Re: NUMA aware slab allocator V3

[Matthew Dobson <colpatch@us.ibm.com>]

Christoph Lameter wrote:
> On Wed, 18 May 2005, Christoph Lameter wrote:
> 
>>Fixes to the slab allocator in 2.6.12-rc4-mm2
>>- Remove MAX_NUMNODES check
>>- use for_each_node/cpu
>>- Fix determination of INDEX_AC
> 
> Rats! The whole thing with cpu online and node online is not as easy as I 
> thought. There may be bugs in V3 of the numa slab allocator 
> because offline cpus and offline are not properly handled. Maybe 
> that also contributed to the ppc64 issues. 

Running this test through the "wringer" (aka building/booting on one of our
PPC64 boxen).  I'll let you know if this fixes any problems.


> The earlier patch fails if I boot an x86_64 NUMA kernel on a x86_64 single 
> processor system.
> 
> Here is a revised patch. Would be good if someone could review my use 
> of online_cpu / online_node etc. Is there some way to bring cpus 
> online and offline to test if this really works? Seems that the code in 
> alloc_percpu is suspect even in the old allocator because it may have
> to allocate memory for non present cpus.

I'll look through and see what I can tell you, but I gotta run to a meeting
now. :(

-Matt