6.3-RELEASE-p3 recurring panics on multiple SM PDSMi+

[Royce Williams]

Kris Kennaway wrote, on 7/22/2008 12:12 PM:
> Royce Williams wrote:
> 
>> db> trace
>> Tracing pid 71182 tid 100325 td 0xcc08b180
>> kdb_enter(c095f294) at kdb_enter+0x2b
>> panic(c09768ad,1000,14000000,c145bc88,1000,...) at panic+0x127
>> kmem_malloc(c14680c0,1000,102,eba6a8cc,c07e3fa5,...) at kmem_malloc+0x89
> 
> You forgot to include the panic

Is there is a way to get the panic after dropping into the debugger?
This serial console setup has no scrollback, so I couldn't see the
preceding text.

> but this is probably the "kmem_map too small" panic.  

Ah, I see this now, at faq/book.html#KMEM-MAP-TOO-SMALL:

"Compile your own kernel, and add the VM_KMEM_SIZE_MAX to your kernel
configuration file, increasing the maximum size to 400 MB (options
VM_KMEM_SIZE_MAX=419430400). 400 MB appears to be sufficient for
machines with up to 6 GB of memory."


> It says that your kernel ran out of memory, and the
> solution is to fix that situation by giving more memory to the kernel.
> Increase the vm.kmem_size tunable until your system stops running out of
> memory on your workload.

Comparing the FAQ, kern_malloc.c and your mentioning it as tunable,
please clarify: is the Right Thing to do to use vm.kmem_size, or
vm.kmem_size_max?

I tried vm.kmem_size_max, which yields:

# sysctl -a | grep kmem
vm.kmem_size: 419430400
vm.kmem_size_max: 419430400
vm.kmem_size_scale: 3


Should I contribute some additional language to the FAQ, saying that
the vm.kmem_size[_max] tunable can be used without recompiling the kernel?

Royce


-- 
Royce D. Williams                                   - http://royce.ws/
Reproof should not exhaust its power upon petty failings. - S. Johnson