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

[Glauber Costa]

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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