[RESEND][PATCH v8 4/8] PM / EM: add support for other devices than CPUs in Energy Model
Rafael J. Wysocki
rafael at kernel.org
Wed Jun 24 11:21:08 EDT 2020
On Wed, Jun 10, 2020 at 12:12 PM Lukasz Luba <lukasz.luba at arm.com> wrote:
>
> Add support for other devices than CPUs. The registration function
> does not require a valid cpumask pointer and is ready to handle new
> devices. Some of the internal structures has been reorganized in order to
> keep consistent view (like removing per_cpu pd pointers).
>
> Signed-off-by: Lukasz Luba <lukasz.luba at arm.com>
> ---
> Hi all,
>
> This is just a small change compared to v8 addressing Rafael's
> comments an Dan's static analyzes.
> Here are the changes:
> - added comment about mutex usage in the unregister function
> - changed 'dev' into @dev in the kerneldoc comments
> - removed 'else' statement from em_create_pd() to calm down static analizers
I've applied the series as 5.9 material with patch [4/8] replaced with this one.
Sorry for the delays in handling this!
Thanks!
> include/linux/device.h | 5 +
> include/linux/energy_model.h | 29 ++++-
> kernel/power/energy_model.c | 244 ++++++++++++++++++++++++-----------
> 3 files changed, 194 insertions(+), 84 deletions(-)
>
> diff --git a/include/linux/device.h b/include/linux/device.h
> index ac8e37cd716a..7023d3ea189b 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -13,6 +13,7 @@
> #define _DEVICE_H_
>
> #include <linux/dev_printk.h>
> +#include <linux/energy_model.h>
> #include <linux/ioport.h>
> #include <linux/kobject.h>
> #include <linux/klist.h>
> @@ -559,6 +560,10 @@ struct device {
> struct dev_pm_info power;
> struct dev_pm_domain *pm_domain;
>
> +#ifdef CONFIG_ENERGY_MODEL
> + struct em_perf_domain *em_pd;
> +#endif
> +
> #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
> struct irq_domain *msi_domain;
> #endif
> diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> index 7076cb22b247..2d4689964029 100644
> --- a/include/linux/energy_model.h
> +++ b/include/linux/energy_model.h
> @@ -12,8 +12,10 @@
>
> /**
> * em_perf_state - Performance state of a performance domain
> - * @frequency: The CPU frequency in KHz, for consistency with CPUFreq
> - * @power: The power consumed by 1 CPU at this level, in milli-watts
> + * @frequency: The frequency in KHz, for consistency with CPUFreq
> + * @power: The power consumed at this level, in milli-watts (by 1 CPU or
> + by a registered device). It can be a total power: static and
> + dynamic.
> * @cost: The cost coefficient associated with this level, used during
> * energy calculation. Equal to: power * max_frequency / frequency
> */
> @@ -27,12 +29,16 @@ struct em_perf_state {
> * em_perf_domain - Performance domain
> * @table: List of performance states, in ascending order
> * @nr_perf_states: Number of performance states
> - * @cpus: Cpumask covering the CPUs of the domain
> + * @cpus: Cpumask covering the CPUs of the domain. It's here
> + * for performance reasons to avoid potential cache
> + * misses during energy calculations in the scheduler
> + * and simplifies allocating/freeing that memory region.
> *
> - * A "performance domain" represents a group of CPUs whose performance is
> - * scaled together. All CPUs of a performance domain must have the same
> - * micro-architecture. Performance domains often have a 1-to-1 mapping with
> - * CPUFreq policies.
> + * In case of CPU device, a "performance domain" represents a group of CPUs
> + * whose performance is scaled together. All CPUs of a performance domain
> + * must have the same micro-architecture. Performance domains often have
> + * a 1-to-1 mapping with CPUFreq policies. In case of other devices the @cpus
> + * field is unused.
> */
> struct em_perf_domain {
> struct em_perf_state *table;
> @@ -71,10 +77,12 @@ struct em_data_callback {
> #define EM_DATA_CB(_active_power_cb) { .active_power = &_active_power_cb }
>
> struct em_perf_domain *em_cpu_get(int cpu);
> +struct em_perf_domain *em_pd_get(struct device *dev);
> int em_register_perf_domain(cpumask_t *span, unsigned int nr_states,
> struct em_data_callback *cb);
> int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
> struct em_data_callback *cb, cpumask_t *span);
> +void em_dev_unregister_perf_domain(struct device *dev);
>
> /**
> * em_pd_energy() - Estimates the energy consumed by the CPUs of a perf. domain
> @@ -184,10 +192,17 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
> {
> return -EINVAL;
> }
> +static inline void em_dev_unregister_perf_domain(struct device *dev)
> +{
> +}
> static inline struct em_perf_domain *em_cpu_get(int cpu)
> {
> return NULL;
> }
> +static inline struct em_perf_domain *em_pd_get(struct device *dev)
> +{
> + return NULL;
> +}
> static inline unsigned long em_pd_energy(struct em_perf_domain *pd,
> unsigned long max_util, unsigned long sum_util)
> {
> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> index 5b8a1566526a..32d76e78f992 100644
> --- a/kernel/power/energy_model.c
> +++ b/kernel/power/energy_model.c
> @@ -1,9 +1,10 @@
> // SPDX-License-Identifier: GPL-2.0
> /*
> - * Energy Model of CPUs
> + * Energy Model of devices
> *
> - * Copyright (c) 2018, Arm ltd.
> + * Copyright (c) 2018-2020, Arm ltd.
> * Written by: Quentin Perret, Arm ltd.
> + * Improvements provided by: Lukasz Luba, Arm ltd.
> */
>
> #define pr_fmt(fmt) "energy_model: " fmt
> @@ -15,15 +16,17 @@
> #include <linux/sched/topology.h>
> #include <linux/slab.h>
>
> -/* Mapping of each CPU to the performance domain to which it belongs. */
> -static DEFINE_PER_CPU(struct em_perf_domain *, em_data);
> -
> /*
> * Mutex serializing the registrations of performance domains and letting
> * callbacks defined by drivers sleep.
> */
> static DEFINE_MUTEX(em_pd_mutex);
>
> +static bool _is_cpu_device(struct device *dev)
> +{
> + return (dev->bus == &cpu_subsys);
> +}
> +
> #ifdef CONFIG_DEBUG_FS
> static struct dentry *rootdir;
>
> @@ -49,22 +52,30 @@ static int em_debug_cpus_show(struct seq_file *s, void *unused)
> }
> DEFINE_SHOW_ATTRIBUTE(em_debug_cpus);
>
> -static void em_debug_create_pd(struct em_perf_domain *pd, int cpu)
> +static void em_debug_create_pd(struct device *dev)
> {
> struct dentry *d;
> - char name[8];
> int i;
>
> - snprintf(name, sizeof(name), "pd%d", cpu);
> -
> /* Create the directory of the performance domain */
> - d = debugfs_create_dir(name, rootdir);
> + d = debugfs_create_dir(dev_name(dev), rootdir);
>
> - debugfs_create_file("cpus", 0444, d, pd->cpus, &em_debug_cpus_fops);
> + if (_is_cpu_device(dev))
> + debugfs_create_file("cpus", 0444, d, dev->em_pd->cpus,
> + &em_debug_cpus_fops);
>
> /* Create a sub-directory for each performance state */
> - for (i = 0; i < pd->nr_perf_states; i++)
> - em_debug_create_ps(&pd->table[i], d);
> + for (i = 0; i < dev->em_pd->nr_perf_states; i++)
> + em_debug_create_ps(&dev->em_pd->table[i], d);
> +
> +}
> +
> +static void em_debug_remove_pd(struct device *dev)
> +{
> + struct dentry *debug_dir;
> +
> + debug_dir = debugfs_lookup(dev_name(dev), rootdir);
> + debugfs_remove_recursive(debug_dir);
> }
>
> static int __init em_debug_init(void)
> @@ -76,40 +87,34 @@ static int __init em_debug_init(void)
> }
> core_initcall(em_debug_init);
> #else /* CONFIG_DEBUG_FS */
> -static void em_debug_create_pd(struct em_perf_domain *pd, int cpu) {}
> +static void em_debug_create_pd(struct device *dev) {}
> +static void em_debug_remove_pd(struct device *dev) {}
> #endif
> -static struct em_perf_domain *
> -em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb,
> - cpumask_t *span)
> +
> +static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
> + int nr_states, struct em_data_callback *cb)
> {
> unsigned long opp_eff, prev_opp_eff = ULONG_MAX;
> unsigned long power, freq, prev_freq = 0;
> - int i, ret, cpu = cpumask_first(span);
> struct em_perf_state *table;
> - struct em_perf_domain *pd;
> + int i, ret;
> u64 fmax;
>
> - if (!cb->active_power)
> - return NULL;
> -
> - pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL);
> - if (!pd)
> - return NULL;
> -
> table = kcalloc(nr_states, sizeof(*table), GFP_KERNEL);
> if (!table)
> - goto free_pd;
> + return -ENOMEM;
>
> /* Build the list of performance states for this performance domain */
> for (i = 0, freq = 0; i < nr_states; i++, freq++) {
> /*
> * active_power() is a driver callback which ceils 'freq' to
> - * lowest performance state of 'cpu' above 'freq' and updates
> + * lowest performance state of 'dev' above 'freq' and updates
> * 'power' and 'freq' accordingly.
> */
> ret = cb->active_power(&power, &freq, dev);
> if (ret) {
> - pr_err("pd%d: invalid perf. state: %d\n", cpu, ret);
> + dev_err(dev, "EM: invalid perf. state: %d\n",
> + ret);
> goto free_ps_table;
> }
>
> @@ -118,7 +123,8 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb,
> * higher performance states.
> */
> if (freq <= prev_freq) {
> - pr_err("pd%d: non-increasing freq: %lu\n", cpu, freq);
> + dev_err(dev, "EM: non-increasing freq: %lu\n",
> + freq);
> goto free_ps_table;
> }
>
> @@ -127,7 +133,8 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb,
> * positive, in milli-watts and to fit into 16 bits.
> */
> if (!power || power > EM_MAX_POWER) {
> - pr_err("pd%d: invalid power: %lu\n", cpu, power);
> + dev_err(dev, "EM: invalid power: %lu\n",
> + power);
> goto free_ps_table;
> }
>
> @@ -142,8 +149,8 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb,
> */
> opp_eff = freq / power;
> if (opp_eff >= prev_opp_eff)
> - pr_warn("pd%d: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
> - cpu, i, i - 1);
> + dev_dbg(dev, "EM: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
> + i, i - 1);
> prev_opp_eff = opp_eff;
> }
>
> @@ -156,30 +163,82 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb,
>
> pd->table = table;
> pd->nr_perf_states = nr_states;
> - cpumask_copy(to_cpumask(pd->cpus), span);
>
> - em_debug_create_pd(pd, cpu);
> -
> - return pd;
> + return 0;
>
> free_ps_table:
> kfree(table);
> -free_pd:
> - kfree(pd);
> + return -EINVAL;
> +}
> +
> +static int em_create_pd(struct device *dev, int nr_states,
> + struct em_data_callback *cb, cpumask_t *cpus)
> +{
> + struct em_perf_domain *pd;
> + struct device *cpu_dev;
> + int cpu, ret;
> +
> + if (_is_cpu_device(dev)) {
> + pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL);
> + if (!pd)
> + return -ENOMEM;
> +
> + cpumask_copy(em_span_cpus(pd), cpus);
> + } else {
> + pd = kzalloc(sizeof(*pd), GFP_KERNEL);
> + if (!pd)
> + return -ENOMEM;
> + }
> +
> + ret = em_create_perf_table(dev, pd, nr_states, cb);
> + if (ret) {
> + kfree(pd);
> + return ret;
> + }
> +
> + if (_is_cpu_device(dev))
> + for_each_cpu(cpu, cpus) {
> + cpu_dev = get_cpu_device(cpu);
> + cpu_dev->em_pd = pd;
> + }
> +
> + dev->em_pd = pd;
> +
> + return 0;
> +}
> +
> +/**
> + * em_pd_get() - Return the performance domain for a device
> + * @dev : Device to find the performance domain for
> + *
> + * Returns the performance domain to which @dev belongs, or NULL if it doesn't
> + * exist.
> + */
> +struct em_perf_domain *em_pd_get(struct device *dev)
> +{
> + if (IS_ERR_OR_NULL(dev))
> + return NULL;
>
> - return NULL;
> + return dev->em_pd;
> }
> +EXPORT_SYMBOL_GPL(em_pd_get);
>
> /**
> * em_cpu_get() - Return the performance domain for a CPU
> * @cpu : CPU to find the performance domain for
> *
> - * Return: the performance domain to which 'cpu' belongs, or NULL if it doesn't
> + * Returns the performance domain to which @cpu belongs, or NULL if it doesn't
> * exist.
> */
> struct em_perf_domain *em_cpu_get(int cpu)
> {
> - return READ_ONCE(per_cpu(em_data, cpu));
> + struct device *cpu_dev;
> +
> + cpu_dev = get_cpu_device(cpu);
> + if (!cpu_dev)
> + return NULL;
> +
> + return em_pd_get(cpu_dev);
> }
> EXPORT_SYMBOL_GPL(em_cpu_get);
>
> @@ -188,7 +247,7 @@ EXPORT_SYMBOL_GPL(em_cpu_get);
> * @dev : Device for which the EM is to register
> * @nr_states : Number of performance states to register
> * @cb : Callback functions providing the data of the Energy Model
> - * @span : Pointer to cpumask_t, which in case of a CPU device is
> + * @cpus : Pointer to cpumask_t, which in case of a CPU device is
> * obligatory. It can be taken from i.e. 'policy->cpus'. For other
> * type of devices this should be set to NULL.
> *
> @@ -201,13 +260,12 @@ EXPORT_SYMBOL_GPL(em_cpu_get);
> * Return 0 on success
> */
> int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
> - struct em_data_callback *cb, cpumask_t *span)
> + struct em_data_callback *cb, cpumask_t *cpus)
> {
> unsigned long cap, prev_cap = 0;
> - struct em_perf_domain *pd;
> - int cpu, ret = 0;
> + int cpu, ret;
>
> - if (!dev || !span || !nr_states || !cb)
> + if (!dev || !nr_states || !cb)
> return -EINVAL;
>
> /*
> @@ -216,47 +274,50 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
> */
> mutex_lock(&em_pd_mutex);
>
> - for_each_cpu(cpu, span) {
> - /* Make sure we don't register again an existing domain. */
> - if (READ_ONCE(per_cpu(em_data, cpu))) {
> - ret = -EEXIST;
> - goto unlock;
> - }
> + if (dev->em_pd) {
> + ret = -EEXIST;
> + goto unlock;
> + }
>
> - /*
> - * All CPUs of a domain must have the same micro-architecture
> - * since they all share the same table.
> - */
> - cap = arch_scale_cpu_capacity(cpu);
> - if (prev_cap && prev_cap != cap) {
> - pr_err("CPUs of %*pbl must have the same capacity\n",
> - cpumask_pr_args(span));
> + if (_is_cpu_device(dev)) {
> + if (!cpus) {
> + dev_err(dev, "EM: invalid CPU mask\n");
> ret = -EINVAL;
> goto unlock;
> }
> - prev_cap = cap;
> +
> + for_each_cpu(cpu, cpus) {
> + if (em_cpu_get(cpu)) {
> + dev_err(dev, "EM: exists for CPU%d\n", cpu);
> + ret = -EEXIST;
> + goto unlock;
> + }
> + /*
> + * All CPUs of a domain must have the same
> + * micro-architecture since they all share the same
> + * table.
> + */
> + cap = arch_scale_cpu_capacity(cpu);
> + if (prev_cap && prev_cap != cap) {
> + dev_err(dev, "EM: CPUs of %*pbl must have the same capacity\n",
> + cpumask_pr_args(cpus));
> +
> + ret = -EINVAL;
> + goto unlock;
> + }
> + prev_cap = cap;
> + }
> }
>
> - /* Create the performance domain and add it to the Energy Model. */
> - pd = em_create_pd(dev, nr_states, cb, span);
> - if (!pd) {
> - ret = -EINVAL;
> + ret = em_create_pd(dev, nr_states, cb, cpus);
> + if (ret)
> goto unlock;
> - }
>
> - for_each_cpu(cpu, span) {
> - /*
> - * The per-cpu array can be read concurrently from em_cpu_get().
> - * The barrier enforces the ordering needed to make sure readers
> - * can only access well formed em_perf_domain structs.
> - */
> - smp_store_release(per_cpu_ptr(&em_data, cpu), pd);
> - }
> + em_debug_create_pd(dev);
> + dev_info(dev, "EM: created perf domain\n");
>
> - pr_debug("Created perf domain %*pbl\n", cpumask_pr_args(span));
> unlock:
> mutex_unlock(&em_pd_mutex);
> -
> return ret;
> }
> EXPORT_SYMBOL_GPL(em_dev_register_perf_domain);
> @@ -285,3 +346,32 @@ int em_register_perf_domain(cpumask_t *span, unsigned int nr_states,
> return em_dev_register_perf_domain(cpu_dev, nr_states, cb, span);
> }
> EXPORT_SYMBOL_GPL(em_register_perf_domain);
> +
> +/**
> + * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for a device
> + * @dev : Device for which the EM is registered
> + *
> + * Unregister the EM for the specified @dev (but not a CPU device).
> + */
> +void em_dev_unregister_perf_domain(struct device *dev)
> +{
> + if (IS_ERR_OR_NULL(dev) || !dev->em_pd)
> + return;
> +
> + if (_is_cpu_device(dev))
> + return;
> +
> + /*
> + * The mutex separates all register/unregister requests and protects
> + * from potential clean-up/setup issues in the debugfs directories.
> + * The debugfs directory name is the same as device's name.
> + */
> + mutex_lock(&em_pd_mutex);
> + em_debug_remove_pd(dev);
> +
> + kfree(dev->em_pd->table);
> + kfree(dev->em_pd);
> + dev->em_pd = NULL;
> + mutex_unlock(&em_pd_mutex);
> +}
> +EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);
> --
> 2.17.1
>
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