On 28-02-18, 12:22, Rafael J. Wysocki wrote: > On Wed, Feb 28, 2018 at 12:06 PM, Claudio Scordino > <[email protected]> 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 <[email protected]> > > CC: Ingo Molnar <[email protected]> > > CC: Patrick Bellasi <[email protected]> > > CC: Dietmar Eggemann <[email protected]> > > CC: Morten Rasmussen <[email protected]> > > CC: Juri Lelli <[email protected]> > > CC: Viresh Kumar <[email protected]> > > CC: Vincent Guittot <[email protected]> > > CC: Todd Kjos <[email protected]> > > CC: Joel Fernandes <[email protected]> > > CC: [email protected] > > CC: [email protected] > > --- > > 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
