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

[Glauber Costa]

On 09/28/2011 12:33 PM, Peter Zijlstra wrote:
> On Wed, 2011-09-28 at 12:29 -0300, Glauber Costa wrote:
> > 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.
>
> Sadly I'd agree with you, but that's not really the point, the only 32
> bit arch that has !32 bit cputime_t is s390.

Ah, I see.

Right, then.

So let me get this straight: The proposal here is really to get rid of 
all cputime_t , not only cputime64_t ?

> But yeah, death to ia32 (and everything else 32bit fwiw)!
Well, we need to kill the 16bit stuff still lying around first =)

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