From owner-freebsd-stable@FreeBSD.ORG Wed Aug 10 08:48:02 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 A15131065676 for ; Wed, 10 Aug 2011 08:48:02 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from qmta13.westchester.pa.mail.comcast.net (qmta13.westchester.pa.mail.comcast.net [76.96.59.243]) by mx1.freebsd.org (Postfix) with ESMTP id 4108F8FC12 for ; Wed, 10 Aug 2011 08:48:01 +0000 (UTC) Received: from omta19.westchester.pa.mail.comcast.net ([76.96.62.98]) by qmta13.westchester.pa.mail.comcast.net with comcast id JYkP1h00227AodY5DYo2xZ; Wed, 10 Aug 2011 08:48:02 +0000 Received: from koitsu.dyndns.org ([67.180.84.87]) by omta19.westchester.pa.mail.comcast.net with comcast id JYo01h00S1t3BNj3fYo1rm; Wed, 10 Aug 2011 08:48:02 +0000 Received: by icarus.home.lan (Postfix, from userid 1000) id 6E493102C19; Wed, 10 Aug 2011 01:47:59 -0700 (PDT) Date: Wed, 10 Aug 2011 01:47:59 -0700 From: Jeremy Chadwick To: Holger Kipp Message-ID: <20110810084759.GA32346@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Cc: FreeBSD-STABLE Mailing List , Daniel Kalchev 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 08:48:02 -0000 On Wed, Aug 10, 2011 at 08:27:27AM +0000, Holger Kipp wrote: > > Am 10.08.2011 um 10:09 schrieb Daniel Kalchev: > > > On 10.08.11 10:47, Jeremy Chadwick wrote: > >> On Wed, Aug 10, 2011 at 10:13:14AM +0300, Daniel Kalchev wrote: > >>> I am more concerned that with 32GB of swap in single device I could not dump kernel core, with 64GB of RAM. > >> My apologies if I've misunderstood something, but why does this of any > >> concern? Machine has 64GB RAM. You have a single swap slice that's > >> effectively 32GB. How is a kernel panic worth of 64GB RAM going to fit > >> into a 32GB swap slice? > >> > > The swap partitions are 64GB, it is only that FreeBSD refuses to use more than 32GB of each for swap. But.. it might happily dump core to the whole partition, tests will show. > > I doubt it. Have you tried increasing kern.maxswzone? It is the size in KB (for 32GB it is set to 33554432). > kern.maxswzone: Maximum memory for swap metadata The variable is set to 32MBytes, not 32GBytes. The default size is defined as variable VM_SWZONE_SIZE_MAX, which is 32*1024*1024 per sys/i386/include/param.h and sys/amd64/include/param.h. Furthermore, this variable does not do what you're implying. It's used within swap_pager_swap_init() in sys/vm/swap_pager.c, which is what's used for initialising a process that's being paged out (swapped out). That doesn't appear to have anything to do with actual memory dumps. 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. -- | 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 |