Messages in this thread | | | Date | Thu, 25 Jun 2009 21:54:08 +0200 | From | Andi Kleen <> | Subject | Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support |
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On Thu, Jun 25, 2009 at 07:18:07AM -0700, H. Peter Anvin wrote: > Andi Kleen wrote: > >>> > >> *Ahem* virtual machines *ahem*... > > > > And? Even there's not that big typically. > > > > The traditional problem was just for 128 NR_CPUs kernel were nothing > > was sized based on machine capacity. > > > > Also on large systems the VMs shouldn't be sized for full capacity. > > > > We have already have cases where the "possible" CPUs have eaten up the > entire vmalloc area on 32 bits. In real use. It's a real problem.
That's hard to believe or a serious bug/misconfiguration somewhere.
Each per CPU data should be <100k (let's say 200k with some slack for modules), so to fill vmalloc you would need hundreds of CPUs, which a 32bit kernel doesn't really support anyways because it doesn't support enough memory for that many CPUs.
Perhaps you had firmware/hypervisor who passed a gigantic impossible value here? If yes thy
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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