ZFS kmem_map too small.

[Darren Reed]

Pawel Jakub Dawidek wrote:
> Hi.
> 
> We'are about to branch RELENG_7 and I'd like to start discussion with
> folks that experience 'kmem_map too small' panic with the latest HEAD.
> 
> I'm trying hard to reproduce it and I can't, so I need to gather more
> info how you are able to provoke this panic.

Hmm, the first and only time it happened to me was when running cvsup
on the rsync'd freebsd CVS tree after creating a snapshot of it.  I've
repeated that exercise since (and many times before) with no problems.

That was when I mistakingly had the ARC max set to be maybe 10MB or
so smaller than the kmem_map size (this was a mistake.)  I've since
grown that gap to 100MB.

Tips on how to reproduce it?  Make the kmem_map size small and set the
ARC's maximum size to be the same as it ? :)

Darren