)(6512007)(72206003)(50986999);DIR:OUT;SFP:1102;SCL:1;SRVR:CY1PR0401MB1535;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: MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-originalarrivaltime: 04 Oct 2017 01:03:54.3777 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY1PR0401MB1535 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 v94149sh007593 On Wed, 2017-10-04 at 02:47 +0200, Luis R. Rodriguez wrote: > 3) Lookup for kthreads which seem to generate IO -- address / review if > removal of the freezer API can be done somehow with a quescing. This > is currently for example being done on SCSI / md. > 4) Only after all the above is done should we consider this patch or some > form of it. After having given this more thought, I think we should omit these last two steps. Modifying the md driver such that it does not submit I/O requests while processes are frozen requires either to use the freezer API or to open-code it. I think there is general agreement in the kernel community that open-coding a single mechanism in multiple drivers is wrong. Does this mean that instead of removing the freezer API we should keep it and review all its users instead? Bart.