Messages in this thread | | | Date | Tue, 20 Nov 2007 17:16:11 -0800 (PST) | From | Christoph Lameter <> | Subject | Re: [rfc 08/45] cpu alloc: x86 support |
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But one can subtract too... Hmmm... So the cpu area 0 could be put at the beginning of the 2GB kernel area and then grow downwards from 0xffffffff80000000. The cost in terms of code is one subtract instruction for each per_cpu() or CPU_PTR()
The next thing doward from 0xffffffff80000000 is the vmemmap at 0xffffe20000000000, so ~32TB. If we leave 16TB for the vmemmap (a 16TB vmmemmap be able to map 2^(44 - 6 + 12) = 2^50 bytes more than currently supported by the processors)
then the remaining 16TB could be used to map 1GB per cpu for a 16k config. That is wildly overdoing it. Guess we could just do it with 1M anyways. Just to be safe we could do 128M. 128M x 16k = 2TB?
Would such a configuration be okay?
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