Re: [patch 2.6.16-rc5-mm2] sched_cleanup-V17 - task throttling patch 1 of 2

[Mike Galbraith <efault@gmx.de>]

On Sat, 2006-03-04 at 16:54 +1100, Con Kolivas wrote:
> On Saturday 04 March 2006 16:40, Randy.Dunlap wrote:
> > On Sat, 04 Mar 2006 06:29:47 +0100 Mike Galbraith wrote:
> > > On Sat, 2006-03-04 at 16:24 +1100, Con Kolivas wrote:
> > > > On Saturday 04 March 2006 16:20, Mike Galbraith wrote:
> > > > > On Sat, 2006-03-04 at 13:33 +1100, Peter Williams wrote:
> > > > > > >  include/linux/sched.h |    3 -
> > > > > > >  kernel/sched.c        |  136
> > > > > > > +++++++++++++++++++++++++++++--------------------- 2 files
> > > > > > > changed, 82 insertions(+), 57 deletions(-)
> > > > > > >
> > > > > > > --- linux-2.6.16-rc5-mm2/include/linux/sched.h.org	2006-03-01
> > > > > > > 15:06:22.000000000 +0100 +++
> > > > > > > linux-2.6.16-rc5-mm2/include/linux/sched.h	2006-03-02
> > > > > > > 08:33:12.000000000 +0100 @@ -720,7 +720,8 @@
> > > > > > >
> > > > > > >  	unsigned long policy;
> > > > > > >  	cpumask_t cpus_allowed;
> > > > > > > -	unsigned int time_slice, first_time_slice;
> > > > > > > +	int time_slice;
> > > > > >
> > > > > > Can you guarantee that int is big enough to hold a time slice in
> > > > > > nanoseconds on all systems?  I think that you'll need more than 16
> > > > > > bits.
> > > > >
> > > > > Nope, that's a big fat bug.
> > > >
> > > > Most ints are 32bit anyway, but even a 32 bit unsigned int overflows
> > > > with nanoseconds at 4.2 seconds. A signed one at about half that. Our
> > > > timeslices are never that large, but then int isn't always 32bit
> > > > either.
> > >
> > > Yup.  I just didn't realize that there were 16 bit integers out there.
> >
> > LDD 3rd ed. doesn't know about them either.  Same for me.
> 
> Alright I made that up, but it might not be one day :P

Well Fudgecicles.  Now you guys have gotten me aaaaall confused.  Are
there cpus out there (in generic linux land) that have 16 bit integers
or not?  16 bit integers existing in a 32 bit cpu OS seems like an alien
concept to me, but I'm not a twisted cpu designer... I'll just go with
the flow ;-)

	-Mike

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