Re: [RFD 4/9] Make total_forks per-cgroup

[Glauber Costa]

On 09/28/2011 09:53 AM, Peter Zijlstra wrote:
> On Wed, 2011-09-28 at 14:42 +0200, Martin Schwidefsky wrote:
>
> > > That is, am I missing some added value of all this cputime*() foo?
> >
> > C can do the math as long as the encoding of the cputime is simple enough.
> > Can we demand that a cputime value needs to be an integral type ?
>
> I'd like to think we can ;-)
>
> > What I did when I wrote all that stuff is to define cputime_t as a struct
> > that contains a single u64. That way I found all the places in the kernel
> > that used a cputime and could convert the code accordingly.
>
> Indeed, that makes it a non-simple type and breaks all the C arith bits.
>
> > My fear is that if the cputime_xxx operations are removed, code will
> > sneak in again that just uses an unsigned long instead of a cputime_t.
> > That would break any arch that requires something bigger than a u32 for
> > its cputime.
>
> Which is only a problem for 32bit archs, of which s390 is the only one
> that matters, right? Hurm,. could we do something with sparse? Lots of
> people run sparse.
Well, I think x86-32 is unlikely to ever really go away.
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