xref: /openbmc/linux/kernel/sched/cpuacct.c (revision 3eba0505)
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 
css_ca(struct cgroup_subsys_state * css)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 */
task_ca(struct task_struct * tsk)37 static inline struct cpuacct *task_ca(struct task_struct *tsk)
38 {
39 	return css_ca(task_css(tsk, cpuacct_cgrp_id));
40 }
41 
parent_ca(struct cpuacct * ca)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 *
cpuacct_css_alloc(struct cgroup_subsys_state * parent_css)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 */
cpuacct_css_free(struct cgroup_subsys_state * css)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 
cpuacct_cpuusage_read(struct cpuacct * ca,int cpu,enum cpuacct_stat_index index)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 
cpuacct_cpuusage_write(struct cpuacct * ca,int cpu)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 */
__cpuusage_read(struct cgroup_subsys_state * css,enum cpuacct_stat_index index)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 
cpuusage_user_read(struct cgroup_subsys_state * css,struct cftype * cft)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 
cpuusage_sys_read(struct cgroup_subsys_state * css,struct cftype * cft)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 
cpuusage_read(struct cgroup_subsys_state * css,struct cftype * cft)186 static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
187 {
188 	return __cpuusage_read(css, CPUACCT_STAT_NSTATS);
189 }
190 
cpuusage_write(struct cgroup_subsys_state * css,struct cftype * cft,u64 val)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 '0' 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 
__cpuacct_percpu_seq_show(struct seq_file * m,enum cpuacct_stat_index index)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 
cpuacct_percpu_user_seq_show(struct seq_file * m,void * V)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 
cpuacct_percpu_sys_seq_show(struct seq_file * m,void * V)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 
cpuacct_percpu_seq_show(struct seq_file * m,void * V)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 
cpuacct_all_seq_show(struct seq_file * m,void * V)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 
cpuacct_stats_show(struct seq_file * sf,void * v)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  */
cpuacct_charge(struct task_struct * tsk,u64 cputime)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  */
cpuacct_account_field(struct task_struct * tsk,int index,u64 val)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