1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * CPU accounting code for task groups.
5 *
6 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
7 * (balbir@in.ibm.com).
8 */
9
10 /* Time spent by the tasks of the CPU accounting group executing in ... */
11 enum cpuacct_stat_index {
12 CPUACCT_STAT_USER, /* ... user mode */
13 CPUACCT_STAT_SYSTEM, /* ... kernel mode */
14
15 CPUACCT_STAT_NSTATS,
16 };
17
18 static const char * const cpuacct_stat_desc[] = {
19 [CPUACCT_STAT_USER] = "user",
20 [CPUACCT_STAT_SYSTEM] = "system",
21 };
22
23 /* track CPU usage of a group of tasks and its child groups */
24 struct cpuacct {
25 struct cgroup_subsys_state css;
26 /* cpuusage holds pointer to a u64-type object on every CPU */
27 u64 __percpu *cpuusage;
28 struct kernel_cpustat __percpu *cpustat;
29 };
30
31 static inline struct cpuacct *css_ca(struct cgroup_subsys_state *css)
32 {
33 return css ? container_of(css, struct cpuacct, css) : NULL;
34 }
35
36 /* Return CPU accounting group to which this task belongs */
37 static inline struct cpuacct *task_ca(struct task_struct *tsk)
38 {
39 return css_ca(task_css(tsk, cpuacct_cgrp_id));
40 }
41
42 static inline struct cpuacct *parent_ca(struct cpuacct *ca)
43 {
44 return css_ca(ca->css.parent);
45 }
46
47 static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
48 static struct cpuacct root_cpuacct = {
49 .cpustat = &kernel_cpustat,
50 .cpuusage = &root_cpuacct_cpuusage,
51 };
52
53 /* Create a new CPU accounting group */
54 static struct cgroup_subsys_state *
55 cpuacct_css_alloc(struct cgroup_subsys_state *parent_css)
56 {
57 struct cpuacct *ca;
58
59 if (!parent_css)
60 return &root_cpuacct.css;
61
62 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
63 if (!ca)
64 goto out;
65
66 ca->cpuusage = alloc_percpu(u64);
67 if (!ca->cpuusage)
68 goto out_free_ca;
69
70 ca->cpustat = alloc_percpu(struct kernel_cpustat);
71 if (!ca->cpustat)
72 goto out_free_cpuusage;
73
74 return &ca->css;
75
76 out_free_cpuusage:
77 free_percpu(ca->cpuusage);
78 out_free_ca:
79 kfree(ca);
80 out:
81 return ERR_PTR(-ENOMEM);
82 }
83
84 /* Destroy an existing CPU accounting group */
85 static void cpuacct_css_free(struct cgroup_subsys_state *css)
86 {
87 struct cpuacct *ca = css_ca(css);
88
89 free_percpu(ca->cpustat);
90 free_percpu(ca->cpuusage);
91 kfree(ca);
92 }
93
94 static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
95 enum cpuacct_stat_index index)
96 {
97 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
98 u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
99 u64 data;
100
101 /*
102 * We allow index == CPUACCT_STAT_NSTATS here to read
103 * the sum of usages.
104 */
105 if (WARN_ON_ONCE(index > CPUACCT_STAT_NSTATS))
106 return 0;
107
108 #ifndef CONFIG_64BIT
109 /*
110 * Take rq->lock to make 64-bit read safe on 32-bit platforms.
111 */
112 raw_spin_rq_lock_irq(cpu_rq(cpu));
113 #endif
114
115 switch (index) {
116 case CPUACCT_STAT_USER:
117 data = cpustat[CPUTIME_USER] + cpustat[CPUTIME_NICE];
118 break;
119 case CPUACCT_STAT_SYSTEM:
120 data = cpustat[CPUTIME_SYSTEM] + cpustat[CPUTIME_IRQ] +
121 cpustat[CPUTIME_SOFTIRQ];
122 break;
123 case CPUACCT_STAT_NSTATS:
124 data = *cpuusage;
125 break;
126 }
127
128 #ifndef CONFIG_64BIT
129 raw_spin_rq_unlock_irq(cpu_rq(cpu));
130 #endif
131
132 return data;
133 }
134
135 static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu)
136 {
137 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
138 u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
139
140 /* Don't allow to reset global kernel_cpustat */
141 if (ca == &root_cpuacct)
142 return;
143
144 #ifndef CONFIG_64BIT
145 /*
146 * Take rq->lock to make 64-bit write safe on 32-bit platforms.
147 */
148 raw_spin_rq_lock_irq(cpu_rq(cpu));
149 #endif
150 *cpuusage = 0;
151 cpustat[CPUTIME_USER] = cpustat[CPUTIME_NICE] = 0;
152 cpustat[CPUTIME_SYSTEM] = cpustat[CPUTIME_IRQ] = 0;
153 cpustat[CPUTIME_SOFTIRQ] = 0;
154
155 #ifndef CONFIG_64BIT
156 raw_spin_rq_unlock_irq(cpu_rq(cpu));
157 #endif
158 }
159
160 /* Return total CPU usage (in nanoseconds) of a group */
161 static u64 __cpuusage_read(struct cgroup_subsys_state *css,
162 enum cpuacct_stat_index index)
163 {
164 struct cpuacct *ca = css_ca(css);
165 u64 totalcpuusage = 0;
166 int i;
167
168 for_each_possible_cpu(i)
169 totalcpuusage += cpuacct_cpuusage_read(ca, i, index);
170
171 return totalcpuusage;
172 }
173
174 static u64 cpuusage_user_read(struct cgroup_subsys_state *css,
175 struct cftype *cft)
176 {
177 return __cpuusage_read(css, CPUACCT_STAT_USER);
178 }
179
180 static u64 cpuusage_sys_read(struct cgroup_subsys_state *css,
181 struct cftype *cft)
182 {
183 return __cpuusage_read(css, CPUACCT_STAT_SYSTEM);
184 }
185
186 static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
187 {
188 return __cpuusage_read(css, CPUACCT_STAT_NSTATS);
189 }
190
191 static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
192 u64 val)
193 {
194 struct cpuacct *ca = css_ca(css);
195 int cpu;
196
197 /*
198 * Only allow '' here to do a reset.
199 */
200 if (val)
201 return -EINVAL;
202
203 for_each_possible_cpu(cpu)
204 cpuacct_cpuusage_write(ca, cpu);
205
206 return 0;
207 }
208
209 static int __cpuacct_percpu_seq_show(struct seq_file *m,
210 enum cpuacct_stat_index index)
211 {
212 struct cpuacct *ca = css_ca(seq_css(m));
213 u64 percpu;
214 int i;
215
216 for_each_possible_cpu(i) {
217 percpu = cpuacct_cpuusage_read(ca, i, index);
218 seq_printf(m, "%llu ", (unsigned long long) percpu);
219 }
220 seq_printf(m, "\n");
221 return 0;
222 }
223
224 static int cpuacct_percpu_user_seq_show(struct seq_file *m, void *V)
225 {
226 return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_USER);
227 }
228
229 static int cpuacct_percpu_sys_seq_show(struct seq_file *m, void *V)
230 {
231 return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_SYSTEM);
232 }
233
234 static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
235 {
236 return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_NSTATS);
237 }
238
239 static int cpuacct_all_seq_show(struct seq_file *m, void *V)
240 {
241 struct cpuacct *ca = css_ca(seq_css(m));
242 int index;
243 int cpu;
244
245 seq_puts(m, "cpu");
246 for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
247 seq_printf(m, " %s", cpuacct_stat_desc[index]);
248 seq_puts(m, "\n");
249
250 for_each_possible_cpu(cpu) {
251 seq_printf(m, "%d", cpu);
252 for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
253 seq_printf(m, " %llu",
254 cpuacct_cpuusage_read(ca, cpu, index));
255 seq_puts(m, "\n");
256 }
257 return 0;
258 }
259
260 static int cpuacct_stats_show(struct seq_file *sf, void *v)
261 {
262 struct cpuacct *ca = css_ca(seq_css(sf));
263 struct task_cputime cputime;
264 u64 val[CPUACCT_STAT_NSTATS];
265 int cpu;
266 int stat;
267
268 memset(&cputime, 0, sizeof(cputime));
269 for_each_possible_cpu(cpu) {
270 u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
271
272 cputime.utime += cpustat[CPUTIME_USER];
273 cputime.utime += cpustat[CPUTIME_NICE];
274 cputime.stime += cpustat[CPUTIME_SYSTEM];
275 cputime.stime += cpustat[CPUTIME_IRQ];
276 cputime.stime += cpustat[CPUTIME_SOFTIRQ];
277
278 cputime.sum_exec_runtime += *per_cpu_ptr(ca->cpuusage, cpu);
279 }
280
281 cputime_adjust(&cputime, &seq_css(sf)->cgroup->prev_cputime,
282 &val[CPUACCT_STAT_USER], &val[CPUACCT_STAT_SYSTEM]);
283
284 for (stat = 0; stat < CPUACCT_STAT_NSTATS; stat++) {
285 seq_printf(sf, "%s %llu\n", cpuacct_stat_desc[stat],
286 nsec_to_clock_t(val[stat]));
287 }
288
289 return 0;
290 }
291
292 static struct cftype files[] = {
293 {
294 .name = "usage",
295 .read_u64 = cpuusage_read,
296 .write_u64 = cpuusage_write,
297 },
298 {
299 .name = "usage_user",
300 .read_u64 = cpuusage_user_read,
301 },
302 {
303 .name = "usage_sys",
304 .read_u64 = cpuusage_sys_read,
305 },
306 {
307 .name = "usage_percpu",
308 .seq_show = cpuacct_percpu_seq_show,
309 },
310 {
311 .name = "usage_percpu_user",
312 .seq_show = cpuacct_percpu_user_seq_show,
313 },
314 {
315 .name = "usage_percpu_sys",
316 .seq_show = cpuacct_percpu_sys_seq_show,
317 },
318 {
319 .name = "usage_all",
320 .seq_show = cpuacct_all_seq_show,
321 },
322 {
323 .name = "stat",
324 .seq_show = cpuacct_stats_show,
325 },
326 { } /* terminate */
327 };
328
329 /*
330 * charge this task's execution time to its accounting group.
331 *
332 * called with rq->lock held.
333 */
334 void cpuacct_charge(struct task_struct *tsk, u64 cputime)
335 {
336 unsigned int cpu = task_cpu(tsk);
337 struct cpuacct *ca;
338
339 lockdep_assert_rq_held(cpu_rq(cpu));
340
341 for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
342 *per_cpu_ptr(ca->cpuusage, cpu) += cputime;
343 }
344
345 /*
346 * Add user/system time to cpuacct.
347 *
348 * Note: it's the caller that updates the account of the root cgroup.
349 */
350 void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
351 {
352 struct cpuacct *ca;
353
354 for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
355 __this_cpu_add(ca->cpustat->cpustat[index], val);
356 }
357
358 struct cgroup_subsys cpuacct_cgrp_subsys = {
359 .css_alloc = cpuacct_css_alloc,
360 .css_free = cpuacct_css_free,
361 .legacy_cftypes = files,
362 .early_init = true,
363 };
364
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