Re: [PATCHSET] percpu: generalize first chunk allocators andimprove lpage NUMA support

From: Ingo Molnar
Date: Tue Jun 30 2009 - 19:31:34 EST



* Tejun Heo <tj@xxxxxxxxxx> wrote:

> Hello, Christoph.
>
> Christoph Lameter wrote:

> > I looked at allocating for online cpus only a couple of years
> > back but at that per cpu state was kept for offlined cpus in per
> > cpu areas. There are numerous assumptions in per cpu handling
> > all over the kernel that a percpu area is always available.
>
> The plan is to allocate and keep percpu areas for cpus which have
> ever been up. There'll be no taking down of percpu areas.
> Conversion from possible to has_ever_been_up should be much easier
> than possible -> online. State keeping will work fine too.

That sounds like a very sane plan.

Ingo
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