Re: Memory Allocators

[David Young <dyoung%pobox.com@localhost>]

On Mon, Dec 06, 2010 at 11:42:27AM +0100, Lars Heidieker wrote:
> To whom it may be of concern,
> 
> I just got my thoughts around the different memory allocators in the
> NetBSDs kernel. It seems to me that there is quite a lot of
> duplication and some clean up would be needed.
> I think it would be nice to get rid of the old malloc. the kmem/vmem
> could be used in such a case but this brings me to another point, the
> vmem is designed to slice integer spaces eg addresses or whatever,
> therefor it would be suited to slice the kernels virtual address space
> like in solaris but this is only the case for the kmem not for the
> pool memory and furthermore the allocation of virtual address space
> for kemm/vmem is backed by the uvm_kern/uvm_map system as well, seems
> like some duplication to me.
> Either a solution which uses the vmem to slice the kernel space and
> not using the uvm_kern/uvm_map stuff for that or backing the pool/kmem
> with the uvm_kern/uvm_map system would be feasible. I do prefer the
> later solution as getting the recursion in vmem right is quite hard
> and to use vmem as a replacement for extend.

Lars,

I tried to replace extent(9) with vmem(9) in the kernel, and I found
some bugs in the vmem(9) API & implementation.  I discussed my results
at <http://mail-index.netbsd.org/tech-kern/2009/12/03/msg006566.html>.
Maybe you would like to pick up from where I left off?

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933