Messages in this thread | | | Date | Wed, 24 Jun 2009 17:13:37 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support |
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Andi Kleen wrote: > > Haven't read the new patches, but per cpu data always was sized > for all possible CPUs. > >> and N is large, what did it cost? > >> And what are reasonable values of N? > > N should normally not be large anymore, since num_possible_cpus() > is sized based on firmware information now. >
*Ahem* virtual machines *ahem*...
I have discussed this with Tejun, and the plan is to allocate the percpu information when a processor is first brought online (but not removed when it is offlined again.) It's a real problem for 32-bit VMs, so it's more important than you'd think.
-hpa
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