On Thu, 21 Jun 2018 at 20:57, Peter Zijlstra <pet...@infradead.org> wrote:
>
> On Thu, Jun 21, 2018 at 08:45:24PM +0200, Peter Zijlstra wrote:
> > On Fri, Jun 08, 2018 at 02:09:47PM +0200, Vincent Guittot wrote:
> > > static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
> > > {
> > > struct rq *rq = cpu_rq(sg_cpu->cpu);
> > > + unsigned long util;
> > >
> > > if (rq->rt.rt_nr_running)
> > > return sg_cpu->max;
> > >
> > > + util = sg_cpu->util_dl;
> > > + util += sg_cpu->util_cfs;
> > > + util += sg_cpu->util_rt;
> > > +
> > > /*
> > > * Utilization required by DEADLINE must always be granted while, for
> > > * FAIR, we use blocked utilization of IDLE CPUs as a mechanism to
> > > @@ -197,7 +204,7 @@ static unsigned long sugov_aggregate_util(struct
> > > sugov_cpu *sg_cpu)
> > > * util_cfs + util_dl as requested freq. However, cpufreq is not yet
> > > * ready for such an interface. So, we only do the latter for now.
> > > */
> > > - return min(sg_cpu->max, (sg_cpu->util_dl + sg_cpu->util_cfs));
> > > + return min(sg_cpu->max, util);
> > > }
> >
> > So this (and the dl etc. equivalents) result in exactly the problems
> > complained about last time, no?
> >
> > What I proposed was something along the lines of:
> >
> > util = 1024 * sg_cpu->util_cfs;
> > util /= (1024 - (sg_cpu->util_rt + sg_cpu->util_dl + ...));
> >
> > return min(sg_cpu->max, util + sg_cpu->bw_dl);
I see that you use sg_cpu->util_dl and sg_cpu->bw_dl in your equation
above but this patch 04 only adds rt util_avg and the dl util_avg has
not been added yet.
dl util_avg is added in patch 6
So for this patch, we are only using sg_cpu->bw_dl
> >
> > Where we, instead of directly adding the various util signals.
>
> That looks unfinished; I think that wants to include: "we renormalize
> the CFS signal".
>
> > I now see an email from Quentin asking if these things are not in fact
> > the same, but no, they are not. The difference is that the above only
> > affects the CFS signal and will re-normalize the utilization of an
> > 'always' running task back to 1 by compensating for the stolen capacity.
> >
> > But it will not, like these here patches, affect the OPP selection of
> > other classes. If there is no CFS utilization (or very little), then the
> > renormalization will not matter, and the existing DL bandwidth
> > compuation will be unaffected.
> >
