From owner-freebsd-amd64@FreeBSD.ORG Fri May 28 16:49:44 2010 Return-Path: Delivered-To: amd64@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1E040106564A; Fri, 28 May 2010 16:49:44 +0000 (UTC) (envelope-from avg@icyb.net.ua) Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id 2D4468FC1C; Fri, 28 May 2010 16:49:42 +0000 (UTC) Received: from odyssey.starpoint.kiev.ua (alpha-e.starpoint.kiev.ua [212.40.38.101]) by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id TAA15166; Fri, 28 May 2010 19:49:27 +0300 (EEST) (envelope-from avg@icyb.net.ua) Message-ID: <4BFFF416.1080901@icyb.net.ua> Date: Fri, 28 May 2010 19:49:26 +0300 From: Andriy Gapon User-Agent: Thunderbird 2.0.0.24 (X11/20100517) MIME-Version: 1.0 To: Jeremy Chadwick References: <060401cafe37$a411b240$ec3516c0$@net> <4BFF894F.4010008@icyb.net.ua> <20100528134549.GA75411@icarus.home.lan> In-Reply-To: <20100528134549.GA75411@icarus.home.lan> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Tue, 01 Jun 2010 06:03:06 +0000 Cc: amd64@freebsd.org, freebsd-fs@freebsd.org Subject: Re: FreeBSD 8.1-Prerelease Panic amd64 w/ZFS.. X-BeenThere: freebsd-amd64@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Porting FreeBSD to the AMD64 platform List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 May 2010 16:49:44 -0000 on 28/05/2010 16:45 Jeremy Chadwick said the following: > It is? On amd64, vm.kmem_size (not vm.kmem_size_max) is what has to be > increased. I can point folks to the "official" statement from pjd@ and > some others if need be. For a very long time I questioned this because > for an even longer amount of time we were being told to increase > vm.kmem_size_max. > > vm.kmem_size_max, by default, is already huge on amd64 (~320GB or > something like that). Proof: > > vm.kmem_size_max: 329853485875 > > To the OP: you will need to increase vm.kmem_size in /boot/loader.conf > and reboot the system. "What value do I pick?" With 4GB, I would > recommend you use these two variables: > > vm.kmem_size="2048M" > vfs.zfs.arc_max="1536M" > > This will increase the available kmem, and also limit the ARC size > explicitly to nothing larger than 1.5GB. This should stabilise your > system. > Jeremy, you are correct, I was confused about what kmem_size_max and kmem_size meant. kmem_size_max is what could be available, in principle, for kmem_map. But in practice kmem_map size is auto-set to about 1/3 of physical memory available, this is on amd64. BTW, the "6GB" change you mentioned in your other email was more relevant to kmem_size_max, it was overridden since then with 512GB change. kmem size calculations are very well explained here: http://www.mailinglistarchive.com/freebsd-current@freebsd.org/msg10986.html BTW, I don't see why we set kmem size to a fraction of physical memory on amd64 where we have plenty of KVM available. I don't buy the argument that larger kmem size would allow kernel to exhaust all physical memory which would lead to a "bad thing", e.g. a panic - right now kernel can exhaust all kmem which does lead to a panic. Perhaps, default value of VM_KMEM_SIZE_SCALE should be change to one on amd64? -- Andriy Gapon