Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755641AbbBLNBw (ORCPT ); Thu, 12 Feb 2015 08:01:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35136 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755204AbbBLNBu (ORCPT ); Thu, 12 Feb 2015 08:01:50 -0500 Date: Thu, 12 Feb 2015 07:01:21 -0600 From: Josh Poimboeuf To: Jiri Kosina Cc: Peter Zijlstra , Ingo Molnar , Masami Hiramatsu , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Seth Jennings , Vojtech Pavlik Subject: Re: [RFC PATCH 6/9] livepatch: create per-task consistency model Message-ID: <20150212130121.GC18578@treble.redhat.com> References: <2c3d1e685dae5cccc2dfdb1b24c241b2f1c89348.1423499826.git.jpoimboe@redhat.com> <20150212032121.GA18578@treble.redhat.com> <20150212115628.GL2896@worktop.programming.kicks-ass.net> <20150212123906.GC23367@worktop.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1368 Lines: 36 On Thu, Feb 12, 2015 at 01:42:01PM +0100, Jiri Kosina wrote: > On Thu, 12 Feb 2015, Peter Zijlstra wrote: > > > > Well, the fact indisputable fact is that there is a demand for this. It's > > > not about one machine, it's about scheduling dowtimes of datacentres. > > > > The changelog says: > > > > > ... A patch can remain in the > > > transition state indefinitely, if any of the tasks are stuck in the > > > previous universe. > > > > Therefore there is no scheduling anything. Without timeliness guarantees > > you can't make a schedule. > > > > Might as well just reboot, at least that's fairly well guaranteed to > > happen. > > All running (reasonably alive) tasks will be running patched code though. > > You can't just claim complete victory (and get ready for accepting another > patch, etc) if there is a long-time sleeper that hasn't been converted > yet. Agreed. And also we have several strategies for reducing the time needed to get all tasks to a patched state (see patch 9 of this series for more details). The goal is to not leave systems in limbo for more than a few seconds. -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/