Re: Tuning KVA_PAGES / kmem?

On Tue, 2004-04-20 at 07:14, Stefan Bethke wrote:
> Hi,
> 
> I'm struggling a bit with a box I'm setting up right now: 2x Xeon 2.8  
> GHz with 6 GB RAM. Main disk is a RAID 5 on 3ware controller. I'm  
> running -current from around Easter.
> 
> Occasionally, the machine panics with:
> panic: kmem_malloc(4096): kmem_map too small: 275251200 total allocated
> at line 337 in file /usr/src/sys/vm/vm_kern.c
> 
> I had stability problems when I was using PAE, so I disabled that for  
> the moment; even when running GENERIC, I get this panic.
> 
> I dug through the archives, and I found some hints that with >>2 GB  
> RAM, the auto-tuning might produce undesirable results, so I might need  
> to tune KVA_PAGES to reserve more address space for the kernel, or  
> fiddle with VM_KMEM_SIZE_MAX, VM_KMEM_SIZE_SCALE, or some vm sysctls.
> 
> Can someone point me in the right direction?
> 
> 
> Thanks,
> Stefan

The following link has been posted here on occasion and it serves as a
nice reference (IMESHO) to the relations between kva_pages,
vm_kmem_size_scale, etc. I found it useful when experiencing similar
errors, albeit with less RAM.

http://unix.derkeiler.com/Mailing-Lists/FreeBSD/current/2003-06/1599.html

Sven