From owner-freebsd-stable@FreeBSD.ORG Wed Aug 10 13:21:51 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 170241065677 for ; Wed, 10 Aug 2011 13:21:51 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from qmta03.westchester.pa.mail.comcast.net (qmta03.westchester.pa.mail.comcast.net [76.96.62.32]) by mx1.freebsd.org (Postfix) with ESMTP id B53BC8FC16 for ; Wed, 10 Aug 2011 13:21:50 +0000 (UTC) Received: from omta23.westchester.pa.mail.comcast.net ([76.96.62.74]) by qmta03.westchester.pa.mail.comcast.net with comcast id JdH71h0091c6gX853dMqW0; Wed, 10 Aug 2011 13:21:50 +0000 Received: from koitsu.dyndns.org ([67.180.84.87]) by omta23.westchester.pa.mail.comcast.net with comcast id JdMp1h0041t3BNj3jdMqlC; Wed, 10 Aug 2011 13:21:50 +0000 Received: by icarus.home.lan (Postfix, from userid 1000) id 2F2F6102C19; Wed, 10 Aug 2011 06:21:48 -0700 (PDT) Date: Wed, 10 Aug 2011 06:21:48 -0700 From: Jeremy Chadwick To: Daniel Kalchev Message-ID: <20110810132148.GA37186@icarus.home.lan> References: <4E4143A6.6030307@digsys.bg> <20110809151646.GF1814@albert.catwhisker.org> <4E422F8A.1070508@digsys.bg> <20110810074759.GA30254@icarus.home.lan> <4E423CAC.20008@digsys.bg> <20110810084759.GA32346@icarus.home.lan> <4E426083.1020207@digsys.bg> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E426083.1020207@digsys.bg> User-Agent: Mutt/1.5.21 (2010-09-15) Cc: FreeBSD-STABLE Mailing List Subject: Re: 32GB limit per swap device? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Aug 2011 13:21:51 -0000 On Wed, Aug 10, 2011 at 01:42:11PM +0300, Daniel Kalchev wrote: > > > On 10.08.11 11:47, Jeremy Chadwick wrote: > >So we're back to where we started: swap slices/partitions can be > >greater than 32GBytes in size, but "something" is limiting the > >maximum amount of memory which can be dumped to a single swap swap > >to 32GBytes. > It seems there is still some confusion. Partition size(s) is 64GB, > but FreeBSD will use only 32GB of that for swap. > > Trying: > > sysctl debug.minidump=0 > sysctl debug.kdb.panic=1 > > Produces 64GB dump, but.. I can't see the dump on the swap device > (savecore doesn't find the magic number). My swap device is gmirror > or two slices (/dev/mirror/swap). > > Removing the gmirror and listing both slices for swap .. works. > > > I could use separate device for dumps, but the disk real estate on > this particular blade is limited... > > Well, I really asked two questions: > Q1: Is FreeBSD still limited to 32GB per swap slice? > A1: yes. There is limit set in /usr/src/sys/vm/swap_pager.c > > Q2: If FreeBSD will only use 32GB of the slice for swap, will it > dump larger (64GB in my case) core in there? > A2a: yes. > A2b: If the swap slice is gmirrored, you don't get any dump back. > > I believe the gmirror bug might exist in smaller partitions as well, > but haven't tested it yet (have few such systems that never duped > core). It does not matter if I do full dump or minidump: on > gmirrored 64GB partittion savecore does not find anything. Is this somehow related to the NOTES section of gmirror(1), which talks about caveats/problems with generating kernel dumps on gmirrored swap? It seems that as the more technical details of your system start to present themselves, the answers start to present themselves as well. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, US | | Making life hard for others since 1977. PGP 4BD6C0CB |