Messages in this thread | | | Date | Tue, 30 Jun 2009 16:34:05 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support |
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Ingo Molnar wrote: > * Tejun Heo <tj@kernel.org> 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
Yes, percpu area dynamic *de*-allocation would almost certainly be a nightmare.
-hpa
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