From owner-freebsd-hackers@FreeBSD.ORG Mon Jun 26 18:14:17 2006 Return-Path: X-Original-To: freebsd-hackers@freebsd.org 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 6453916A4CC for ; Mon, 26 Jun 2006 18:14:17 +0000 (UTC) (envelope-from emaste@phaedrus.sandvine.ca) Received: from gw.sandvine.com (sandvine.com [199.243.201.138]) by mx1.FreeBSD.org (Postfix) with ESMTP id 67965466AB for ; Mon, 26 Jun 2006 18:12:55 +0000 (GMT) (envelope-from emaste@phaedrus.sandvine.ca) Received: from mailserver.sandvine.com ([192.168.1.10]) by gw.sandvine.com with Microsoft SMTPSVC(6.0.3790.1830); Mon, 26 Jun 2006 14:12:54 -0400 Received: from labgw2.phaedrus.sandvine.com ([192.168.3.11]) by mailserver.sandvine.com with Microsoft SMTPSVC(6.0.3790.1830); Mon, 26 Jun 2006 14:12:53 -0400 Received: by labgw2.phaedrus.sandvine.com (Postfix, from userid 12627) id 7F63611643; Mon, 26 Jun 2006 14:12:53 -0400 (EDT) Date: Mon, 26 Jun 2006 14:12:53 -0400 From: Ed Maste To: Mike Meyer Message-ID: <20060626181253.GA59701@sandvine.com> References: <449D8616.5040306@tamara-b.org> <17565.37706.966913.737964@bhuda.mired.org> <20060626111208.P77513@woozle.rinet.ru> <17567.60116.599544.571163@bhuda.mired.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <17567.60116.599544.571163@bhuda.mired.org> User-Agent: Mutt/1.4.2.1i X-OriginalArrivalTime: 26 Jun 2006 18:12:53.0721 (UTC) FILETIME=[24990490:01C6994C] Cc: freebsd-hackers@freebsd.org, Dmitry Morozovsky , bob@tamara-b.org Subject: Re: A New FreeBSD Server X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Jun 2006 18:14:17 -0000 On Mon, Jun 26, 2006 at 10:10:28AM -0400, Mike Meyer wrote: > In <20060626111208.P77513@woozle.rinet.ru>, Dmitry Morozovsky typed: > > On Sat, 24 Jun 2006, Mike Meyer wrote: > > MM> The other constraint on swap is that if you want the system to save a > > MM> core dump if it panics, you need a device to dump on that's 64Kb > > MM> bigger than ram. That's one device, not all of swap. > > This is not quite true, as there always are some unused memory regions, hence > > you need not add 64k to RAM size. At least, I had no trouble using swap == RAM > > for last 5 years or so... > > Or memory areas that aren't needed when doing the post mortem. The > question is, how do you guarantee that those are what's not going to > make it out to the dump device? The core dump routine won't even attempt to write if the swap space is too small, so there's no ambiguity as to what makes it into the core file. FreeBSD 5.x and previous try to write all of memory out so the extra 64Kb or so is necessary. Also, -CURRENT uses "minidumps" on i386 and amd64, so only memory regions of use are written out and you can get by with swap smaller than RAM. -ed