[PATCH v4] cpufreq: schedutil: rate limits for SCHED_DEADLINE

[PATCH v4] cpufreq: schedutil: rate limits for SCHED_DEADLINE

[Claudio Scordino]

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 <claudio@evidence.eu.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
CC: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
CC: Viresh Kumar <viresh.kumar@linaro.org>
CC: Patrick Bellasi <patrick.bellasi@arm.com>
CC: Dietmar Eggemann <dietmar.eggemann@arm.com>
CC: Morten Rasmussen <morten.rasmussen@arm.com>
CC: Juri Lelli <juri.lelli@redhat.com>
CC: Vincent Guittot <vincent.guittot@linaro.org>
CC: Todd Kjos <tkjos@android.com>
CC: Joel Fernandes <joelaf@google.com>
CC: linux-pm@vger.kernel.org
CC: linux-kernel@vger.kernel.org
---
Changes from v3:
 - Specific routine renamed as ignore_dl_rate_limit()
---
Changes from v2:
 - Rate limit ignored also in case of "fast switch"
 - Specific routine added
---
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"
---
 kernel/sched/cpufreq_schedutil.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index feb5f89..2aeb1ca 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -257,6 +257,16 @@ static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 #endif /* CONFIG_NO_HZ_COMMON */
 
+/*
+ * Make sugov_should_update_freq() ignore the rate limit when DL
+ * has increased the utilization.
+ */
+static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
+{
+	if (cpu_util_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->util_dl)
+		sg_policy->need_freq_update = true;
+}
+
 static void sugov_update_single(struct update_util_data *hook, u64 time,
 				unsigned int flags)
 {
@@ -270,6 +280,8 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
 	sugov_set_iowait_boost(sg_cpu, time);
 	sg_cpu->last_update = time;
 
+	ignore_dl_rate_limit(sg_cpu, sg_policy);
+
 	if (!sugov_should_update_freq(sg_policy, time))
 		return;
 
@@ -351,6 +363,8 @@ sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
 
 	raw_spin_lock(&sg_policy->update_lock);
 
+	ignore_dl_rate_limit(sg_cpu, sg_policy);
+
 	sugov_get_util(sg_cpu);
 	sg_cpu->flags = flags;
 
-- 
2.7.4

Re: [PATCH v4] cpufreq: schedutil: rate limits for SCHED_DEADLINE

[Viresh Kumar]

On 13-03-18, 11:35, 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 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 <claudio@evidence.eu.com>
> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> CC: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> CC: Viresh Kumar <viresh.kumar@linaro.org>
> CC: Patrick Bellasi <patrick.bellasi@arm.com>
> CC: Dietmar Eggemann <dietmar.eggemann@arm.com>
> CC: Morten Rasmussen <morten.rasmussen@arm.com>
> CC: Juri Lelli <juri.lelli@redhat.com>
> CC: Vincent Guittot <vincent.guittot@linaro.org>
> CC: Todd Kjos <tkjos@android.com>
> CC: Joel Fernandes <joelaf@google.com>
> CC: linux-pm@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> ---
> Changes from v3:
>  - Specific routine renamed as ignore_dl_rate_limit()

LGTM. Thanks.

-- 
viresh

Re: [PATCH v4] cpufreq: schedutil: rate limits for SCHED_DEADLINE

[Joel Fernandes]

On Tue, Mar 13, 2018 at 4:15 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 13-03-18, 11:35, 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 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 <claudio@evidence.eu.com>
>> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
>> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> CC: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> CC: Viresh Kumar <viresh.kumar@linaro.org>
>> CC: Patrick Bellasi <patrick.bellasi@arm.com>
>> CC: Dietmar Eggemann <dietmar.eggemann@arm.com>
>> CC: Morten Rasmussen <morten.rasmussen@arm.com>
>> CC: Juri Lelli <juri.lelli@redhat.com>
>> CC: Vincent Guittot <vincent.guittot@linaro.org>
>> CC: Todd Kjos <tkjos@android.com>
>> CC: Joel Fernandes <joelaf@google.com>
>> CC: linux-pm@vger.kernel.org
>> CC: linux-kernel@vger.kernel.org
>> ---
>> Changes from v3:
>>  - Specific routine renamed as ignore_dl_rate_limit()
>
> LGTM. Thanks.

Nice! Thanks.

- Joel

Re: [PATCH v4] cpufreq: schedutil: rate limits for SCHED_DEADLINE

[Rafael J. Wysocki]

On Wednesday, March 14, 2018 2:27:53 AM CET Joel Fernandes wrote:
> On Tue, Mar 13, 2018 at 4:15 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > On 13-03-18, 11:35, 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 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 <claudio@evidence.eu.com>
> >> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> >> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >> CC: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >> CC: Viresh Kumar <viresh.kumar@linaro.org>
> >> CC: Patrick Bellasi <patrick.bellasi@arm.com>
> >> CC: Dietmar Eggemann <dietmar.eggemann@arm.com>
> >> CC: Morten Rasmussen <morten.rasmussen@arm.com>
> >> CC: Juri Lelli <juri.lelli@redhat.com>
> >> CC: Vincent Guittot <vincent.guittot@linaro.org>
> >> CC: Todd Kjos <tkjos@android.com>
> >> CC: Joel Fernandes <joelaf@google.com>
> >> CC: linux-pm@vger.kernel.org
> >> CC: linux-kernel@vger.kernel.org
> >> ---
> >> Changes from v3:
> >>  - Specific routine renamed as ignore_dl_rate_limit()
> >
> > LGTM. Thanks.
> 
> Nice! Thanks.

OK, the patch doesn't seem to depend on anything in -tip, so I'm going to
apply it.

Thanks!

[tip:sched/core] sched/cpufreq: Rate limits for SCHED_DEADLINE

[tip-bot for Claudio Scordino]

Commit-ID:  e97a90f7069b740575bcb1dae86596e0484b8957
Gitweb:     https://git.kernel.org/tip/e97a90f7069b740575bcb1dae86596e0484b8957
Author:     Claudio Scordino <claudio@evidence.eu.com>
AuthorDate: Tue, 13 Mar 2018 11:35:40 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 23 Mar 2018 22:48:22 +0100

sched/cpufreq: Rate limits for SCHED_DEADLINE

When the SCHED_DEADLINE scheduling class increases the CPU utilization, it
should not wait for the rate limit, otherwise it 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 <claudio@evidence.eu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Todd Kjos <tkjos@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/1520937340-2755-1-git-send-email-claudio@evidence.eu.com
---
 kernel/sched/cpufreq_schedutil.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 89fe78ecb88c..2b124811947d 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -267,6 +267,16 @@ static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 #endif /* CONFIG_NO_HZ_COMMON */
 
+/*
+ * Make sugov_should_update_freq() ignore the rate limit when DL
+ * has increased the utilization.
+ */
+static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
+{
+	if (cpu_util_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->util_dl)
+		sg_policy->need_freq_update = true;
+}
+
 static void sugov_update_single(struct update_util_data *hook, u64 time,
 				unsigned int flags)
 {
@@ -279,6 +289,8 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
 	sugov_set_iowait_boost(sg_cpu, time, flags);
 	sg_cpu->last_update = time;
 
+	ignore_dl_rate_limit(sg_cpu, sg_policy);
+
 	if (!sugov_should_update_freq(sg_policy, time))
 		return;
 
@@ -356,6 +368,8 @@ sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
 	sugov_set_iowait_boost(sg_cpu, time, flags);
 	sg_cpu->last_update = time;
 
+	ignore_dl_rate_limit(sg_cpu, sg_policy);
+
 	if (sugov_should_update_freq(sg_policy, time)) {
 		next_f = sugov_next_freq_shared(sg_cpu, time);
 		sugov_update_commit(sg_policy, time, next_f);