Is there any way to increase the KVM?

Ivan Voras ivoras at
Thu Jun 5 14:00:23 UTC 2008

Pawel Jakub Dawidek wrote:

> If we're comparing who has bigger... :)
> beast:root:~# zpool list
> NAME                    SIZE    USED   AVAIL    CAP  HEALTH     ALTROOT
> tank                    732G    604G    128G    82%  ONLINE     -
> but:
> beast:root:~# zfs list | wc -l
>     1932
> No panics.
> PS. I'm quite sure the ZFS version I've in perforce will fix most if not
> all 'kmem_map too small' panics. It's not yet committed, but I do want
> to MFC it into RELENG_7.

At the risk of sounding repetitive, can you try a simple test on your
ZFS pools, to see if you can panic the kernel? Do this:

* install blogbench and bonnie++ from ports/benchmarks
* run:
	blogbench -c 100 -d . -i 30 -r 50 -W 10 -w 10
	bonnie++ -d . -s 16G -n 80
  in parallel, until completion or crash. It shouldn't take too long to
complete the above benchmarks, so you probably won't invest too much
time in it even if it doesn't crash.

(note: in the above command lines, "." is the current working directory,
which is on ZFS, and "16G" is "2*RAM size". Keep the "-s" argument high
even if you don't have lots of RAM.)

This assumes you have a multi-core machine on which ZFS is running. 4
would be nice, 2 is probably ok.

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