Re: When will ZFS become stable?

Vadim Goncharov wrote:
> 06.01.08 _at_ 23:34 Kris Kennaway wrote:
> 
>>> What is the other 512 MB of the 1 GB used for?
>>
>> Everything else that the kernel needs address space for.  Buffer 
>> cache, mbuf allocation, etc.
> 
> Aren't they allocated from the same memory zones? I have a router with 
> 256 Mb RAM, it had a panic with ng_nat once due to exhausted kmem. So, 
> what these number from it's sysctl do really mean?
> 
> vm.kmem_size: 83415040
> vm.kmem_size_max: 335544320
> vm.kmem_size_scale: 3
> vm.kvm_size: 1073737728
> vm.kvm_free: 704638976
> 

I believe that mbufs are allocated from a separate map.  In your case 
you only have ~80MB available in your kmem_map, which is used for 
malloc() in the kernel.  It is possible that ng_nat in combination with 
the other kernel malloc usage exhausted this relatively small amount of 
space without mbuf use being a factor.

Kris