Re: [patch 00/41] cpu alloc / cpu ops v3: Optimize per cpu access

Mike Travis
2008-05-30T14:38:45Z

Christoph Lameter wrote:
> On Thu, 29 May 2008, Andrew Morton wrote:
...
>> Plus who knows what lies ahead of us?
>
> Well invariably we will end up with cpu area defragmentation.... Sigh.
>
>> I don't think there is presently any upper limit on alloc_percpu()? It
>> uses kmalloc() and kmalloc_node()?
>>
>> Even if there is some limit, is it an unfixable one?
>
> No there is no limit. It just wastes lots of space (pointer arrays,
> alignment etc) that we could use to configure sufficiently large per cpu
> areas.

Is there any reason why the per_cpu area couldn't be made extensible? Maybe
a simple linked list of available areas? (And use a config variable and/or
boot param for initial size and increment size?) [Ignoring the problem of
reclaiming the space...]