drivers/cpufreq/cpufreq_stats.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  *  drivers/cpufreq/cpufreq_stats.c
  *
  *  Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
  *  (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.
  */

 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/module.h>
 #include <linux/sched/clock.h>
 #include <linux/slab.h>

 struct cpufreq_stats {
 	unsigned int total_trans;
 	unsigned long long last_time;
 	unsigned int max_state;
 	unsigned int state_num;
 	unsigned int last_index;
 	u64 *time_in_state;
 	unsigned int *freq_table;
 	unsigned int *trans_table;

 	/* Deferred reset */
 	unsigned int reset_pending;
 	unsigned long long reset_time;
 };

 static void cpufreq_stats_update(struct cpufreq_stats *stats,
 				 unsigned long long time)
 {
 	unsigned long long cur_time = local_clock();

 	stats->time_in_state[stats->last_index] += cur_time - time;
 	stats->last_time = cur_time;
 }

 static void cpufreq_stats_reset_table(struct cpufreq_stats *stats)
 {
 	unsigned int count = stats->max_state;

 	memset(stats->time_in_state, 0, count * sizeof(u64));
 	memset(stats->trans_table, 0, count * count * sizeof(int));
 	stats->last_time = local_clock();
 	stats->total_trans = 0;

 	/* Adjust for the time elapsed since reset was requested */
 	WRITE_ONCE(stats->reset_pending, 0);
 	/*
 	 * Prevent the reset_time read from being reordered before the
 	 * reset_pending accesses in cpufreq_stats_record_transition().
 	 */
 	smp_rmb();
 	cpufreq_stats_update(stats, READ_ONCE(stats->reset_time));
 }

 static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
 {
 	struct cpufreq_stats *stats = policy->stats;

 	if (READ_ONCE(stats->reset_pending))
 		return sprintf(buf, "%d\n", 0);
 	else
 		return sprintf(buf, "%u\n", stats->total_trans);
 }
 cpufreq_freq_attr_ro(total_trans);

 static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
 {
 	struct cpufreq_stats *stats = policy->stats;
 	bool pending = READ_ONCE(stats->reset_pending);
 	unsigned long long time;
 	ssize_t len = 0;
 	int i;

 	for (i = 0; i < stats->state_num; i++) {
 		if (pending) {
 			if (i == stats->last_index) {
 				/*
 				 * Prevent the reset_time read from occurring
 				 * before the reset_pending read above.
 				 */
 				smp_rmb();
 				time = local_clock() - READ_ONCE(stats->reset_time);
 			} else {
 				time = 0;
 			}
 		} else {
 			time = stats->time_in_state[i];
 			if (i == stats->last_index)
 				time += local_clock() - stats->last_time;
 		}

 		len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
 			       nsec_to_clock_t(time));
 	}
 	return len;
 }
 cpufreq_freq_attr_ro(time_in_state);

 /* We don't care what is written to the attribute */
 static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,
 			   size_t count)
 {
 	struct cpufreq_stats *stats = policy->stats;

 	/*
 	 * Defer resetting of stats to cpufreq_stats_record_transition() to
 	 * avoid races.
 	 */
 	WRITE_ONCE(stats->reset_time, local_clock());
 	/*
 	 * The memory barrier below is to prevent the readers of reset_time from
 	 * seeing a stale or partially updated value.
 	 */
 	smp_wmb();
 	WRITE_ONCE(stats->reset_pending, 1);

 	return count;
 }
 cpufreq_freq_attr_wo(reset);

 static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
 {
 	struct cpufreq_stats *stats = policy->stats;
 	bool pending = READ_ONCE(stats->reset_pending);
 	ssize_t len = 0;
 	int i, j, count;

 	len += sysfs_emit_at(buf, len, "   From  :    To\n");
 	len += sysfs_emit_at(buf, len, "         : ");
 	for (i = 0; i < stats->state_num; i++) {
 		if (len >= PAGE_SIZE)
 			break;
 		len += sysfs_emit_at(buf, len, "%9u ", stats->freq_table[i]);
 	}
 	if (len >= PAGE_SIZE)
 		return PAGE_SIZE;

 	len += sysfs_emit_at(buf, len, "\n");

 	for (i = 0; i < stats->state_num; i++) {
 		if (len >= PAGE_SIZE)
 			break;

 		len += sysfs_emit_at(buf, len, "%9u: ", stats->freq_table[i]);

 		for (j = 0; j < stats->state_num; j++) {
 			if (len >= PAGE_SIZE)
 				break;

 			if (pending)
 				count = 0;
 			else
 				count = stats->trans_table[i * stats->max_state + j];

 			len += sysfs_emit_at(buf, len, "%9u ", count);
 		}
 		if (len >= PAGE_SIZE)
 			break;
 		len += sysfs_emit_at(buf, len, "\n");
 	}

 	if (len >= PAGE_SIZE) {
 		pr_warn_once("cpufreq transition table exceeds PAGE_SIZE. Disabling\n");
 		return -EFBIG;
 	}
 	return len;
 }
 cpufreq_freq_attr_ro(trans_table);

 static struct attribute *default_attrs[] = {
 	&total_trans.attr,
 	&time_in_state.attr,
 	&reset.attr,
 	&trans_table.attr,
 	NULL
 };
 static const struct attribute_group stats_attr_group = {
 	.attrs = default_attrs,
 	.name = "stats"
 };

 static int freq_table_get_index(struct cpufreq_stats *stats, unsigned int freq)
 {
 	int index;
 	for (index = 0; index < stats->max_state; index++)
 		if (stats->freq_table[index] == freq)
 			return index;
 	return -1;
 }

 void cpufreq_stats_free_table(struct cpufreq_policy *policy)
 {
 	struct cpufreq_stats *stats = policy->stats;

 	/* Already freed */
 	if (!stats)
 		return;

 	pr_debug("%s: Free stats table\n", __func__);

 	sysfs_remove_group(&policy->kobj, &stats_attr_group);
 	kfree(stats->time_in_state);
 	kfree(stats);
 	policy->stats = NULL;
 }

 void cpufreq_stats_create_table(struct cpufreq_policy *policy)
 {
 	unsigned int i = 0, count;
 	struct cpufreq_stats *stats;
 	unsigned int alloc_size;
 	struct cpufreq_frequency_table *pos;

 	count = cpufreq_table_count_valid_entries(policy);
 	if (!count)
 		return;

 	/* stats already initialized */
 	if (policy->stats)
 		return;

 	stats = kzalloc(sizeof(*stats), GFP_KERNEL);
 	if (!stats)
 		return;

 	alloc_size = count * sizeof(int) + count * sizeof(u64);

 	alloc_size += count * count * sizeof(int);

 	/* Allocate memory for time_in_state/freq_table/trans_table in one go */
 	stats->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
 	if (!stats->time_in_state)
 		goto free_stat;

 	stats->freq_table = (unsigned int *)(stats->time_in_state + count);

 	stats->trans_table = stats->freq_table + count;

 	stats->max_state = count;

 	/* Find valid-unique entries */
 	cpufreq_for_each_valid_entry(pos, policy->freq_table)
 		if (freq_table_get_index(stats, pos->frequency) == -1)
 			stats->freq_table[i++] = pos->frequency;

 	stats->state_num = i;
 	stats->last_time = local_clock();
 	stats->last_index = freq_table_get_index(stats, policy->cur);

 	policy->stats = stats;
 	if (!sysfs_create_group(&policy->kobj, &stats_attr_group))
 		return;

 	/* We failed, release resources */
 	policy->stats = NULL;
 	kfree(stats->time_in_state);
 free_stat:
 	kfree(stats);
 }

 void cpufreq_stats_record_transition(struct cpufreq_policy *policy,
 				     unsigned int new_freq)
 {
 	struct cpufreq_stats *stats = policy->stats;
 	int old_index, new_index;

 	if (unlikely(!stats))
 		return;

 	if (unlikely(READ_ONCE(stats->reset_pending)))
 		cpufreq_stats_reset_table(stats);

 	old_index = stats->last_index;
 	new_index = freq_table_get_index(stats, new_freq);

 	/* We can't do stats->time_in_state[-1]= .. */
 	if (unlikely(old_index == -1 || new_index == -1 || old_index == new_index))
 		return;

 	cpufreq_stats_update(stats, stats->last_time);

 	stats->last_index = new_index;
 	stats->trans_table[old_index * stats->max_state + new_index]++;
 	stats->total_trans++;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* drivers/cpufreq/cpufreq_stats.c
	*
	* Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
	* (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.
	*/

	#include <linux/cpu.h>
	#include <linux/cpufreq.h>
	#include <linux/module.h>
	#include <linux/sched/clock.h>
	#include <linux/slab.h>

	struct cpufreq_stats {
	unsigned int total_trans;
	unsigned long long last_time;
	unsigned int max_state;
	unsigned int state_num;
	unsigned int last_index;
	u64 *time_in_state;
	unsigned int *freq_table;
	unsigned int *trans_table;

	/* Deferred reset */
	unsigned int reset_pending;
	unsigned long long reset_time;
	};

	static void cpufreq_stats_update(struct cpufreq_stats *stats,
	unsigned long long time)
	{
	unsigned long long cur_time = local_clock();

	stats->time_in_state[stats->last_index] += cur_time - time;
	stats->last_time = cur_time;
	}

	static void cpufreq_stats_reset_table(struct cpufreq_stats *stats)
	{
	unsigned int count = stats->max_state;

	memset(stats->time_in_state, 0, count * sizeof(u64));
	memset(stats->trans_table, 0, count * count * sizeof(int));
	stats->last_time = local_clock();
	stats->total_trans = 0;

	/* Adjust for the time elapsed since reset was requested */
	WRITE_ONCE(stats->reset_pending, 0);
	/*
	* Prevent the reset_time read from being reordered before the
	* reset_pending accesses in cpufreq_stats_record_transition().
	*/
	smp_rmb();
	cpufreq_stats_update(stats, READ_ONCE(stats->reset_time));
	}

	static ssize_t show_total_trans(struct cpufreq_policy policy, char buf)
	{
	struct cpufreq_stats *stats = policy->stats;

	if (READ_ONCE(stats->reset_pending))
	return sprintf(buf, "%d\n", 0);
	else
	return sprintf(buf, "%u\n", stats->total_trans);
	}
	cpufreq_freq_attr_ro(total_trans);

	static ssize_t show_time_in_state(struct cpufreq_policy policy, char buf)
	{
	struct cpufreq_stats *stats = policy->stats;
	bool pending = READ_ONCE(stats->reset_pending);
	unsigned long long time;
	ssize_t len = 0;
	int i;

	for (i = 0; i < stats->state_num; i++) {
	if (pending) {
	if (i == stats->last_index) {
	/*
	* Prevent the reset_time read from occurring
	* before the reset_pending read above.
	*/
	smp_rmb();
	time = local_clock() - READ_ONCE(stats->reset_time);
	} else {
	time = 0;
	}
	} else {
	time = stats->time_in_state[i];
	if (i == stats->last_index)
	time += local_clock() - stats->last_time;
	}

	len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
	nsec_to_clock_t(time));
	}
	return len;
	}
	cpufreq_freq_attr_ro(time_in_state);

	/* We don't care what is written to the attribute */
	static ssize_t store_reset(struct cpufreq_policy policy, const char buf,
	size_t count)
	{
	struct cpufreq_stats *stats = policy->stats;

	/*
	* Defer resetting of stats to cpufreq_stats_record_transition() to
	* avoid races.
	*/
	WRITE_ONCE(stats->reset_time, local_clock());
	/*
	* The memory barrier below is to prevent the readers of reset_time from
	* seeing a stale or partially updated value.
	*/
	smp_wmb();
	WRITE_ONCE(stats->reset_pending, 1);

	return count;
	}
	cpufreq_freq_attr_wo(reset);

	static ssize_t show_trans_table(struct cpufreq_policy policy, char buf)
	{
	struct cpufreq_stats *stats = policy->stats;
	bool pending = READ_ONCE(stats->reset_pending);
	ssize_t len = 0;
	int i, j, count;

	len += sysfs_emit_at(buf, len, " From : To\n");
	len += sysfs_emit_at(buf, len, " : ");
	for (i = 0; i < stats->state_num; i++) {
	if (len >= PAGE_SIZE)
	break;
	len += sysfs_emit_at(buf, len, "%9u ", stats->freq_table[i]);
	}
	if (len >= PAGE_SIZE)
	return PAGE_SIZE;

	len += sysfs_emit_at(buf, len, "\n");

	for (i = 0; i < stats->state_num; i++) {
	if (len >= PAGE_SIZE)
	break;

	len += sysfs_emit_at(buf, len, "%9u: ", stats->freq_table[i]);

	for (j = 0; j < stats->state_num; j++) {
	if (len >= PAGE_SIZE)
	break;

	if (pending)
	count = 0;
	else
	count = stats->trans_table[i * stats->max_state + j];

	len += sysfs_emit_at(buf, len, "%9u ", count);
	}
	if (len >= PAGE_SIZE)
	break;
	len += sysfs_emit_at(buf, len, "\n");
	}

	if (len >= PAGE_SIZE) {
	pr_warn_once("cpufreq transition table exceeds PAGE_SIZE. Disabling\n");
	return -EFBIG;
	}
	return len;
	}
	cpufreq_freq_attr_ro(trans_table);

	static struct attribute *default_attrs[] = {
	&total_trans.attr,
	&time_in_state.attr,
	&reset.attr,
	&trans_table.attr,
	NULL
	};
	static const struct attribute_group stats_attr_group = {
	.attrs = default_attrs,
	.name = "stats"
	};

	static int freq_table_get_index(struct cpufreq_stats *stats, unsigned int freq)
	{
	int index;
	for (index = 0; index < stats->max_state; index++)
	if (stats->freq_table[index] == freq)
	return index;
	return -1;
	}

	void cpufreq_stats_free_table(struct cpufreq_policy *policy)
	{
	struct cpufreq_stats *stats = policy->stats;

	/* Already freed */
	if (!stats)
	return;

	pr_debug("%s: Free stats table\n", __func__);

	sysfs_remove_group(&policy->kobj, &stats_attr_group);
	kfree(stats->time_in_state);
	kfree(stats);
	policy->stats = NULL;
	}

	void cpufreq_stats_create_table(struct cpufreq_policy *policy)
	{
	unsigned int i = 0, count;
	struct cpufreq_stats *stats;
	unsigned int alloc_size;
	struct cpufreq_frequency_table *pos;

	count = cpufreq_table_count_valid_entries(policy);
	if (!count)
	return;

	/* stats already initialized */
	if (policy->stats)
	return;

	stats = kzalloc(sizeof(*stats), GFP_KERNEL);
	if (!stats)
	return;

	alloc_size = count * sizeof(int) + count * sizeof(u64);

	alloc_size += count * count * sizeof(int);

	/* Allocate memory for time_in_state/freq_table/trans_table in one go */
	stats->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
	if (!stats->time_in_state)
	goto free_stat;

	stats->freq_table = (unsigned int *)(stats->time_in_state + count);

	stats->trans_table = stats->freq_table + count;

	stats->max_state = count;

	/* Find valid-unique entries */
	cpufreq_for_each_valid_entry(pos, policy->freq_table)
	if (freq_table_get_index(stats, pos->frequency) == -1)
	stats->freq_table[i++] = pos->frequency;

	stats->state_num = i;
	stats->last_time = local_clock();
	stats->last_index = freq_table_get_index(stats, policy->cur);

	policy->stats = stats;
	if (!sysfs_create_group(&policy->kobj, &stats_attr_group))
	return;

	/* We failed, release resources */
	policy->stats = NULL;
	kfree(stats->time_in_state);
	free_stat:
	kfree(stats);
	}

	void cpufreq_stats_record_transition(struct cpufreq_policy *policy,
	unsigned int new_freq)
	{
	struct cpufreq_stats *stats = policy->stats;
	int old_index, new_index;

	if (unlikely(!stats))
	return;

	if (unlikely(READ_ONCE(stats->reset_pending)))
	cpufreq_stats_reset_table(stats);

	old_index = stats->last_index;
	new_index = freq_table_get_index(stats, new_freq);

	/* We can't do stats->time_in_state[-1]= .. */
	if (unlikely(old_index == -1 \|\| new_index == -1 \|\| old_index == new_index))
	return;

	cpufreq_stats_update(stats, stats->last_time);

	stats->last_index = new_index;
	stats->trans_table[old_index * stats->max_state + new_index]++;
	stats->total_trans++;
	}