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

[Con Kolivas <kernel@kolivas.org>]

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.

Cheers,
Con