// SPDX-License-Identifier: GPL-2.0-only
/*
* intel_powerclamp.c - package c-state idle injection
*
* Copyright (c) 2012-2023, Intel Corporation.
*
* Authors:
* Arjan van de Ven <[email protected]>
* Jacob Pan <[email protected]>
*
* TODO:
* 1. better handle wakeup from external interrupts, currently a fixed
* compensation is added to clamping duration when excessive amount
* of wakeups are observed during idle time. the reason is that in
* case of external interrupts without need for ack, clamping down
* cpu in non-irq context does not reduce irq. for majority of the
* cases, clamping down cpu does help reduce irq as well, we should
* be able to differentiate the two cases and give a quantitative
* solution for the irqs that we can control. perhaps based on
* get_cpu_iowait_time_us()
*
* 2. synchronization with other hw blocks
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/thermal.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/idle_inject.h>
#include <asm/msr.h>
#include <asm/mwait.h>
#include <asm/cpu_device_id.h>
#define MAX_TARGET_RATIO (100U)
/* For each undisturbed clamping period (no extra wake ups during idle time),
* we increment the confidence counter for the given target ratio.
* CONFIDENCE_OK defines the level where runtime calibration results are
* valid.
*/
#define CONFIDENCE_OK (3)
/* Default idle injection duration, driver adjust sleep time to meet target
* idle ratio. Similar to frequency modulation.
*/
#define DEFAULT_DURATION_JIFFIES (6)
static struct dentry *debug_dir;
static bool poll_pkg_cstate_enable;
/* Idle ratio observed using package C-state counters */
static unsigned int current_ratio;
/* Skip the idle injection till set to true */
static bool should_skip;
struct powerclamp_data {
unsigned int cpu;
unsigned int count;
unsigned int guard;
unsigned int window_size_now;
unsigned int target_ratio;
bool clamping;
};
static struct powerclamp_data powerclamp_data;
static struct thermal_cooling_device *cooling_dev;
static DEFINE_MUTEX(powerclamp_lock);
/* This duration is in microseconds */
static unsigned int duration;
static unsigned int pkg_cstate_ratio_cur;
static unsigned int window_size;
static int duration_set(const char *arg, const struct kernel_param *kp)
{
int ret = 0;
unsigned long new_duration;
ret = kstrtoul(arg, 10, &new_duration);
if (ret)
goto exit;
if (new_duration > 25 || new_duration < 6) {
pr_err("Out of recommended range %lu, between 6-25ms\n",
new_duration);
ret = -EINVAL;
goto exit;
}
mutex_lock(&powerclamp_lock);
duration = clamp(new_duration, 6ul, 25ul) * 1000;
mutex_unlock(&powerclamp_lock);
exit:
return ret;
}
static int duration_get(char *buf, const struct kernel_param *kp)
{
int ret;
mutex_lock(&powerclamp_lock);
ret = sysfs_emit(buf, "%d\n", duration / 1000);
mutex_unlock(&powerclamp_lock);
return ret;
}
static const struct kernel_param_ops duration_ops = {
.set = duration_set,
.get = duration_get,
};
module_param_cb(duration, &duration_ops, NULL, 0644);
MODULE_PARM_DESC(duration, "forced idle time for each attempt in msec.");
#define DEFAULT_MAX_IDLE 50
#define MAX_ALL_CPU_IDLE 75
static u8 max_idle = DEFAULT_MAX_IDLE;
static cpumask_var_t idle_injection_cpu_mask;
static int allocate_copy_idle_injection_mask(const struct cpumask *copy_mask)
{
if (cpumask_available(idle_injection_cpu_mask))
goto copy_mask;
/* This mask is allocated only one time and freed during module exit */
if (!alloc_cpumask_var(&idle_injection_cpu_mask, GFP_KERNEL))
return -ENOMEM;
copy_mask:
cpumask_copy(idle_injection_cpu_mask, copy_mask);
return 0;
}
/* Return true if the cpumask and idle percent combination is invalid */
static bool check_invalid(cpumask_var_t mask, u8 idle)
{
if (cpumask_equal(cpu_present_mask, mask) && idle > MAX_ALL_CPU_IDLE)
return true;
return false;
}
static int cpumask_set(const char *arg, const struct kernel_param *kp)
{
cpumask_var_t new_mask;
int ret;
mutex_lock(&powerclamp_lock);
/* Can't set mask when cooling device is in use */
if (powerclamp_data.clamping) {
ret = -EAGAIN;
goto skip_cpumask_set;
}
ret = alloc_cpumask_var(&new_mask, GFP_KERNEL);
if (!ret)
goto skip_cpumask_set;
ret = bitmap_parse(arg, strlen(arg), cpumask_bits(new_mask),
nr_cpumask_bits);
if (ret)
goto free_cpumask_set;
if (cpumask_empty(new_mask) || check_invalid(new_mask, max_idle)) {
ret = -EINVAL;
goto free_cpumask_set;
}
/*
* When module parameters are passed from kernel command line
* during insmod, the module parameter callback is called
* before powerclamp_init(), so we can't assume that some
* cpumask can be allocated and copied before here. Also
* in this case this cpumask is used as the default mask.
*/
ret = allocate_copy_idle_injection_mask(new_mask);
free_cpumask_set:
free_cpumask_var(new_mask);
skip_cpumask_set:
mutex_unlock(&powerclamp_lock);
return ret;
}
static int cpumask_get(char *buf, const struct kernel_param *kp)
{
if (!cpumask_available(idle_injection_cpu_mask))
return -ENODEV;
return bitmap_print_to_pagebuf(false, buf, cpumask_bits(idle_injection_cpu_mask),
nr_cpumask_bits);
}
static const struct kernel_param_ops cpumask_ops = {
.set = cpumask_set,
.get = cpumask_get,
};
module_param_cb(cpumask, &cpumask_ops, NULL, 0644);
MODULE_PARM_DESC(cpumask, "Mask of CPUs to use for idle injection.");
static int max_idle_set(const char *arg, const struct kernel_param *kp)
{
u8 new_max_idle;
int ret = 0;
mutex_lock(&powerclamp_lock);
/* Can't set mask when cooling device is in use */
if (powerclamp_data.clamping) {
ret = -EAGAIN;
goto skip_limit_set;
}
ret = kstrtou8(arg, 10, &new_max_idle);
if (ret)
goto skip_limit_set;
if (new_max_idle > MAX_TARGET_RATIO) {
ret = -EINVAL;
goto skip_limit_set;
}
if (!cpumask_available(idle_injection_cpu_mask)) {
ret = allocate_copy_idle_injection_mask(cpu_present_mask);
if (ret)
goto skip_limit_set;
}
if (check_invalid(idle_injection_cpu_mask, new_max_idle)) {
ret = -EINVAL;
goto skip_limit_set;
}
max_idle = new_max_idle;
skip_limit_set:
mutex_unlock(&powerclamp_lock);
return ret;
}
static const struct kernel_param_ops max_idle_ops = {
.set = max_idle_set,
.get = param_get_byte,
};
module_param_cb(max_idle, &max_idle_ops, &max_idle, 0644);
MODULE_PARM_DESC(max_idle, "maximum injected idle time to the total CPU time ratio in percent range:1-100");
struct powerclamp_calibration_data {
unsigned long confidence; /* used for calibration, basically a counter
* gets incremented each time a clamping
* period is completed without extra wakeups
* once that counter is reached given level,
* compensation is deemed usable.
*/
unsigned long steady_comp; /* steady state compensation used when
* no extra wakeups occurred.
*/
unsigned long dynamic_comp; /* compensate excessive wakeup from idle
* mostly from external interrupts.
*/
};
static struct powerclamp_calibration_data cal_data[MAX_TARGET_RATIO];
static int window_size_set(const char *arg, const struct kernel_param *kp)
{
int ret = 0;
unsigned long new_window_size;
ret = kstrtoul(arg, 10, &new_window_size);
if (ret)
goto exit_win;
if (new_window_size > 10 || new_window_size < 2) {
pr_err("Out of recommended window size %lu, between 2-10\n",
new_window_size);
ret = -EINVAL;
}
window_size = clamp(new_window_size, 2ul, 10ul);
smp_mb();
exit_win:
return ret;
}
static const struct kernel_param_ops window_size_ops = {
.set = window_size_set,
.get = param_get_int,
};
module_param_cb(window_size, &window_size_ops, &window_size, 0644);
MODULE_PARM_DESC(window_size, "sliding window in number of clamping cycles\n"
"\tpowerclamp controls idle ratio within this window. larger\n"
"\twindow size results in slower response time but more smooth\n"
"\tclamping results. default to 2.");
struct pkg_cstate_info {
bool skip;
int msr_index;
int cstate_id;
};
#define PKG_CSTATE_INIT(id) { \
.msr_index = MSR_PKG_C##id##_RESIDENCY, \
.cstate_id = id \
}
static struct pkg_cstate_info pkg_cstates[] = {
PKG_CSTATE_INIT(2),
PKG_CSTATE_INIT(3),
PKG_CSTATE_INIT(6),
PKG_CSTATE_INIT(7),
PKG_CSTATE_INIT(8),
PKG_CSTATE_INIT(9),
PKG_CSTATE_INIT(10),
{NULL},
};
static bool has_pkg_state_counter(void)
{
u64 val;
struct pkg_cstate_info *info = pkg_cstates;
/* check if any one of the counter msrs exists */
while (info->msr_index) {
if (!rdmsrl_safe(info->msr_index, &val))
return true;
info++;
}
return false;
}
static u64 pkg_state_counter(void)
{
u64 val;
u64 count = 0;
struct pkg_cstate_info *info = pkg_cstates;
while (info->msr_index) {
if (!info->skip) {
if (!rdmsrl_safe(info->msr_index, &val))
count += val;
else
info->skip = true;
}
info++;
}
return count;
}
static unsigned int get_compensation(int ratio)
{
unsigned int comp = 0;
if (!poll_pkg_cstate_enable)
return 0;
/* we only use compensation if all adjacent ones are good */
if (ratio == 1 &&
cal_data[ratio].confidence >= CONFIDENCE_OK &&
cal_data[ratio + 1].confidence >= CONFIDENCE_OK &&
cal_data[ratio + 2].confidence >= CONFIDENCE_OK) {
comp = (cal_data[ratio].steady_comp +
cal_data[ratio + 1].steady_comp +
cal_data[ratio + 2].steady_comp) / 3;
} else if (ratio == MAX_TARGET_RATIO - 1 &&
cal_data[ratio].confidence >= CONFIDENCE_OK &&
cal_data[ratio - 1].confidence >= CONFIDENCE_OK &&
cal_data[ratio - 2].confidence >= CONFIDENCE_OK) {
comp = (cal_data[ratio].steady_comp +
cal_data[ratio - 1].steady_comp +
cal_data[ratio - 2].steady_comp) / 3;
} else if (cal_data[ratio].confidence >= CONFIDENCE_OK &&
cal_data[ratio - 1].confidence >= CONFIDENCE_OK &&
cal_data[ratio + 1].confidence >= CONFIDENCE_OK) {
comp = (cal_data[ratio].steady_comp +
cal_data[ratio - 1].steady_comp +
cal_data[ratio + 1].steady_comp) / 3;
}
/* do not exceed limit */
if (comp + ratio >= MAX_TARGET_RATIO)
comp = MAX_TARGET_RATIO - ratio - 1;
return comp;
}
static void adjust_compensation(int target_ratio, unsigned int win)
{
int delta;
struct powerclamp_calibration_data *d = &cal_data[target_ratio];
/*
* adjust compensations if confidence level has not been reached.
*/
if (d->confidence >= CONFIDENCE_OK)
return;
delta = powerclamp_data.target_ratio - current_ratio;
/* filter out bad data */
if (delta >= 0 && delta <= (1+target_ratio/10)) {
if (d->steady_comp)
d->steady_comp =
roundup(delta+d->steady_comp, 2)/2;
else
d->steady_comp = delta;
d->confidence++;
}
}
static bool powerclamp_adjust_controls(unsigned int target_ratio,
unsigned int guard, unsigned int win)
{
static u64 msr_last, tsc_last;
u64 msr_now, tsc_now;
u64 val64;
/* check result for the last window */
msr_now = pkg_state_counter();
tsc_now = rdtsc();
/* calculate pkg cstate vs tsc ratio */
if (!msr_last || !tsc_last)
current_ratio = 1;
else if (tsc_now-tsc_last) {
val64 = 100*(msr_now-msr_last);
do_div(val64, (tsc_now-tsc_last));
current_ratio = val64;
}
/* update record */
msr_last = msr_now;
tsc_last = tsc_now;
adjust_compensation(target_ratio, win);
/* if we are above target+guard, skip */
return powerclamp_data.target_ratio + guard <= current_ratio;
}
/*
* This function calculates runtime from the current target ratio.
* This function gets called under powerclamp_lock.
*/
static unsigned int get_run_time(void)
{
unsigned int compensated_ratio;
unsigned int runtime;
/*
* make sure user selected ratio does not take effect until
* the next round. adjust target_ratio if user has changed
* target such that we can converge quickly.
*/
powerclamp_data.guard = 1 + powerclamp_data.target_ratio / 20;
powerclamp_data.window_size_now = window_size;
/*
* systems may have different ability to enter package level
* c-states, thus we need to compensate the injected idle ratio
* to achieve the actual target reported by the HW.
*/
compensated_ratio = powerclamp_data.target_ratio +
get_compensation(powerclamp_data.target_ratio);
if (compensated_ratio <= 0)
compensated_ratio = 1;
runtime = duration * 100 / compensated_ratio - duration;
return runtime;
}
/*
* 1 HZ polling while clamping is active, useful for userspace
* to monitor actual idle ratio.
*/
static void poll_pkg_cstate(struct work_struct *dummy);
static DECLARE_DELAYED_WORK(poll_pkg_cstate_work, poll_pkg_cstate);
static void poll_pkg_cstate(struct work_struct *dummy)
{
static u64 msr_last;
static u64 tsc_last;
u64 msr_now;
u64 tsc_now;
u64 val64;
msr_now = pkg_state_counter();
tsc_now = rdtsc();
/* calculate pkg cstate vs tsc ratio */
if (!msr_last || !tsc_last)
pkg_cstate_ratio_cur = 1;
else {
if (tsc_now - tsc_last) {
val64 = 100 * (msr_now - msr_last);
do_div(val64, (tsc_now - tsc_last));
pkg_cstate_ratio_cur = val64;
}
}
/* update record */
msr_last = msr_now;
tsc_last = tsc_now;
mutex_lock(&powerclamp_lock);
if (powerclamp_data.clamping)
schedule_delayed_work(&poll_pkg_cstate_work, HZ);
mutex_unlock(&powerclamp_lock);
}
static struct idle_inject_device *ii_dev;
/*
* This function is called from idle injection core on timer expiry
* for the run duration. This allows powerclamp to readjust or skip
* injecting idle for this cycle.
*/
static bool idle_inject_update(void)
{
bool update = false;
/* We can't sleep in this callback */
if (!mutex_trylock(&powerclamp_lock))
return true;
if (!(powerclamp_data.count % powerclamp_data.window_size_now)) {
should_skip = powerclamp_adjust_controls(powerclamp_data.target_ratio,
powerclamp_data.guard,
powerclamp_data.window_size_now);
update = true;
}
if (update) {
unsigned int runtime = get_run_time();
idle_inject_set_duration(ii_dev, runtime, duration);
}
powerclamp_data.count++;
mutex_unlock(&powerclamp_lock);
if (should_skip)
return false;
return true;
}
/* This function starts idle injection by calling idle_inject_start() */
static void trigger_idle_injection(void)
{
unsigned int runtime = get_run_time();
idle_inject_set_duration(ii_dev, runtime, duration);
idle_inject_start(ii_dev);
powerclamp_data.clamping = true;
}
/*
* This function is called from start_power_clamp() to register
* CPUS with powercap idle injection register and set default
* idle duration and latency.
*/
static int powerclamp_idle_injection_register(void)
{
poll_pkg_cstate_enable = false;
if (cpumask_equal(cpu_present_mask, idle_injection_cpu_mask)) {
ii_dev = idle_inject_register_full(idle_injection_cpu_mask, idle_inject_update);
if (topology_max_packages() == 1 && topology_max_dies_per_package() == 1)
poll_pkg_cstate_enable = true;
} else {
ii_dev = idle_inject_register(idle_injection_cpu_mask);
}
if (!ii_dev) {
pr_err("powerclamp: idle_inject_register failed\n");
return -EAGAIN;
}
idle_inject_set_duration(ii_dev, TICK_USEC, duration);
idle_inject_set_latency(ii_dev, UINT_MAX);
return 0;
}
/*
* This function is called from end_power_clamp() to stop idle injection
* and unregister CPUS from powercap idle injection core.
*/
static void remove_idle_injection(void)
{
if (!powerclamp_data.clamping)
return;
powerclamp_data.clamping = false;
idle_inject_stop(ii_dev);
}
/*
* This function is called when user change the cooling device
* state from zero to some other value.
*/
static int start_power_clamp(void)
{
int ret;
ret = powerclamp_idle_injection_register();
if (!ret) {
trigger_idle_injection();
if (poll_pkg_cstate_enable)
schedule_delayed_work(&poll_pkg_cstate_work, 0);
}
return ret;
}
/*
* This function is called when user change the cooling device
* state from non zero value zero.
*/
static void end_power_clamp(void)
{
if (powerclamp_data.clamping) {
remove_idle_injection();
idle_inject_unregister(ii_dev);
}
}
static int powerclamp_get_max_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
*state = MAX_TARGET_RATIO;
return 0;
}
static int powerclamp_get_cur_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
mutex_lock(&powerclamp_lock);
*state = powerclamp_data.target_ratio;
mutex_unlock(&powerclamp_lock);
return 0;
}
static int powerclamp_set_cur_state(struct thermal_cooling_device *cdev,
unsigned long new_target_ratio)
{
int ret = 0;
mutex_lock(&powerclamp_lock);
new_target_ratio = clamp(new_target_ratio, 0UL,
(unsigned long) (max_idle - 1));
if (powerclamp_data.target_ratio == new_target_ratio)
goto exit_set;
if (!powerclamp_data.target_ratio && new_target_ratio > 0) {
pr_info("Start idle injection to reduce power\n");
powerclamp_data.target_ratio = new_target_ratio;
ret = start_power_clamp();
if (ret)
powerclamp_data.target_ratio = 0;
goto exit_set;
} else if (powerclamp_data.target_ratio > 0 && new_target_ratio == 0) {
pr_info("Stop forced idle injection\n");
end_power_clamp();
powerclamp_data.target_ratio = 0;
} else /* adjust currently running */ {
unsigned int runtime;
powerclamp_data.target_ratio = new_target_ratio;
runtime = get_run_time();
idle_inject_set_duration(ii_dev, runtime, duration);
}
exit_set:
mutex_unlock(&powerclamp_lock);
return ret;
}
/* bind to generic thermal layer as cooling device*/
static const struct thermal_cooling_device_ops powerclamp_cooling_ops = {
.get_max_state = powerclamp_get_max_state,
.get_cur_state = powerclamp_get_cur_state,
.set_cur_state = powerclamp_set_cur_state,
};
static const struct x86_cpu_id __initconst intel_powerclamp_ids[] = {
X86_MATCH_VENDOR_FEATURE(INTEL, X86_FEATURE_MWAIT, NULL),
{}
};
MODULE_DEVICE_TABLE(x86cpu, intel_powerclamp_ids);
static int __init powerclamp_probe(void)
{
if (!x86_match_cpu(intel_powerclamp_ids)) {
pr_err("CPU does not support MWAIT\n");
return -ENODEV;
}
/* The goal for idle time alignment is to achieve package cstate. */
if (!has_pkg_state_counter()) {
pr_info("No package C-state available\n");
return -ENODEV;
}
return 0;
}
static int powerclamp_debug_show(struct seq_file *m, void *unused)
{
int i = 0;
seq_printf(m, "pct confidence steady dynamic (compensation)\n");
for (i = 0; i < MAX_TARGET_RATIO; i++) {
seq_printf(m, "%d\t%lu\t%lu\t%lu\n",
i,
cal_data[i].confidence,
cal_data[i].steady_comp,
cal_data[i].dynamic_comp);
}
return 0;
}
DEFINE_SHOW_ATTRIBUTE(powerclamp_debug);
static inline void powerclamp_create_debug_files(void)
{
debug_dir = debugfs_create_dir("intel_powerclamp", NULL);
debugfs_create_file("powerclamp_calib", S_IRUGO, debug_dir, cal_data,
&powerclamp_debug_fops);
}
static int __init powerclamp_init(void)
{
int retval;
/* probe cpu features and ids here */
retval = powerclamp_probe();
if (retval)
return retval;
mutex_lock(&powerclamp_lock);
if (!cpumask_available(idle_injection_cpu_mask))
retval = allocate_copy_idle_injection_mask(cpu_present_mask);
mutex_unlock(&powerclamp_lock);
if (retval)
return retval;
/* set default limit, maybe adjusted during runtime based on feedback */
window_size = 2;
cooling_dev = thermal_cooling_device_register("intel_powerclamp", NULL,
&powerclamp_cooling_ops);
if (IS_ERR(cooling_dev))
return -ENODEV;
if (!duration)
duration = jiffies_to_usecs(DEFAULT_DURATION_JIFFIES);
powerclamp_create_debug_files();
return 0;
}
module_init(powerclamp_init);
static void __exit powerclamp_exit(void)
{
mutex_lock(&powerclamp_lock);
end_power_clamp();
mutex_unlock(&powerclamp_lock);
thermal_cooling_device_unregister(cooling_dev);
cancel_delayed_work_sync(&poll_pkg_cstate_work);
debugfs_remove_recursive(debug_dir);
if (cpumask_available(idle_injection_cpu_mask))
free_cpumask_var(idle_injection_cpu_mask);
}
module_exit(powerclamp_exit);
MODULE_IMPORT_NS(IDLE_INJECT);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arjan van de Ven <[email protected]>");
MODULE_AUTHOR("Jacob Pan <[email protected]>");
MODULE_DESCRIPTION("Package Level C-state Idle Injection for Intel CPUs");
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