From owner-freebsd-current@FreeBSD.ORG Thu Apr 8 04:44:50 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D6CCF16A523; Thu, 8 Apr 2004 04:44:50 -0700 (PDT) Received: from mail017.syd.optusnet.com.au (mail017.syd.optusnet.com.au [211.29.132.168]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4A1D543D49; Thu, 8 Apr 2004 04:44:49 -0700 (PDT) (envelope-from peterjeremy@optushome.com.au) Received: from server.vk2pj.dyndns.org (c211-30-75-229.belrs2.nsw.optusnet.com.au [211.30.75.229]) i38BifA08946; Thu, 8 Apr 2004 21:44:47 +1000 Received: from server.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1])i38BifRu006800; Thu, 8 Apr 2004 21:44:41 +1000 (EST) (envelope-from peter@server.vk2pj.dyndns.org) Received: (from peter@localhost) by server.vk2pj.dyndns.org (8.12.10/8.12.10/Submit) id i38Bifao006799; Thu, 8 Apr 2004 21:44:41 +1000 (EST) (envelope-from peter) Date: Thu, 8 Apr 2004 21:44:41 +1000 From: Peter Jeremy To: Scott Long Message-ID: <20040408114441.GB6458@server.vk2pj.dyndns.org> References: <20040408091030.GA6458@server.vk2pj.dyndns.org> <40751A74.50504@freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <40751A74.50504@freebsd.org> User-Agent: Mutt/1.4.2.1i cc: Robert Watson cc: current@freebsd.org Subject: Re: panic on one cpu leaves others running... X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Apr 2004 11:44:51 -0000 On Thu, Apr 08, 2004 at 03:25:08AM -0600, Scott Long wrote: >Peter Jeremy wrote: >>On Thu, Apr 08, 2004 at 12:13:39AM -0400, Robert Watson wrote: >> >>>Funky, eh? I thought we used to have code to ipi the other cpu's and halt >>>them until the cpu in ddb was out agian. I guess I mis-remember, or that >>>code is broken... >> >> >>Look on it as a feature - most other Unices can't survive a panic. >>Being able to continue running in a degraded mode until a suitable >>maintenance window is available would be a real selling point in >>HA applications. Even being able to shutdown cleanly would be >>better than coming to a screaming halt. :-) (sort of). > >Not sure if you're joking or not here. I was joking about the FreeBSD behaviour (hence the smiley) but serious about the (potential) benefits of being able to degrade rather than die. > A panic usually means that >something unrecoverable happened, and that continuing on is not safe. I realise that. Hence actually being able to continue after a panic would be extremely difficult to do safely. (Probably not possible in general, though it might be in some special cases). Peter