Re: [git] CFS-devel, group scheduler, fixes

[Tong Li <tong.n.li@intel.com>]

On Mon, 24 Sep 2007, Peter Zijlstra wrote:

> On Mon, 24 Sep 2007 13:22:14 +0200 Mike Galbraith <efault@gmx.de> wrote:
>
> > On Mon, 2007-09-24 at 12:42 +0200, Mike Galbraith wrote:
> > > On Mon, 2007-09-24 at 12:24 +0200, Peter Zijlstra wrote:
> > >
> > > > how about something like:
> > > >
> > > >  s64 delta = (s64)(vruntime - min_vruntime);
> > > >  if (delta > 0)
> > > >   min_vruntime += delta;
> > > >
> > > > That would rid us of most of the funny conditionals there.
> > >
> > > That still left me with negative min_vruntimes.  The pinned hogs didn't
> > > lock my box up, but I quickly got the below, so hastily killed it.
> >
> > Shouldn't the max() in place_entity() be the max_vruntime() that my
> > lysdexia told me it was when I looked at it earlier? ;-)
>
> probably, my tree doesn't have that max anymore so I'm not sure.

Last time I looked, I thought the max() in place_entity() was fine and the 
problem seemed to be in set_task_cpu() that was causing the negative 
vruntimes:

        if (likely(new_rq->cfs.min_vruntime))
                p->se.vruntime -= old_rq->cfs.min_vruntime -
                                                new_rq->cfs.min_vruntime;

I think it's fine we get rid of sync_vruntime(). I need to think more 
about how to make global fairness work based on this--it seems to be more 
complicated than if we had sync_vruntime().

  tong
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