290 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * drivers/cpufreq/cpufreq_stats.c4 *5 * Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.6 * (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.7 */8 9#include <linux/cpu.h>10#include <linux/cpufreq.h>11#include <linux/module.h>12#include <linux/sched/clock.h>13#include <linux/slab.h>14 15struct cpufreq_stats {16 unsigned int total_trans;17 unsigned long long last_time;18 unsigned int max_state;19 unsigned int state_num;20 unsigned int last_index;21 u64 *time_in_state;22 unsigned int *freq_table;23 unsigned int *trans_table;24 25 /* Deferred reset */26 unsigned int reset_pending;27 unsigned long long reset_time;28};29 30static void cpufreq_stats_update(struct cpufreq_stats *stats,31 unsigned long long time)32{33 unsigned long long cur_time = local_clock();34 35 stats->time_in_state[stats->last_index] += cur_time - time;36 stats->last_time = cur_time;37}38 39static void cpufreq_stats_reset_table(struct cpufreq_stats *stats)40{41 unsigned int count = stats->max_state;42 43 memset(stats->time_in_state, 0, count * sizeof(u64));44 memset(stats->trans_table, 0, count * count * sizeof(int));45 stats->last_time = local_clock();46 stats->total_trans = 0;47 48 /* Adjust for the time elapsed since reset was requested */49 WRITE_ONCE(stats->reset_pending, 0);50 /*51 * Prevent the reset_time read from being reordered before the52 * reset_pending accesses in cpufreq_stats_record_transition().53 */54 smp_rmb();55 cpufreq_stats_update(stats, READ_ONCE(stats->reset_time));56}57 58static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)59{60 struct cpufreq_stats *stats = policy->stats;61 62 if (READ_ONCE(stats->reset_pending))63 return sprintf(buf, "%d\n", 0);64 else65 return sprintf(buf, "%u\n", stats->total_trans);66}67cpufreq_freq_attr_ro(total_trans);68 69static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)70{71 struct cpufreq_stats *stats = policy->stats;72 bool pending = READ_ONCE(stats->reset_pending);73 unsigned long long time;74 ssize_t len = 0;75 int i;76 77 for (i = 0; i < stats->state_num; i++) {78 if (pending) {79 if (i == stats->last_index) {80 /*81 * Prevent the reset_time read from occurring82 * before the reset_pending read above.83 */84 smp_rmb();85 time = local_clock() - READ_ONCE(stats->reset_time);86 } else {87 time = 0;88 }89 } else {90 time = stats->time_in_state[i];91 if (i == stats->last_index)92 time += local_clock() - stats->last_time;93 }94 95 len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],96 nsec_to_clock_t(time));97 }98 return len;99}100cpufreq_freq_attr_ro(time_in_state);101 102/* We don't care what is written to the attribute */103static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,104 size_t count)105{106 struct cpufreq_stats *stats = policy->stats;107 108 /*109 * Defer resetting of stats to cpufreq_stats_record_transition() to110 * avoid races.111 */112 WRITE_ONCE(stats->reset_time, local_clock());113 /*114 * The memory barrier below is to prevent the readers of reset_time from115 * seeing a stale or partially updated value.116 */117 smp_wmb();118 WRITE_ONCE(stats->reset_pending, 1);119 120 return count;121}122cpufreq_freq_attr_wo(reset);123 124static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)125{126 struct cpufreq_stats *stats = policy->stats;127 bool pending = READ_ONCE(stats->reset_pending);128 ssize_t len = 0;129 int i, j, count;130 131 len += sysfs_emit_at(buf, len, " From : To\n");132 len += sysfs_emit_at(buf, len, " : ");133 for (i = 0; i < stats->state_num; i++) {134 if (len >= PAGE_SIZE - 1)135 break;136 len += sysfs_emit_at(buf, len, "%9u ", stats->freq_table[i]);137 }138 if (len >= PAGE_SIZE - 1)139 return PAGE_SIZE - 1;140 141 len += sysfs_emit_at(buf, len, "\n");142 143 for (i = 0; i < stats->state_num; i++) {144 if (len >= PAGE_SIZE - 1)145 break;146 147 len += sysfs_emit_at(buf, len, "%9u: ", stats->freq_table[i]);148 149 for (j = 0; j < stats->state_num; j++) {150 if (len >= PAGE_SIZE - 1)151 break;152 153 if (pending)154 count = 0;155 else156 count = stats->trans_table[i * stats->max_state + j];157 158 len += sysfs_emit_at(buf, len, "%9u ", count);159 }160 if (len >= PAGE_SIZE - 1)161 break;162 len += sysfs_emit_at(buf, len, "\n");163 }164 165 if (len >= PAGE_SIZE - 1) {166 pr_warn_once("cpufreq transition table exceeds PAGE_SIZE. Disabling\n");167 return -EFBIG;168 }169 return len;170}171cpufreq_freq_attr_ro(trans_table);172 173static struct attribute *default_attrs[] = {174 &total_trans.attr,175 &time_in_state.attr,176 &reset.attr,177 &trans_table.attr,178 NULL179};180static const struct attribute_group stats_attr_group = {181 .attrs = default_attrs,182 .name = "stats"183};184 185static int freq_table_get_index(struct cpufreq_stats *stats, unsigned int freq)186{187 int index;188 for (index = 0; index < stats->max_state; index++)189 if (stats->freq_table[index] == freq)190 return index;191 return -1;192}193 194void cpufreq_stats_free_table(struct cpufreq_policy *policy)195{196 struct cpufreq_stats *stats = policy->stats;197 198 /* Already freed */199 if (!stats)200 return;201 202 pr_debug("%s: Free stats table\n", __func__);203 204 sysfs_remove_group(&policy->kobj, &stats_attr_group);205 kfree(stats->time_in_state);206 kfree(stats);207 policy->stats = NULL;208}209 210void cpufreq_stats_create_table(struct cpufreq_policy *policy)211{212 unsigned int i = 0, count;213 struct cpufreq_stats *stats;214 unsigned int alloc_size;215 struct cpufreq_frequency_table *pos;216 217 count = cpufreq_table_count_valid_entries(policy);218 if (!count)219 return;220 221 /* stats already initialized */222 if (policy->stats)223 return;224 225 stats = kzalloc(sizeof(*stats), GFP_KERNEL);226 if (!stats)227 return;228 229 alloc_size = count * sizeof(int) + count * sizeof(u64);230 231 alloc_size += count * count * sizeof(int);232 233 /* Allocate memory for time_in_state/freq_table/trans_table in one go */234 stats->time_in_state = kzalloc(alloc_size, GFP_KERNEL);235 if (!stats->time_in_state)236 goto free_stat;237 238 stats->freq_table = (unsigned int *)(stats->time_in_state + count);239 240 stats->trans_table = stats->freq_table + count;241 242 stats->max_state = count;243 244 /* Find valid-unique entries */245 cpufreq_for_each_valid_entry(pos, policy->freq_table)246 if (policy->freq_table_sorted != CPUFREQ_TABLE_UNSORTED ||247 freq_table_get_index(stats, pos->frequency) == -1)248 stats->freq_table[i++] = pos->frequency;249 250 stats->state_num = i;251 stats->last_time = local_clock();252 stats->last_index = freq_table_get_index(stats, policy->cur);253 254 policy->stats = stats;255 if (!sysfs_create_group(&policy->kobj, &stats_attr_group))256 return;257 258 /* We failed, release resources */259 policy->stats = NULL;260 kfree(stats->time_in_state);261free_stat:262 kfree(stats);263}264 265void cpufreq_stats_record_transition(struct cpufreq_policy *policy,266 unsigned int new_freq)267{268 struct cpufreq_stats *stats = policy->stats;269 int old_index, new_index;270 271 if (unlikely(!stats))272 return;273 274 if (unlikely(READ_ONCE(stats->reset_pending)))275 cpufreq_stats_reset_table(stats);276 277 old_index = stats->last_index;278 new_index = freq_table_get_index(stats, new_freq);279 280 /* We can't do stats->time_in_state[-1]= .. */281 if (unlikely(old_index == -1 || new_index == -1 || old_index == new_index))282 return;283 284 cpufreq_stats_update(stats, stats->last_time);285 286 stats->last_index = new_index;287 stats->trans_table[old_index * stats->max_state + new_index]++;288 stats->total_trans++;289}290