On 28-02-18, 12:22, Rafael J. Wysocki wrote: > On Wed, Feb 28, 2018 at 12:06 PM, Claudio Scordino > <clau...@evidence.eu.com> 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 with up to 10 SCHED_DEADLINE tasks have > > shown reductions of even 10% of deadline misses with a negligible > > increase of energy consumption (measured through Baylibre Cape). > > > > Signed-off-by: Claudio Scordino <clau...@evidence.eu.com> > > CC: Ingo Molnar <mi...@redhat.com> > > CC: Patrick Bellasi <patrick.bell...@arm.com> > > CC: Dietmar Eggemann <dietmar.eggem...@arm.com> > > CC: Morten Rasmussen <morten.rasmus...@arm.com> > > CC: Juri Lelli <juri.le...@redhat.com> > > CC: Viresh Kumar <viresh.ku...@linaro.org> > > CC: Vincent Guittot <vincent.guit...@linaro.org> > > CC: Todd Kjos <tk...@android.com> > > CC: Joel Fernandes <joe...@google.com> > > CC: linux...@vger.kernel.org > > CC: linux-kernel@vger.kernel.org > > --- > > Changes from v1: > > - Logic moved from sugov_should_update_freq() to > > sugov_update_single()/_shared() to not duplicate data structures > > - Rate limit not ignored in case of "fast switch" > > I'm not sure about this last bit. > > IMO you can set sg_policy->need_freq_update even in the "fast switch" > case to start with and special case it in the future if that turns out > to be problematic. That is, unless you have data indicating that it > already is problematic, of course. :-) > > > --- > > kernel/sched/cpufreq_schedutil.c | 16 ++++++++++++++++ > > 1 file changed, 16 insertions(+) > > > > diff --git a/kernel/sched/cpufreq_schedutil.c > > b/kernel/sched/cpufreq_schedutil.c > > index 7936f54..ca6ce72 100644 > > --- a/kernel/sched/cpufreq_schedutil.c > > +++ b/kernel/sched/cpufreq_schedutil.c > > @@ -273,6 +273,14 @@ static void sugov_update_single(struct > > update_util_data *hook, u64 time, > > sugov_set_iowait_boost(sg_cpu, time); > > sg_cpu->last_update = time; > > > > + /* > > + * Make sugov_should_update_freq() ignore the rate limit when DL > > + * has increased the utilization. > > + */ > > + if ((cpu_util_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->util_dl) && > > + !(sg_policy->policy->fast_switch_enabled)) > > + sg_policy->need_freq_update = true; > > +
And a new routine for this block would be good as well. -- viresh
