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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 49A3FC43382 for ; Thu, 27 Sep 2018 21:42:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F733216FE for ; Thu, 27 Sep 2018 21:42:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F733216FE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de 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 S1726473AbeI1ECi (ORCPT ); Fri, 28 Sep 2018 00:02:38 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:53121 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725727AbeI1ECi (ORCPT ); Fri, 28 Sep 2018 00:02:38 -0400 Received: from p5492e4c1.dip0.t-ipconnect.de ([84.146.228.193] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1g5e2g-0003f5-4D; Thu, 27 Sep 2018 23:41:50 +0200 Date: Thu, 27 Sep 2018 23:41:49 +0200 (CEST) From: Thomas Gleixner To: "Eric W. Biederman" cc: Andrey Vagin , 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 In-Reply-To: Message-ID: 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> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 expiring > early. > > I haven't looked through Dimitry's patches yet, but I don't see how this > can work at all without introducing subtle issues all over the place. 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. Thanks, tglx