ZFS not caching right?

[Craig Boston]

On Mon, Sep 10, 2007 at 09:58:33PM +0200, Pawel Jakub Dawidek wrote:
> Can you try recent HEAD? I committed a change that allows ZFS cache
> (ARC) to use more memory. This should be safe after dfr@'s vnode leak
> fix and should also help performance.

FYI, I've started getting kmem_map too small panics again after this
change, on i386.

2GB physical RAM
vm.kmem_size: 671088640		(set in loader.conf)
kern.maxvnodes: 75000		(down from the autotuned value of 100000)
vfs.zfs.arc_min: 20971520
vfs.zfs.arc_max: 503316480
vfs.zfs.vdev.cache.size: 10485760
vfs.zfs.vdev.cache.max: 16384

Current values from a live system:
kstat.zfs.misc.arcstats.c_min: 20971520
kstat.zfs.misc.arcstats.c_max: 503316480
kstat.zfs.misc.arcstats.size: 321891840

The panic showed "kmem_malloc(1568768): kmem_map too small: 458543104
total allocated" last time it happened.  640MB for kmem is pretty close
to the max I can bump it up to before the system no longer boots for
whatever reason.

Let me know if I'm missing any relevant stats...

Craig