From owner-freebsd-fs@FreeBSD.ORG Wed Apr 22 10:30:23 2009 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0501F1065670 for ; Wed, 22 Apr 2009 10:30:23 +0000 (UTC) (envelope-from gary.jennejohn@freenet.de) Received: from mout2.freenet.de (mout2.freenet.de [IPv6:2001:748:100:40::2:4]) by mx1.freebsd.org (Postfix) with ESMTP id 94DD48FC0A for ; Wed, 22 Apr 2009 10:30:22 +0000 (UTC) (envelope-from gary.jennejohn@freenet.de) Received: from [195.4.92.18] (helo=8.mx.freenet.de) by mout2.freenet.de with esmtpa (ID gary.jennejohn@freenet.de) (port 25) (Exim 4.69 #88) id 1LwZif-0002Zy-90; Wed, 22 Apr 2009 12:30:21 +0200 Received: from tb821.t.pppool.de ([89.55.184.33]:33573 helo=ernst.jennejohn.org) by 8.mx.freenet.de with esmtpa (ID gary.jennejohn@freenet.de) (port 25) (Exim 4.69 #79) id 1LwZie-0005QL-Tt; Wed, 22 Apr 2009 12:30:21 +0200 Date: Wed, 22 Apr 2009 12:30:20 +0200 From: Gary Jennejohn To: Kai Gallasch Message-ID: <20090422123020.42b756c1@ernst.jennejohn.org> In-Reply-To: <49EE49D8.7000902@free.de> References: <49EE49D8.7000902@free.de> X-Mailer: Claws Mail 3.7.1 (GTK+ 2.14.7; amd64-portbld-freebsd8.0) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: freebsd-fs@freebsd.org Subject: Re: FreeBSD 7.2-RC1 - ZFS related kernel panic "kmem_map too small" X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: gary.jennejohn@freenet.de List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Apr 2009 10:30:23 -0000 On Wed, 22 Apr 2009 00:34:00 +0200 Kai Gallasch wrote: [snip a lot of stuff] > In /usr/src/UPDATING I read: > > [..] > > 20090207: > ZFS users on amd64 machines with 4GB or more of RAM should > reevaluate their need for setting vm.kmem_size_max and > vm.kmem_size manually. In fact, after recent changes to the > kernel, the default value of vm.kmem_size is larger than the > suggested manual setting in most ZFS/FreeBSD tuning guides. > > So I understood this as "vm.kmem_size is set unnecessary large by > default. You should think about decreasing it to save some RAM" > > On my amd64 server the default values of kmem_size are > > vm.kmem_size_scale: 3 > vm.kmem_size_max: 3865468109 > vm.kmem_size_min: 0 > vm.kmem_size: 1201446912 > > Can someone give me a hint how to debug this problem further, or how to > find some reasonable values for setting vm.kmem_size_max and > vm.kmem_size with 16G of RAM? > Hmm, I wonder whether this applies to 7.2-RC1. I don't know whether the kernel changes have been committed to 7.2 or whether they were already present when we started work on 7.2 because I haven't been paying much attention. On my 8-current amd64 machine with only 4GB of RAM I see larger values than you see with 16GB: sysctl vm.kmem_size_max vm.kmem_size_max: 4509713203 sysctl vm.kmem_size vm.kmem_size: 1335824384 --- Gary Jennejohn