Is there any way to increase the KVM?

[Tz-Huan Huang]

On Sun, Jun 1, 2008 at 12:49 AM, John Baldwin <jhb at freebsd.org> 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?

Actaully I have no idea how to increase the KVM size ... Should I change some
knobs on kernel conifg or some codes?

When setting the vm.kmem_size to almost or more than 2G, the kernel panics
immediately after booting. When I change the KPDPI like [1], I have
linking error.

Thanks,
Tz-Huan

[1] http://lists.freebsd.org/pipermail/freebsd-current/2008-March/084325.html