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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 3F291C00449 for ; Mon, 1 Oct 2018 23:20:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED87D2084C for ; Mon, 1 Oct 2018 23:20:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=virtuozzo.com header.i=@virtuozzo.com header.b="dxjwGiCX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED87D2084C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.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 S1726636AbeJBGBD (ORCPT ); Tue, 2 Oct 2018 02:01:03 -0400 Received: from mail-eopbgr40102.outbound.protection.outlook.com ([40.107.4.102]:17040 "EHLO EUR03-DB5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725936AbeJBGBC (ORCPT ); Tue, 2 Oct 2018 02:01:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=virtuozzo.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=j2KNZAm+OA0ZQXcWLA8BzV/hcebFUqEjBK3sBd4cZOo=; b=dxjwGiCXejJ8I3AyVCrj5YWxnS03ztPtSQmMapdGVSCA6tu0A6mqtNcFUQJuiDzbQPmRwcxR4V7QXtbgxVjNa4kGx0DZmJOhLyOtMftcCnugN9+NwR3WYzVMgzKH6gEuni+rUlXKiRWddmnYQgTgPWhoNbZGSwaZHxiSLwzX4Mw= Received: from AM6PR08MB3253.eurprd08.prod.outlook.com (52.135.164.146) by AM6PR08MB3525.eurprd08.prod.outlook.com (20.177.114.206) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1164.25; Mon, 1 Oct 2018 23:20:47 +0000 Received: from AM6PR08MB3253.eurprd08.prod.outlook.com ([fe80::a458:ca6c:fe4e:fc39]) by AM6PR08MB3253.eurprd08.prod.outlook.com ([fe80::a458:ca6c:fe4e:fc39%4]) with mapi id 15.20.1185.024; Mon, 1 Oct 2018 23:20:47 +0000 From: Andrey Vagin To: Thomas Gleixner CC: "Eric W. Biederman" , Dmitry Safonov , "linux-kernel@vger.kernel.org" , Dmitry Safonov <0x7f454c46@gmail.com>, Adrian Reber , Andy Lutomirski , Christian Brauner , Cyrill Gorcunov , "H. Peter Anvin" , Ingo Molnar , Jeff Dike , Oleg Nesterov , Pavel Emelianov , Shuah Khan , "containers@lists.linux-foundation.org" , "criu@openvz.org" , "linux-api@vger.kernel.org" , "x86@kernel.org" , Alexey Dobriyan , "linux-kselftest@vger.kernel.org" Subject: Re: [RFC 00/20] ns: Introduce Time Namespace Thread-Topic: [RFC 00/20] ns: Introduce Time Namespace Thread-Index: AQHUUFpuovisR+B/R0ChKHU4yyCZyaT6rFafgATOTICAAIlk1v//x8cAgAMSiTyAAdN9gIAAA0KAgAZk6gA= Date: Mon, 1 Oct 2018 23:20:47 +0000 Message-ID: <20181001232033.GA31324@outlook.office365.com> References: <20180919205037.9574-1-dima@arista.com> <874lej6nny.fsf@xmission.com> <20180924205119.GA14833@outlook.office365.com> <874leezh8n.fsf@xmission.com> <20180925014150.GA6302@outlook.office365.com> <87zhw4rwiq.fsf@xmission.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Mutt/1.10.0 (2018-05-17) x-originating-ip: [2620:0:1000:fd1f:f3f3:aec8:82f8:da4d] x-clientproxiedby: BYAPR07CA0013.namprd07.prod.outlook.com (2603:10b6:a02:bc::26) To AM6PR08MB3253.eurprd08.prod.outlook.com (2603:10a6:209:47::18) authentication-results: spf=none (sender IP is ) smtp.mailfrom=avagin@virtuozzo.com; x-ms-exchange-messagesentrepresentingtype: 1 x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;AM6PR08MB3525;20:IDGB2QNUGWnQOaoqD0JL4b7nun++UNsYiqnUqcIMNpAlppiQp1bnPcUlwQkK+mz001DMwg5MLpwL/AkXVF8rswcpx3HLRtOb3PW7lZecCHkxX6pkDznBrPbGdTP+chAGauJe+0E3/iI+cBsnrAyY1XVFS/ZP8C9WlnN8wS2QYy4= x-ms-office365-filtering-correlation-id: 5a94aac5-68e0-4c12-cac4-08d627f48498 x-microsoft-antispam: BCL:0;PCL:0;RULEID:(7020095)(4652040)(8989299)(4534165)(4627221)(201703031133081)(201702281549075)(8990200)(5600074)(711020)(2017052603328)(7153060)(7193020);SRVR:AM6PR08MB3525; x-ms-traffictypediagnostic: AM6PR08MB3525: x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:; x-ms-exchange-senderadcheck: 1 x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(6040522)(2401047)(8121501046)(5005006)(93006095)(93001095)(10201501046)(3231355)(944501410)(52105095)(3002001)(149066)(150057)(6041310)(20161123564045)(20161123558120)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123562045)(20161123560045)(201708071742011)(7699051);SRVR:AM6PR08MB3525;BCL:0;PCL:0;RULEID:;SRVR:AM6PR08MB3525; x-forefront-prvs: 0812095267 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(376002)(136003)(396003)(366004)(346002)(39850400004)(199004)(189003)(6506007)(76176011)(8936002)(99286004)(9686003)(316002)(52116002)(6512007)(229853002)(186003)(2906002)(7736002)(305945005)(5250100002)(106356001)(6436002)(105586002)(33896004)(81166006)(93886005)(386003)(33656002)(8676002)(81156014)(68736007)(6486002)(86362001)(446003)(476003)(102836004)(486006)(46003)(97736004)(53936002)(11346002)(54906003)(58126008)(6916009)(256004)(6246003)(71190400001)(39060400002)(71200400001)(5660300001)(14444005)(14454004)(1076002)(478600001)(6116002)(7416002)(25786009)(4326008)(2900100001)(18370500001);DIR:OUT;SFP:1102;SCL:1;SRVR:AM6PR08MB3525;H:AM6PR08MB3253.eurprd08.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; received-spf: None (protection.outlook.com: virtuozzo.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: 52yttdDprk08GiFXgBfp+Ya5PzNvp8ay3nJIYPazgiMooEyXlRQx5XS6aYVwCz0Q5MOzPIOPD1N8AiU5NwZZ4Zafw7Cu69veutQzcYy0RQcbJq3hjG/MPJjzQc+eT95V/1PJsesd6s1JEwCDm93lAG57G6XN8F3/fG4/PJbGkJ/0WiKOq5zDzkImFQvKn0fJkpzP+gO0/ABtSxS+QFZd/R4J2c2eDIzKxi65gQbrB1w56sdi5bVoqseI/QbuOM8ydNyWIegrJ6rGuSb82NJuIItD2XiKY4UVaQHM3mj+CbpGxhzbqHt18BDP1Dw6hURxpEfhnkGZgASRaHcVfp+c1v/iamVJyX6ZHgCWVP4Aiho= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="koi8-r" Content-ID: <8C46EDA933FB6941ACA5110F5EB9E607@eurprd08.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5a94aac5-68e0-4c12-cac4-08d627f48498 X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Oct 2018 23:20:47.4846 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM6PR08MB3525 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 27, 2018 at 11:41:49PM +0200, Thomas Gleixner wrote: > On Thu, 27 Sep 2018, Thomas Gleixner wrote: > > Add time skew via NTP/PTP into the picture and you might have to adjust > > timers as well, because you need to guarantee that they are not expirin= g > > early. > >=20 > > I haven't looked through Dimitry's patches yet, but I don't see how thi= s > > can work at all without introducing subtle issues all over the place. >=20 > And just a quick scan tells me that this is broken. Timers will expire > early or late. The latter is acceptible to some extent, but larger delays > might come with surprise. Expiring early is an absolute nono. Do you mean that we have to adjust all timers after changing offset for CLOCK_MONOTONIC or CLOCK_BOOTTIME? Our idea is that offsets for monotonic and boot times will be set immediately after creating a time namespace before using any timers. It is interesting to think what a use-case for changing these offsets after creating timers. It may be useful for testing needs. A user sets a timer in an hour and then change a clock offset forward and check that a test application handles the timer properly. >=20 > Thanks, >=20 > tglx >=20