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Message-Id: <1520937340-2755-1-git-send-email-claudio@evidence.eu.com>
Date: Tue, 13 Mar 2018 11:35:40 +0100
From: Claudio Scordino <claudio@...dence.eu.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>
Cc: Claudio Scordino <claudio@...dence.eu.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Viresh Kumar <viresh.kumar@...aro.org>,
Patrick Bellasi <patrick.bellasi@....com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Morten Rasmussen <morten.rasmussen@....com>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Todd Kjos <tkjos@...roid.com>,
Joel Fernandes <joelaf@...gle.com>, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v4] cpufreq: schedutil: rate limits for SCHED_DEADLINE
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@...dence.eu.com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
CC: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
CC: Viresh Kumar <viresh.kumar@...aro.org>
CC: Patrick Bellasi <patrick.bellasi@....com>
CC: Dietmar Eggemann <dietmar.eggemann@....com>
CC: Morten Rasmussen <morten.rasmussen@....com>
CC: Juri Lelli <juri.lelli@...hat.com>
CC: Vincent Guittot <vincent.guittot@...aro.org>
CC: Todd Kjos <tkjos@...roid.com>
CC: Joel Fernandes <joelaf@...gle.com>
CC: linux-pm@...r.kernel.org
CC: linux-kernel@...r.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
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