ZFS kmem_map too small.

[Pawel Jakub Dawidek]

On Wed, Nov 07, 2007 at 08:46:35AM +0100, Martijn Plak wrote:
> My 7.0-BETA2 (+ updates) system is crashing regularly on a kmem_map  
> too small panic too.
> Yesterday I applied the vm_kern.c.2.patch patch and turned off all of  
> my sysctl tweaks.
> 
> At first, the system was stable for a day. During that day, I ran   
> make -j4 buildworld several times without trouble.
> 
> Then started a network transfer. This was a usenet download, on 4 TCP  
> channels, for a total of 10Mbps, from a server at a 'ping distance'  
> of about 20ms, using hellanzb.py. My guess was that this sort of  
> transfer puts some memory pressure on the kernel space.  Running that  
> in parallel with the buildworld crashed the system again.
> 
> I hope this helps the investigation. Let me know if I can run other  
> tests.
[...]
> === cat /boot/loader.conf
> # Load ZFS and load root system from the RAID-Z array.
> zfs_load="YES"
> vfs.root.mountfrom="zfs:raid/sys/root"
> 
> # Tune ZFS and VM parameters.
> #vfs.zfs.arc_max="64M"
> #kern.maxvnodes="50000"
> #vm.kmem_size_max="512M"
> #vm.kmem_size="512M"
> === sysctl vm | grep kmem
> vm.kmem_size_scale: 3
> vm.kmem_size_max: 335544320
> vm.kmem_size_min: 0
> vm.kmem_size: 335544320

The only tuning that is needed (and ZFS will warn now about this) is
vm.kmem_size/vm.kmem_size_max. Can you set those back to 512M and retry?

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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