Received-SPF: pass (google.com: domain of linux-kernel+bounces-21125-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
From: Vincent Guittot <vincent.guittot@linaro.org>
To: linux@armlinux.org.uk,
	catalin.marinas@arm.com,
	will@kernel.org,
	sudeep.holla@arm.com,
	rafael@kernel.org,
	viresh.kumar@linaro.org,
	agross@kernel.org,
	andersson@kernel.org,
	konrad.dybcio@linaro.org,
	mingo@redhat.com,
	peterz@infradead.org,
	juri.lelli@redhat.com,
	dietmar.eggemann@arm.com,
	rostedt@goodmis.org,
	bsegall@google.com,
	mgorman@suse.de,
	bristot@redhat.com,
	vschneid@redhat.com,
	lukasz.luba@arm.com,
	rui.zhang@intel.com,
	mhiramat@kernel.org,
	daniel.lezcano@linaro.org,
	amit.kachhap@gmail.com,
	corbet@lwn.net,
	gregkh@linuxfoundation.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org,
	linux-arm-msm@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org
Cc: qyousef@layalina.io,
	Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH v4 1/5] cpufreq: Add a cpufreq pressure feedback for the scheduler
Date: Tue,  9 Jan 2024 17:46:51 +0100
Message-Id: <20240109164655.626085-2-vincent.guittot@linaro.org>
In-Reply-To: <20240109164655.626085-1-vincent.guittot@linaro.org>
References: <20240109164655.626085-1-vincent.guittot@linaro.org>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Provide to the scheduler a feedback about the temporary max available
capacity. Unlike arch_update_thermal_pressure, this doesn't need to be
filtered as the pressure will happen for dozens ms or more.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 36 ++++++++++++++++++++++++++++++++++++
 include/linux/cpufreq.h   | 10 ++++++++++
 2 files changed, 46 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 44db4f59c4cc..f4eee3d107f1 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2563,6 +2563,40 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
 }
 EXPORT_SYMBOL(cpufreq_get_policy);
 
+DEFINE_PER_CPU(unsigned long, cpufreq_pressure);
+
+/**
+ * cpufreq_update_pressure() - Update cpufreq pressure for CPUs
+ * @policy: cpufreq policy of the CPUs.
+ *
+ * Update the value of cpufreq pressure for all @cpus in the policy.
+ */
+static void cpufreq_update_pressure(struct cpufreq_policy *policy)
+{
+	unsigned long max_capacity, capped_freq, pressure;
+	u32 max_freq;
+	int cpu;
+
+	cpu = cpumask_first(policy->related_cpus);
+	max_freq = arch_scale_freq_ref(cpu);
+	capped_freq = policy->max;
+
+	/*
+	 * Handle properly the boost frequencies, which should simply clean
+	 * the cpufreq pressure value.
+	 */
+	if (max_freq <= capped_freq) {
+		pressure = 0;
+	} else {
+		max_capacity = arch_scale_cpu_capacity(cpu);
+		pressure = max_capacity -
+			   mult_frac(max_capacity, capped_freq, max_freq);
+	}
+
+	for_each_cpu(cpu, policy->related_cpus)
+		WRITE_ONCE(per_cpu(cpufreq_pressure, cpu), pressure);
+}
+
 /**
  * cpufreq_set_policy - Modify cpufreq policy parameters.
  * @policy: Policy object to modify.
@@ -2618,6 +2652,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
 	policy->max = __resolve_freq(policy, policy->max, CPUFREQ_RELATION_H);
 	trace_cpu_frequency_limits(policy);
 
+	cpufreq_update_pressure(policy);
+
 	policy->cached_target_freq = UINT_MAX;
 
 	pr_debug("new min and max freqs are %u - %u kHz\n",
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index afda5f24d3dd..b1d97edd3253 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -241,6 +241,12 @@ struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy);
 void cpufreq_enable_fast_switch(struct cpufreq_policy *policy);
 void cpufreq_disable_fast_switch(struct cpufreq_policy *policy);
 bool has_target_index(void);
+
+DECLARE_PER_CPU(unsigned long, cpufreq_pressure);
+static inline unsigned long cpufreq_get_pressure(int cpu)
+{
+	return per_cpu(cpufreq_pressure, cpu);
+}
 #else
 static inline unsigned int cpufreq_get(unsigned int cpu)
 {
@@ -263,6 +269,10 @@ static inline bool cpufreq_supports_freq_invariance(void)
 	return false;
 }
 static inline void disable_cpufreq(void) { }
+static inline unsigned long cpufreq_get_pressure(int cpu)
+{
+	return 0;
+}
 #endif
 
 #ifdef CONFIG_CPU_FREQ_STAT
-- 
2.34.1