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Message-ID: <2d1d5cda-63c3-07a9-ae5f-abbc300ed1fc@linaro.org>
Date: Sat, 1 Jun 2019 12:37:06 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Quentin Perret <quentin.perret@....com>, edubezval@...il.com,
rui.zhang@...el.com, javi.merino@...nel.org,
viresh.kumar@...aro.org, amit.kachhap@...il.com, rjw@...ysocki.net,
will.deacon@....com, catalin.marinas@....com,
dietmar.eggemann@....com, ionela.voinescu@....com,
mka@...omium.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 3/3] thermal: cpu_cooling: Migrate to using the EM
framework
On 30/05/2019 11:20, Quentin Perret wrote:
> 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: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Quentin Perret <quentin.perret@....com>
Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
> 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);
>
--
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