When will ZFS become stable?

Ivan Voras ivoras at freebsd.org
Sun Jan 6 09:21:07 PST 2008


Kris Kennaway wrote:

>  > Better yet, why not
>> increase both vm.kmem_size and KVA_PAGES to (the equivalent of) 640 MB 
>> or 768 MB by default for 7.0?
> 
> That is answered in the tuning guide.  Tuning KVA_PAGES by default is 
> not appropriate.

Ok. I'd like to understand what is the relationship between KVA_PAGES 
and vm.kmem_size. The tuning guide says:

"""By default the kernel receives 1GB of the 4GB of address space 
available on the i386 architecture, and this is used for all of the 
kernel address space needs, not just the kmem map. By increasing 
KVA_PAGES you can allocate a larger proportion of the 4GB address 
space..."""

and:

"""recompile your kernel with increased KVA_PAGES option, to increase 
the size of the kernel address space, before vm.kmem_size can be 
increased beyond 512M"""

What is the other 512 MB of the 1 GB used for?



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