[PATCH v6 0/3] Make IPA use PM_EM

[PATCH v6 0/3] Make IPA use PM_EM

[Quentin Perret]

Changes in v6
*************
 - Added Daniel's and Viresh's Acked-by to all patches

Changes in v5:
**************
 - Changed patch 02 to guard IPA-specific code in cpu_cooling.c with
   appropriate ifdefery (Daniel)
 - Rebased on 5.2-rc2

Changes in v4:
**************
 - Added Viresh's Acked-by to all 3 patches
 - Improved commit message of patch 3/3 to explain how it has no
   functional impact on existing users (Eduardo)

Changes in v3:
**************
 - Changed warning message for unordered tables to something more
   explicit (Viresh)
 - Changed WARN() into a pr_err() for consistency

Changes in v2:
**************
 - Fixed patch 01/03 to actually enable CONFIG_ENERGY_MODEL
 - Added "depends on ENERGY_MODEL" to IPA (Daniel)
 - Added check to bail out if the freq table is unsorted (Viresh)

Cover letter:
*************

The Intelligent Power Allocator (IPA) thermal governor uses an Energy
Model (or EM) of the CPUs to re-distribute the power budget. To do so,
it builds a table of <frequency, power> tuples where the power values
are computed using the 'dynamic-power-coefficient' DT property. All of
this is done in and only for the thermal subsystem, and more
specifically for CPUs -- the power of other types of devices is obtained
differently.

Recently, the CPU scheduler has seen the introduction of Energy Aware
Scheduling (EAS) patches, which also rely on an EM of the CPUs. This EM,
however, is managed by an independent framework, called PM_EM, aimed to
be used by all kernel subsystems interested in the power consumed by
CPUs, and not only the scheduler.

This patch series follows this logic and removes the (now redundant)
thermal-specific EM computation code to migrate IPA to use PM_EM
instead.

Doing so should have no visible functional impact for existing users of
IPA since:

 - during the 5.1 development cycle, a series of patches [1] introduced
   in PM_OPP some infrastructure (dev_pm_opp_of_register_em()) enabling
   the registration of EMs in PM_EM using the DT property used by IPA;

 - the existing upstream cpufreq drivers marked with the
   'CPUFREQ_IS_COOLING_DEV' flag all call dev_pm_opp_of_register_em(),
   which means they all support PM_EM (the only two exceptions are
   qoriq-cpufreq which doesn't in fact use an EM and scmi-cpufreq which
   already supports PM_EM without using the PM_OPP infrastructurei
   because it read power costs directly from firmware);

So, migrating IPA to using PM_EM should effectively be just plumbing
since for the existing IPA users the PM_EM tables will contain the
exact same power values that IPA used to compute on its own until now.
The only new dependency is to compile in CONFIG_ENERGY_MODEL.

Why is this migration still a good thing ? For three main reasons.

 1. it removes redundant code;

 2. it introduces an abstraction layer between IPA and the EM
    computation. PM_EM offers to EAS and IPA (and potentially other
    clients) standardized EM tables and hides 'how' these tables have
    been obtained. PM_EM as of now supports power values either coming
    from the 'dynamic-power-coefficient' DT property or obtained
    directly from firmware using SCMI. The latter is a new feature for
    IPA and that comes 'for free' with the migration. This will also be
    true in the future every time PM_EM gets support for other ways of
    loading the EM. Moreover, PM_EM is documented and has a debugfs
    interface which should help adding support for new platforms.

 3. it builds a consistent view of the EM of CPUs across kernel
    subsystems, which is a pre-requisite for any kind of future work
    aiming at a smarter power allocation using scheduler knowledge about
    the system for example.

[1] https://lore.kernel.org/lkml/20190204110952.16025-1-quentin.perret@arm.com/


Quentin Perret (3):
  arm64: defconfig: Enable CONFIG_ENERGY_MODEL
  thermal: cpu_cooling: Make the power-related code depend on IPA
  thermal: cpu_cooling: Migrate to using the EM framework

 arch/arm64/configs/defconfig  |   1 +
 drivers/thermal/Kconfig       |   1 +
 drivers/thermal/cpu_cooling.c | 428 ++++++++++++++--------------------
 3 files changed, 178 insertions(+), 252 deletions(-)

-- 
2.22.0

[PATCH v6 1/3] arm64: defconfig: Enable CONFIG_ENERGY_MODEL

[Quentin Perret]

The recently introduced Energy Model (EM) framework manages power cost
tables for the CPUs of the system. Its only user right now is the
scheduler, in the context of Energy Aware Scheduling (EAS).

However, the EM framework also offers a generic infrastructure that
could replace subsystem-specific implementations of the same concepts,
as this is the case in the thermal framework.

So, in order to prepare the migration of the thermal subsystem to use
the EM framework, enable it in the default arm64 defconfig, which is the
most commonly used architecture for IPA. This will also compile-in all
of the EAS code, although it won't be enabled by default -- EAS requires
to use the 'schedutil' CPUFreq governor while arm64 defaults to
'performance'.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
---
 arch/arm64/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index 0e58ef02880c..ad0e4944a71f 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -71,6 +71,7 @@ CONFIG_COMPAT=y
 CONFIG_RANDOMIZE_BASE=y
 CONFIG_HIBERNATION=y
 CONFIG_WQ_POWER_EFFICIENT_DEFAULT=y
+CONFIG_ENERGY_MODEL=y
 CONFIG_ARM_CPUIDLE=y
 CONFIG_CPU_FREQ=y
 CONFIG_CPU_FREQ_STAT=y
-- 
2.22.0

[PATCH v6 2/3] thermal: cpu_cooling: Make the power-related code depend on IPA

[Quentin Perret]

The core CPU cooling infrastructure has power-related functions
that have only one client: IPA. Since there can be no user of those
functions if IPA is not compiled in, make sure to guard them with
checks on CONFIG_THERMAL_GOV_POWER_ALLOCATOR to not waste space
unnecessarily.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
---
 drivers/thermal/cpu_cooling.c | 214 +++++++++++++++++-----------------
 1 file changed, 104 insertions(+), 110 deletions(-)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 4c5db59a619b..498f59ab64b2 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -46,7 +46,9 @@
  */
 struct freq_table {
 	u32 frequency;
+#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 	u32 power;
+#endif
 };
 
 /**
@@ -96,28 +98,6 @@ static DEFINE_IDA(cpufreq_ida);
 static DEFINE_MUTEX(cooling_list_lock);
 static LIST_HEAD(cpufreq_cdev_list);
 
-/* Below code defines functions to be used for cpufreq as cooling device */
-
-/**
- * get_level: Find the level for a particular frequency
- * @cpufreq_cdev: cpufreq_cdev for which the property is required
- * @freq: Frequency
- *
- * Return: level corresponding to the frequency.
- */
-static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
-			       unsigned int freq)
-{
-	struct freq_table *freq_table = cpufreq_cdev->freq_table;
-	unsigned long level;
-
-	for (level = 1; level <= cpufreq_cdev->max_level; level++)
-		if (freq > freq_table[level].frequency)
-			break;
-
-	return level - 1;
-}
-
 /**
  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
  * @nb:	struct notifier_block * with callback info.
@@ -171,6 +151,27 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
+#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
+/**
+ * get_level: Find the level for a particular frequency
+ * @cpufreq_cdev: cpufreq_cdev for which the property is required
+ * @freq: Frequency
+ *
+ * Return: level corresponding to the frequency.
+ */
+static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
+			       unsigned int freq)
+{
+	struct freq_table *freq_table = cpufreq_cdev->freq_table;
+	unsigned long level;
+
+	for (level = 1; level <= cpufreq_cdev->max_level; level++)
+		if (freq > freq_table[level].frequency)
+			break;
+
+	return level - 1;
+}
+
 /**
  * update_freq_table() - Update the freq table with power numbers
  * @cpufreq_cdev:	the cpufreq cooling device in which to update the table
@@ -319,80 +320,6 @@ static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_cdev,
 	return (raw_cpu_power * cpufreq_cdev->last_load) / 100;
 }
 
-/* cpufreq cooling device callback functions are defined below */
-
-/**
- * cpufreq_get_max_state - callback function to get the max cooling state.
- * @cdev: thermal cooling device pointer.
- * @state: fill this variable with the max cooling state.
- *
- * Callback for the thermal cooling device to return the cpufreq
- * max cooling state.
- *
- * Return: 0 on success, an error code otherwise.
- */
-static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
-				 unsigned long *state)
-{
-	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
-
-	*state = cpufreq_cdev->max_level;
-	return 0;
-}
-
-/**
- * cpufreq_get_cur_state - callback function to get the current cooling state.
- * @cdev: thermal cooling device pointer.
- * @state: fill this variable with the current cooling state.
- *
- * Callback for the thermal cooling device to return the cpufreq
- * current cooling state.
- *
- * Return: 0 on success, an error code otherwise.
- */
-static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
-				 unsigned long *state)
-{
-	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
-
-	*state = cpufreq_cdev->cpufreq_state;
-
-	return 0;
-}
-
-/**
- * cpufreq_set_cur_state - callback function to set the current cooling state.
- * @cdev: thermal cooling device pointer.
- * @state: set this variable to the current cooling state.
- *
- * Callback for the thermal cooling device to change the cpufreq
- * current cooling state.
- *
- * Return: 0 on success, an error code otherwise.
- */
-static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
-				 unsigned long state)
-{
-	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
-	unsigned int clip_freq;
-
-	/* Request state should be less than max_level */
-	if (WARN_ON(state > cpufreq_cdev->max_level))
-		return -EINVAL;
-
-	/* Check if the old cooling action is same as new cooling action */
-	if (cpufreq_cdev->cpufreq_state == state)
-		return 0;
-
-	clip_freq = cpufreq_cdev->freq_table[state].frequency;
-	cpufreq_cdev->cpufreq_state = state;
-	cpufreq_cdev->clipped_freq = clip_freq;
-
-	cpufreq_update_policy(cpufreq_cdev->policy->cpu);
-
-	return 0;
-}
-
 /**
  * cpufreq_get_requested_power() - get the current power
  * @cdev:	&thermal_cooling_device pointer
@@ -536,22 +463,88 @@ static int cpufreq_power2state(struct thermal_cooling_device *cdev,
 				      power);
 	return 0;
 }
+#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
+
+/* cpufreq cooling device callback functions are defined below */
+
+/**
+ * cpufreq_get_max_state - callback function to get the max cooling state.
+ * @cdev: thermal cooling device pointer.
+ * @state: fill this variable with the max cooling state.
+ *
+ * Callback for the thermal cooling device to return the cpufreq
+ * max cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
+
+	*state = cpufreq_cdev->max_level;
+	return 0;
+}
+
+/**
+ * cpufreq_get_cur_state - callback function to get the current cooling state.
+ * @cdev: thermal cooling device pointer.
+ * @state: fill this variable with the current cooling state.
+ *
+ * Callback for the thermal cooling device to return the cpufreq
+ * current cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
+
+	*state = cpufreq_cdev->cpufreq_state;
+
+	return 0;
+}
+
+/**
+ * cpufreq_set_cur_state - callback function to set the current cooling state.
+ * @cdev: thermal cooling device pointer.
+ * @state: set this variable to the current cooling state.
+ *
+ * Callback for the thermal cooling device to change the cpufreq
+ * current cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long state)
+{
+	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
+	unsigned int clip_freq;
+
+	/* Request state should be less than max_level */
+	if (WARN_ON(state > cpufreq_cdev->max_level))
+		return -EINVAL;
+
+	/* Check if the old cooling action is same as new cooling action */
+	if (cpufreq_cdev->cpufreq_state == state)
+		return 0;
+
+	clip_freq = cpufreq_cdev->freq_table[state].frequency;
+	cpufreq_cdev->cpufreq_state = state;
+	cpufreq_cdev->clipped_freq = clip_freq;
+
+	cpufreq_update_policy(cpufreq_cdev->policy->cpu);
+
+	return 0;
+}
 
 /* Bind cpufreq callbacks to thermal cooling device ops */
 
 static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
-	.get_max_state = cpufreq_get_max_state,
-	.get_cur_state = cpufreq_get_cur_state,
-	.set_cur_state = cpufreq_set_cur_state,
-};
-
-static struct thermal_cooling_device_ops cpufreq_power_cooling_ops = {
 	.get_max_state		= cpufreq_get_max_state,
 	.get_cur_state		= cpufreq_get_cur_state,
 	.set_cur_state		= cpufreq_set_cur_state,
-	.get_requested_power	= cpufreq_get_requested_power,
-	.state2power		= cpufreq_state2power,
-	.power2state		= cpufreq_power2state,
 };
 
 /* Notifier for cpufreq policy change */
@@ -659,18 +652,19 @@ __cpufreq_cooling_register(struct device_node *np,
 			pr_debug("%s: freq:%u KHz\n", __func__, freq);
 	}
 
+	cooling_ops = &cpufreq_cooling_ops;
+#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 	if (capacitance) {
 		ret = update_freq_table(cpufreq_cdev, capacitance);
 		if (ret) {
 			cdev = ERR_PTR(ret);
 			goto remove_ida;
 		}
-
-		cooling_ops = &cpufreq_power_cooling_ops;
-	} else {
-		cooling_ops = &cpufreq_cooling_ops;
+		cooling_ops->get_requested_power = cpufreq_get_requested_power;
+		cooling_ops->state2power = cpufreq_state2power;
+		cooling_ops->power2state = cpufreq_power2state;
 	}
-
+#endif
 	cdev = thermal_of_cooling_device_register(np, dev_name, cpufreq_cdev,
 						  cooling_ops);
 	if (IS_ERR(cdev))
-- 
2.22.0

[PATCH v6 3/3] thermal: cpu_cooling: Migrate to using the EM framework

[Quentin Perret]

The newly introduced Energy Model framework manages power cost tables in
a generic way. Moreover, it supports several types of models since the
tables can come from DT or firmware (through SCMI) for example. On the
other hand, the cpu_cooling subsystem manages its own power cost tables
using only DT data.

In order to avoid the duplication of data in the kernel, and in order to
enable IPA with EMs coming from more than just DT, remove the private
tables from cpu_cooling.c and migrate it to using the centralized EM
framework. Doing so should have no visible functional impact for
existing users of IPA since:

 - recent extenstions to the the PM_OPP infrastructure enable the
   registration of EMs in PM_EM using the DT property used by IPA;

 - the existing upstream cpufreq drivers marked with the
   'CPUFREQ_IS_COOLING_DEV' flag all use the aforementioned PM_OPP
   infrastructure, which means they all support PM_EM. The only two
   exceptions are qoriq-cpufreq which doesn't in fact use an EM and
   scmi-cpufreq which doesn't use DT for power costs.

For existing users of cpu_cooling, PM_EM tables will contain the exact
same power values that IPA used to compute on its own until now. The
only new dependency for them is to compile in CONFIG_ENERGY_MODEL.

The case where the thermal subsystem is used without an Energy Model
(cpufreq_cooling_ops) is handled by looking directly at CPUFreq's
frequency table which is already a dependency for cpu_cooling.c anyway.
Since the thermal framework expects the cooling states in a particular
order, bail out whenever the CPUFreq table is unsorted, since that is
fairly uncommon in general, and there are currently no users of
cpu_cooling for this use-case.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
---
 drivers/thermal/Kconfig       |   1 +
 drivers/thermal/cpu_cooling.c | 250 ++++++++++++----------------------
 2 files changed, 91 insertions(+), 160 deletions(-)

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 9966364a6deb..340853a3ca48 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -144,6 +144,7 @@ config THERMAL_GOV_USER_SPACE
 
 config THERMAL_GOV_POWER_ALLOCATOR
 	bool "Power allocator thermal governor"
+	depends on ENERGY_MODEL
 	help
 	  Enable this to manage platform thermals by dynamically
 	  allocating and limiting power to devices.
diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 498f59ab64b2..83486775e593 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -19,6 +19,7 @@
 #include <linux/slab.h>
 #include <linux/cpu.h>
 #include <linux/cpu_cooling.h>
+#include <linux/energy_model.h>
 
 #include <trace/events/thermal.h>
 
@@ -36,21 +37,6 @@
  *	...
  */
 
-/**
- * struct freq_table - frequency table along with power entries
- * @frequency:	frequency in KHz
- * @power:	power in mW
- *
- * This structure is built when the cooling device registers and helps
- * in translating frequency to power and vice versa.
- */
-struct freq_table {
-	u32 frequency;
-#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
-	u32 power;
-#endif
-};
-
 /**
  * struct time_in_idle - Idle time stats
  * @time: previous reading of the absolute time that this cpu was idle
@@ -72,7 +58,7 @@ struct time_in_idle {
  *	frequency.
  * @max_level: maximum cooling level. One less than total number of valid
  *	cpufreq frequencies.
- * @freq_table: Freq table in descending order of frequencies
+ * @em: Reference on the Energy Model of the device
  * @cdev: thermal_cooling_device pointer to keep track of the
  *	registered cooling device.
  * @policy: cpufreq policy.
@@ -88,7 +74,7 @@ struct cpufreq_cooling_device {
 	unsigned int cpufreq_state;
 	unsigned int clipped_freq;
 	unsigned int max_level;
-	struct freq_table *freq_table;	/* In descending order */
+	struct em_perf_domain *em;
 	struct cpufreq_policy *policy;
 	struct list_head node;
 	struct time_in_idle *idle_time;
@@ -162,114 +148,40 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
 static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
 			       unsigned int freq)
 {
-	struct freq_table *freq_table = cpufreq_cdev->freq_table;
-	unsigned long level;
+	int i;
 
-	for (level = 1; level <= cpufreq_cdev->max_level; level++)
-		if (freq > freq_table[level].frequency)
+	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
+		if (freq > cpufreq_cdev->em->table[i].frequency)
 			break;
-
-	return level - 1;
-}
-
-/**
- * update_freq_table() - Update the freq table with power numbers
- * @cpufreq_cdev:	the cpufreq cooling device in which to update the table
- * @capacitance: dynamic power coefficient for these cpus
- *
- * Update the freq table with power numbers.  This table will be used in
- * cpu_power_to_freq() and cpu_freq_to_power() to convert between power and
- * frequency efficiently.  Power is stored in mW, frequency in KHz.  The
- * resulting table is in descending order.
- *
- * Return: 0 on success, -EINVAL if there are no OPPs for any CPUs,
- * or -ENOMEM if we run out of memory.
- */
-static int update_freq_table(struct cpufreq_cooling_device *cpufreq_cdev,
-			     u32 capacitance)
-{
-	struct freq_table *freq_table = cpufreq_cdev->freq_table;
-	struct dev_pm_opp *opp;
-	struct device *dev = NULL;
-	int num_opps = 0, cpu = cpufreq_cdev->policy->cpu, i;
-
-	dev = get_cpu_device(cpu);
-	if (unlikely(!dev)) {
-		pr_warn("No cpu device for cpu %d\n", cpu);
-		return -ENODEV;
-	}
-
-	num_opps = dev_pm_opp_get_opp_count(dev);
-	if (num_opps < 0)
-		return num_opps;
-
-	/*
-	 * The cpufreq table is also built from the OPP table and so the count
-	 * should match.
-	 */
-	if (num_opps != cpufreq_cdev->max_level + 1) {
-		dev_warn(dev, "Number of OPPs not matching with max_levels\n");
-		return -EINVAL;
-	}
-
-	for (i = 0; i <= cpufreq_cdev->max_level; i++) {
-		unsigned long freq = freq_table[i].frequency * 1000;
-		u32 freq_mhz = freq_table[i].frequency / 1000;
-		u64 power;
-		u32 voltage_mv;
-
-		/*
-		 * Find ceil frequency as 'freq' may be slightly lower than OPP
-		 * freq due to truncation while converting to kHz.
-		 */
-		opp = dev_pm_opp_find_freq_ceil(dev, &freq);
-		if (IS_ERR(opp)) {
-			dev_err(dev, "failed to get opp for %lu frequency\n",
-				freq);
-			return -EINVAL;
-		}
-
-		voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
-		dev_pm_opp_put(opp);
-
-		/*
-		 * Do the multiplication with MHz and millivolt so as
-		 * to not overflow.
-		 */
-		power = (u64)capacitance * freq_mhz * voltage_mv * voltage_mv;
-		do_div(power, 1000000000);
-
-		/* power is stored in mW */
-		freq_table[i].power = power;
 	}
 
-	return 0;
+	return cpufreq_cdev->max_level - i - 1;
 }
 
 static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
 			     u32 freq)
 {
 	int i;
-	struct freq_table *freq_table = cpufreq_cdev->freq_table;
 
-	for (i = 1; i <= cpufreq_cdev->max_level; i++)
-		if (freq > freq_table[i].frequency)
+	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
+		if (freq > cpufreq_cdev->em->table[i].frequency)
 			break;
+	}
 
-	return freq_table[i - 1].power;
+	return cpufreq_cdev->em->table[i + 1].power;
 }
 
 static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
 			     u32 power)
 {
 	int i;
-	struct freq_table *freq_table = cpufreq_cdev->freq_table;
 
-	for (i = 1; i <= cpufreq_cdev->max_level; i++)
-		if (power > freq_table[i].power)
+	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
+		if (power > cpufreq_cdev->em->table[i].power)
 			break;
+	}
 
-	return freq_table[i - 1].frequency;
+	return cpufreq_cdev->em->table[i + 1].frequency;
 }
 
 /**
@@ -410,7 +322,7 @@ static int cpufreq_state2power(struct thermal_cooling_device *cdev,
 			       struct thermal_zone_device *tz,
 			       unsigned long state, u32 *power)
 {
-	unsigned int freq, num_cpus;
+	unsigned int freq, num_cpus, idx;
 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 
 	/* Request state should be less than max_level */
@@ -419,7 +331,8 @@ static int cpufreq_state2power(struct thermal_cooling_device *cdev,
 
 	num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);
 
-	freq = cpufreq_cdev->freq_table[state].frequency;
+	idx = cpufreq_cdev->max_level - state;
+	freq = cpufreq_cdev->em->table[idx].frequency;
 	*power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;
 
 	return 0;
@@ -463,8 +376,60 @@ static int cpufreq_power2state(struct thermal_cooling_device *cdev,
 				      power);
 	return 0;
 }
+
+static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
+			      struct em_perf_domain *em) {
+	struct cpufreq_policy *policy;
+	unsigned int nr_levels;
+
+	if (!em)
+		return false;
+
+	policy = cpufreq_cdev->policy;
+	if (!cpumask_equal(policy->related_cpus, to_cpumask(em->cpus))) {
+		pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
+			cpumask_pr_args(to_cpumask(em->cpus)),
+			cpumask_pr_args(policy->related_cpus));
+		return false;
+	}
+
+	nr_levels = cpufreq_cdev->max_level + 1;
+	if (em->nr_cap_states != nr_levels) {
+		pr_err("The number of cap states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
+			cpumask_pr_args(to_cpumask(em->cpus)),
+			em->nr_cap_states, nr_levels);
+		return false;
+	}
+
+	return true;
+}
 #endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
 
+static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
+                             unsigned long state)
+{
+       struct cpufreq_policy *policy;
+       unsigned long idx;
+
+#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
+       /* Use the Energy Model table if available */
+       if (cpufreq_cdev->em) {
+               idx = cpufreq_cdev->max_level - state;
+               return cpufreq_cdev->em->table[idx].frequency;
+       }
+#endif
+
+       /* Otherwise, fallback on the CPUFreq table */
+       policy = cpufreq_cdev->policy;
+       if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
+               idx = cpufreq_cdev->max_level - state;
+       else
+               idx = state;
+
+       return policy->freq_table[idx].frequency;
+}
+
+
 /* cpufreq cooling device callback functions are defined below */
 
 /**
@@ -530,7 +495,7 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 	if (cpufreq_cdev->cpufreq_state == state)
 		return 0;
 
-	clip_freq = cpufreq_cdev->freq_table[state].frequency;
+	clip_freq = get_state_freq(cpufreq_cdev, state);
 	cpufreq_cdev->cpufreq_state = state;
 	cpufreq_cdev->clipped_freq = clip_freq;
 
@@ -552,26 +517,12 @@ static struct notifier_block thermal_cpufreq_notifier_block = {
 	.notifier_call = cpufreq_thermal_notifier,
 };
 
-static unsigned int find_next_max(struct cpufreq_frequency_table *table,
-				  unsigned int prev_max)
-{
-	struct cpufreq_frequency_table *pos;
-	unsigned int max = 0;
-
-	cpufreq_for_each_valid_entry(pos, table) {
-		if (pos->frequency > max && pos->frequency < prev_max)
-			max = pos->frequency;
-	}
-
-	return max;
-}
-
 /**
  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
  * @np: a valid struct device_node to the cooling device device tree node
  * @policy: cpufreq policy
  * Normally this should be same as cpufreq policy->related_cpus.
- * @capacitance: dynamic power coefficient for these cpus
+ * @em: Energy Model of the cpufreq policy
  *
  * This interface function registers the cpufreq cooling device with the name
  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
@@ -583,12 +534,13 @@ static unsigned int find_next_max(struct cpufreq_frequency_table *table,
  */
 static struct thermal_cooling_device *
 __cpufreq_cooling_register(struct device_node *np,
-			struct cpufreq_policy *policy, u32 capacitance)
+			struct cpufreq_policy *policy,
+			struct em_perf_domain *em)
 {
 	struct thermal_cooling_device *cdev;
 	struct cpufreq_cooling_device *cpufreq_cdev;
 	char dev_name[THERMAL_NAME_LENGTH];
-	unsigned int freq, i, num_cpus;
+	unsigned int i, num_cpus;
 	int ret;
 	struct thermal_cooling_device_ops *cooling_ops;
 	bool first;
@@ -622,55 +574,38 @@ __cpufreq_cooling_register(struct device_node *np,
 	/* max_level is an index, not a counter */
 	cpufreq_cdev->max_level = i - 1;
 
-	cpufreq_cdev->freq_table = kmalloc_array(i,
-					sizeof(*cpufreq_cdev->freq_table),
-					GFP_KERNEL);
-	if (!cpufreq_cdev->freq_table) {
-		cdev = ERR_PTR(-ENOMEM);
-		goto free_idle_time;
-	}
-
 	ret = ida_simple_get(&cpufreq_ida, 0, 0, GFP_KERNEL);
 	if (ret < 0) {
 		cdev = ERR_PTR(ret);
-		goto free_table;
+		goto free_idle_time;
 	}
 	cpufreq_cdev->id = ret;
 
 	snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
 		 cpufreq_cdev->id);
 
-	/* Fill freq-table in descending order of frequencies */
-	for (i = 0, freq = -1; i <= cpufreq_cdev->max_level; i++) {
-		freq = find_next_max(policy->freq_table, freq);
-		cpufreq_cdev->freq_table[i].frequency = freq;
-
-		/* Warn for duplicate entries */
-		if (!freq)
-			pr_warn("%s: table has duplicate entries\n", __func__);
-		else
-			pr_debug("%s: freq:%u KHz\n", __func__, freq);
-	}
-
 	cooling_ops = &cpufreq_cooling_ops;
 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
-	if (capacitance) {
-		ret = update_freq_table(cpufreq_cdev, capacitance);
-		if (ret) {
-			cdev = ERR_PTR(ret);
-			goto remove_ida;
-		}
+	if (em_is_sane(cpufreq_cdev, em)) {
+		cpufreq_cdev->em = em;
 		cooling_ops->get_requested_power = cpufreq_get_requested_power;
 		cooling_ops->state2power = cpufreq_state2power;
 		cooling_ops->power2state = cpufreq_power2state;
-	}
+	} else
 #endif
+	if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
+		pr_err("%s: unsorted frequency tables are not supported\n",
+				__func__);
+		cdev = ERR_PTR(-EINVAL);
+		goto remove_ida;
+	}
+
 	cdev = thermal_of_cooling_device_register(np, dev_name, cpufreq_cdev,
 						  cooling_ops);
 	if (IS_ERR(cdev))
 		goto remove_ida;
 
-	cpufreq_cdev->clipped_freq = cpufreq_cdev->freq_table[0].frequency;
+	cpufreq_cdev->clipped_freq = get_state_freq(cpufreq_cdev, 0);
 
 	mutex_lock(&cooling_list_lock);
 	/* Register the notifier for first cpufreq cooling device */
@@ -686,8 +621,6 @@ __cpufreq_cooling_register(struct device_node *np,
 
 remove_ida:
 	ida_simple_remove(&cpufreq_ida, cpufreq_cdev->id);
-free_table:
-	kfree(cpufreq_cdev->freq_table);
 free_idle_time:
 	kfree(cpufreq_cdev->idle_time);
 free_cdev:
@@ -709,7 +642,7 @@ __cpufreq_cooling_register(struct device_node *np,
 struct thermal_cooling_device *
 cpufreq_cooling_register(struct cpufreq_policy *policy)
 {
-	return __cpufreq_cooling_register(NULL, policy, 0);
+	return __cpufreq_cooling_register(NULL, policy, NULL);
 }
 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 
@@ -737,7 +670,6 @@ of_cpufreq_cooling_register(struct cpufreq_policy *policy)
 {
 	struct device_node *np = of_get_cpu_node(policy->cpu, NULL);
 	struct thermal_cooling_device *cdev = NULL;
-	u32 capacitance = 0;
 
 	if (!np) {
 		pr_err("cpu_cooling: OF node not available for cpu%d\n",
@@ -746,10 +678,9 @@ of_cpufreq_cooling_register(struct cpufreq_policy *policy)
 	}
 
 	if (of_find_property(np, "#cooling-cells", NULL)) {
-		of_property_read_u32(np, "dynamic-power-coefficient",
-				     &capacitance);
+		struct em_perf_domain *em = em_cpu_get(policy->cpu);
 
-		cdev = __cpufreq_cooling_register(np, policy, capacitance);
+		cdev = __cpufreq_cooling_register(np, policy, em);
 		if (IS_ERR(cdev)) {
 			pr_err("cpu_cooling: cpu%d failed to register as cooling device: %ld\n",
 			       policy->cpu, PTR_ERR(cdev));
@@ -791,7 +722,6 @@ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 	thermal_cooling_device_unregister(cdev);
 	ida_simple_remove(&cpufreq_ida, cpufreq_cdev->id);
 	kfree(cpufreq_cdev->idle_time);
-	kfree(cpufreq_cdev->freq_table);
 	kfree(cpufreq_cdev);
 }
 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);
-- 
2.22.0

Re: [PATCH v6 0/3] Make IPA use PM_EM

[Daniel Lezcano]

Hi Rui,

is it possible to merge these patches? They are acked-by since May.

Thanks

  -- Daniel


On 01/08/2019 14:46, Quentin Perret wrote:
> Changes in v6
> *************
>  - Added Daniel's and Viresh's Acked-by to all patches
> 
> Changes in v5:
> **************
>  - Changed patch 02 to guard IPA-specific code in cpu_cooling.c with
>    appropriate ifdefery (Daniel)
>  - Rebased on 5.2-rc2
> 
> Changes in v4:
> **************
>  - Added Viresh's Acked-by to all 3 patches
>  - Improved commit message of patch 3/3 to explain how it has no
>    functional impact on existing users (Eduardo)
> 
> Changes in v3:
> **************
>  - Changed warning message for unordered tables to something more
>    explicit (Viresh)
>  - Changed WARN() into a pr_err() for consistency
> 
> Changes in v2:
> **************
>  - Fixed patch 01/03 to actually enable CONFIG_ENERGY_MODEL
>  - Added "depends on ENERGY_MODEL" to IPA (Daniel)
>  - Added check to bail out if the freq table is unsorted (Viresh)
> 
> Cover letter:
> *************
> 
> The Intelligent Power Allocator (IPA) thermal governor uses an Energy
> Model (or EM) of the CPUs to re-distribute the power budget. To do so,
> it builds a table of <frequency, power> tuples where the power values
> are computed using the 'dynamic-power-coefficient' DT property. All of
> this is done in and only for the thermal subsystem, and more
> specifically for CPUs -- the power of other types of devices is obtained
> differently.
> 
> Recently, the CPU scheduler has seen the introduction of Energy Aware
> Scheduling (EAS) patches, which also rely on an EM of the CPUs. This EM,
> however, is managed by an independent framework, called PM_EM, aimed to
> be used by all kernel subsystems interested in the power consumed by
> CPUs, and not only the scheduler.
> 
> This patch series follows this logic and removes the (now redundant)
> thermal-specific EM computation code to migrate IPA to use PM_EM
> instead.
> 
> Doing so should have no visible functional impact for existing users of
> IPA since:
> 
>  - during the 5.1 development cycle, a series of patches [1] introduced
>    in PM_OPP some infrastructure (dev_pm_opp_of_register_em()) enabling
>    the registration of EMs in PM_EM using the DT property used by IPA;
> 
>  - the existing upstream cpufreq drivers marked with the
>    'CPUFREQ_IS_COOLING_DEV' flag all call dev_pm_opp_of_register_em(),
>    which means they all support PM_EM (the only two exceptions are
>    qoriq-cpufreq which doesn't in fact use an EM and scmi-cpufreq which
>    already supports PM_EM without using the PM_OPP infrastructurei
>    because it read power costs directly from firmware);
> 
> So, migrating IPA to using PM_EM should effectively be just plumbing
> since for the existing IPA users the PM_EM tables will contain the
> exact same power values that IPA used to compute on its own until now.
> The only new dependency is to compile in CONFIG_ENERGY_MODEL.
> 
> Why is this migration still a good thing ? For three main reasons.
> 
>  1. it removes redundant code;
> 
>  2. it introduces an abstraction layer between IPA and the EM
>     computation. PM_EM offers to EAS and IPA (and potentially other
>     clients) standardized EM tables and hides 'how' these tables have
>     been obtained. PM_EM as of now supports power values either coming
>     from the 'dynamic-power-coefficient' DT property or obtained
>     directly from firmware using SCMI. The latter is a new feature for
>     IPA and that comes 'for free' with the migration. This will also be
>     true in the future every time PM_EM gets support for other ways of
>     loading the EM. Moreover, PM_EM is documented and has a debugfs
>     interface which should help adding support for new platforms.
> 
>  3. it builds a consistent view of the EM of CPUs across kernel
>     subsystems, which is a pre-requisite for any kind of future work
>     aiming at a smarter power allocation using scheduler knowledge about
>     the system for example.
> 
> [1] https://lore.kernel.org/lkml/20190204110952.16025-1-quentin.perret@arm.com/
> 
> 
> Quentin Perret (3):
>   arm64: defconfig: Enable CONFIG_ENERGY_MODEL
>   thermal: cpu_cooling: Make the power-related code depend on IPA
>   thermal: cpu_cooling: Migrate to using the EM framework
> 
>  arch/arm64/configs/defconfig  |   1 +
>  drivers/thermal/Kconfig       |   1 +
>  drivers/thermal/cpu_cooling.c | 428 ++++++++++++++--------------------
>  3 files changed, 178 insertions(+), 252 deletions(-)
> 


-- 
 <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

Re: [PATCH v6 3/3] thermal: cpu_cooling: Migrate to using the EM framework

[Quentin Perret]

Hi all,

On Thursday 01 Aug 2019 at 13:46:43 (+0100), Quentin Perret wrote:
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 9966364a6deb..340853a3ca48 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -144,6 +144,7 @@ config THERMAL_GOV_USER_SPACE
>  
>  config THERMAL_GOV_POWER_ALLOCATOR
>  	bool "Power allocator thermal governor"
> +	depends on ENERGY_MODEL
>  	help
>  	  Enable this to manage platform thermals by dynamically
>  	  allocating and limiting power to devices.

FYI, the kbuild bot just reported a randconfig build issue with this.
THERMAL_DEFAULT_GOV_POWER_ALLOCATOR 'select' THERMAL_GOV_POWER_ALLOCATOR
unconditionally. And I just learned 'select' will force the option ON
and totally ignore its dependencies. That is, we can end up with IPA
force-compiled in, and no PM_EM, which is broken.

So I guess the simplest fix is to do 'select ENERGY_MODEL' in this
patch, instead of depending on it.

I'll send a v7 with this fixed shortly.

Thanks,
Quentin