Date: Thu, 25 Sep 2008 06:02:27 -0700 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Bartosz Stec <admin@kkip.pl> Cc: freebsd-stable@freebsd.org Subject: Re: vm.kmem_size settings doesn't affect loader? Message-ID: <20080925130227.GA13497@icarus.home.lan> In-Reply-To: <48DB6772.1060400@kkip.pl> References: <48DB6772.1060400@kkip.pl>
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On Thu, Sep 25, 2008 at 12:26:58PM +0200, Bartosz Stec wrote: > > > Today I've experienced zfs-related kernel panic. Log says: > > savecore: reboot after panic: kmem_malloc(131072): kmem_map too > small: 327684096 total allocated > > Reported amount of memory (327684096) is wrong, because i made suggested > tuning in my loader.conf: > > vm.kmem_size="512M" > vm.kmem_size_max="512M" > > Just to be sure: > > # sysctl vm | grep kmem > vm.kmem_size: 536870912 > vm.kmem_size_min: 0 > vm.kmem_size_max: 536870912 > vm.kmem_size_scale: 3 > > Am I missing something? I believe this is normal. The amount shown in "total allocated" will not match what you have vm.kmem_size or vm.kmem_size_max set to. Someone more familiar with the VM can explain why this is, but as I understand it, it's 100% normal. Your options are: 1) Consider increasing it from 512M to something like 1.5GB; do not increase it past that on RELENG_7, as there isn't support for more than 2GB total. For example, on a 1GB memory machine, I often recommend 768M. On 2GB machines, 1536M. You will need to run -CURRENT if you want more. 2) Tune ZFS aggressively. Start by setting vfs.zfs.arc_min="16M" and vfs.zfs.arc_max="64M". If your machine has some small amount of memory (768MB, 1GB, etc.), then you probably shouldn't be using ZFS. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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