Re: [PATCH] cpufreq: schedutil: rate limits for SCHED_DEADLINE

[Rafael J. Wysocki]

On Friday, February 9, 2018 9:02:34 AM CET Claudio Scordino wrote:
> Hi Viresh,
> 
> Il 09/02/2018 04:51, Viresh Kumar ha scritto:
> > On 08-02-18, 18:01, Claudio Scordino wrote:
> >> When the SCHED_DEADLINE scheduling class increases the CPU utilization,
> >> we should not wait for the rate limit, otherwise we may miss some deadline.
> >>
> >> Tests using rt-app on Exynos5422 have shown reductions of about 10% of deadline
> >> misses for tasks with low RT periods.
> >>
> >> The patch applies on top of the one recently proposed by Peter to drop the
> >> SCHED_CPUFREQ_* flags.
> >>

[cut]

> 
> > 
> > Is it possible to (somehow) check here if the DL tasks will miss
> > deadline if we continue to run at current frequency? And only ignore
> > rate-limit if that is the case ?
> 
> I need to think further about it.

That would be my approach FWIW.

Increasing the frequency beyond what is necessary means wasting energy
in any case.

Thanks,
Rafael