Re: linux-next: manual merge of the tip tree with the cputime tree

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On 12/19/2011 06:08 PM, Peter Zijlstra wrote:
On Mon, 2011-12-19 at 13:31 +0100, Martin Schwidefsky wrote:
Just one question: are you sure that you want the cpustat array
to be u64 instead of cputime64_t? The content of the cpustat array is defined
by the architecture semantics of cputime64_t, for CONFIG_VIRT_CPU_ACCOUNTING=y
this is not a jiffy counter. If the array is u64 we won't get the sparse
checking when reading from cpustat.

So as Glauber said the reason was that we wanted to use simply
operators, and IIRC he wanted to add a few fields that had to be u64.

I'm not sure what the current plans are wrt adding more fields, but with
your work cputime_t should again be a simple type and thus regular math
operators should work again, right?

Glauber, do you still need to add fields?

Due to the current state of discussions of cpu vs cpuacct, I think the final state of this is quite unclear. However, I think Martin's work is a quite worthwhile piece for us to have. So last case we can add extra fields in a different array and tell them apart by the index, etc. It shouldn't be expensive at all.


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