Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932333AbbBLMZS (ORCPT ); Thu, 12 Feb 2015 07:25:18 -0500 Received: from cantor2.suse.de ([195.135.220.15]:59130 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932216AbbBLMZR (ORCPT ); Thu, 12 Feb 2015 07:25:17 -0500 Date: Thu, 12 Feb 2015 13:25:14 +0100 (CET) From: Jiri Kosina To: Peter Zijlstra cc: Josh Poimboeuf , 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 In-Reply-To: <20150212115628.GL2896@worktop.programming.kicks-ass.net> Message-ID: References: <2c3d1e685dae5cccc2dfdb1b24c241b2f1c89348.1423499826.git.jpoimboe@redhat.com> <20150212032121.GA18578@treble.redhat.com> <20150212115628.GL2896@worktop.programming.kicks-ass.net> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1172 Lines: 31 On Thu, 12 Feb 2015, Peter Zijlstra wrote: > Its not at all clear how all this would work to me. And I'm not > motivated enough to go try and reverse engineer your patch; IMO > livepatching is utter fail. > > If your infrastructure relies on the uptime of a single machine you've > lost already. 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. But if this needs to be discussed, it should be done outside of this thread I guess. > FWIW, the barriers in klp_update_task_universe() and > klp_set_universe_goal() look like complete crack, and their comments are > seriously deficient. These particular barriers seem correct to me; you basically need to make sure that whenever a thread with TIF_KLP_NEED_UPDATE goes through do_notify_resume(), it sees proper universe number to be converted to. -- Jiri Kosina SUSE Labs -- 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/