From owner-freebsd-hackers@FreeBSD.ORG  Wed Feb 15 05:41:11 2012
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 4DE99106564A
	for <freebsd-hackers@freebsd.org>; Wed, 15 Feb 2012 05:41:11 +0000 (UTC)
	(envelope-from julian@freebsd.org)
Received: from vps1.elischer.org (vps1.elischer.org [204.109.63.16])
	by mx1.freebsd.org (Postfix) with ESMTP id 1B27F8FC0A
	for <freebsd-hackers@freebsd.org>; Wed, 15 Feb 2012 05:41:10 +0000 (UTC)
Received: from julian-mac.elischer.org (c-67-180-24-15.hsd1.ca.comcast.net
	[67.180.24.15]) (authenticated bits=0)
	by vps1.elischer.org (8.14.4/8.14.4) with ESMTP id q1F5f7YT001256
	(version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO);
	Tue, 14 Feb 2012 21:41:10 -0800 (PST)
	(envelope-from julian@freebsd.org)
Message-ID: <4F3B45CD.7030904@freebsd.org>
Date: Tue, 14 Feb 2012 21:42:37 -0800
From: Julian Elischer <julian@freebsd.org>
User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US;
	rv:1.9.2.26) Gecko/20120129 Thunderbird/3.1.18
MIME-Version: 1.0
To: Jan Mikkelsen <janm-freebsd-hackers@transactionware.com>
References: <CAC46K3mc=V=oBOQnvEp9iMTyNXKD1Ki_+D0Akm8PM7rdJwDF8g@mail.gmail.com>
	<4F3A9266.9050905@freebsd.org>
	<D2890B34-AA3E-4495-8B9F-066153BFD0CF@transactionware.com>
In-Reply-To: <D2890B34-AA3E-4495-8B9F-066153BFD0CF@transactionware.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Maninya M <maninya@gmail.com>, freebsd-hackers@freebsd.org
Subject: Re: OS support for fault tolerance
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 15 Feb 2012 05:41:11 -0000

On 2/14/12 3:51 PM, Jan Mikkelsen wrote:
>
> Coming back to the multicore issue:
>
> The problem when a core fails is that it has affected more than its own state. It will be holding locks on shared resources and may have corrupted shared memory or asked a device to do the wrong thing. By the time you detect a fault in a core, it is too late. Checkpointing to main memory means that you need to be able to roll back to a checkpoint, and replay operations you know about. That involves more that CPU core state, that includes process file and device state.
>
I think that/s more or less what I was saying but with more concrete 
examples.
and yes I rememebr the tandem boxes from computer shows in Perth and 
Sydney, but never saw one in the field.