From owner-freebsd-hackers@FreeBSD.ORG Mon Oct 20 14:59:33 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1F1D816A4B3 for ; Mon, 20 Oct 2003 14:59:33 -0700 (PDT) Received: from ebb.errno.com (ebb.errno.com [66.127.85.87]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4901143FB1 for ; Mon, 20 Oct 2003 14:59:32 -0700 (PDT) (envelope-from sam@errno.com) Received: from 66.127.85.91 ([66.127.85.91]) (authenticated bits=0) by ebb.errno.com (8.12.9/8.12.9) with ESMTP id h9KLxU0x091582 (version=TLSv1/SSLv3 cipher=RC4-MD5 bits=128 verify=NO); Mon, 20 Oct 2003 14:59:31 -0700 (PDT) (envelope-from sam@errno.com) From: Sam Leffler Organization: Errno Consulting To: Kip Macy , hackers@freebsd.org Date: Mon, 20 Oct 2003 15:00:52 -0700 User-Agent: KMail/1.5.3 References: <20031020134532.B63978@demos.bsdclusters.com> In-Reply-To: <20031020134532.B63978@demos.bsdclusters.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200310201500.53053.sam@errno.com> Subject: Re: process checkpoint restore facility now in DragonFly BSD X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Oct 2003 21:59:33 -0000 I've lived through several checkpointing implementations. You've got the easy part. Applications must participate or such a facility has very limited usefulness. Delivering a signal is only part of the problem; there tend to be issues synchronizing user-mode checkpoint of application state with the kernel's desired to stop the process and squirrel away state. There's lots of stuff published about this; check the literature. Sam