projects/linux·blob master · refs

289 lines · 7.1 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/cpufreq/cpufreq_stats.c
4 *
5 * Copyright (C) 2003-2004 Venkatesh Pallipadi <[email protected]>.
6 * (C) 2004 Zou Nan hai <[email protected]>.
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 the
52 * 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 else
65 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 occurring
82 * 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() to
110 * 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 from
115 * 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 else
156 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 NULL
179};
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_obj(*stats);
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}