Is there any way to increase the KVM?

[Jeremy Chadwick]

On Sat, May 31, 2008 at 12:49:53PM -0400, John Baldwin wrote:
> On Saturday 31 May 2008 01:52:56 am Tz-Huan Huang wrote:
> > Hi,
> >
> > Our nfs server is running 7-stable/amd64 with 8G ram, the size of zfs
> > pool is 12T. We have set vm.kmem_size and vm.kmem_size_max to
> > 1.5G, but the kernel still panics by "kmem_map too small" often.
> > According to [1], the limitation is not only by the loader (is it fixed
> > now?) but also by the default layout of KVM. [2] points a way to increase
> > the KVM, but we get the similar linking error.
> >
> > Is there any standard way to modify the layout of KVM? For example, we
> > may want to set KVM to 6G and leave the 2G for user space usage.
> 
> On i386 you only have 4GB of virtual address space period.  For amd64 you can 
> jack up KVM just fine AFAIK.  The mcmodel=kernel stuff should only affect 
> global variables (so .data and .bss) and not malloc'd stuff.  Have you tried 
> increasing the KVM size and seeing what happens?

On amd64 there's still a 2GB limit, re: vm.kmem_size.  Increasing it
to or past 2048M results in the message "kmem_suballoc(): bad status
return of 3".

http://lists.freebsd.org/pipermail/freebsd-stable/2008-May/042764.html

-- 
| 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 |