1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* delayacct.c - per-task delay accounting
3 *
4 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
5 */
6
7 #include <linux/sched.h>
8 #include <linux/sched/task.h>
9 #include <linux/sched/cputime.h>
10 #include <linux/sched/clock.h>
11 #include <linux/slab.h>
12 #include <linux/taskstats.h>
13 #include <linux/sysctl.h>
14 #include <linux/delayacct.h>
15 #include <linux/module.h>
16
17 DEFINE_STATIC_KEY_FALSE(delayacct_key);
18 int delayacct_on __read_mostly; /* Delay accounting turned on/off */
19 struct kmem_cache *delayacct_cache;
20
21 static void set_delayacct(bool enabled)
22 {
23 if (enabled) {
24 static_branch_enable(&delayacct_key);
25 delayacct_on = 1;
26 } else {
27 delayacct_on = 0;
28 static_branch_disable(&delayacct_key);
29 }
30 }
31
32 static int __init delayacct_setup_enable(char *str)
33 {
34 delayacct_on = 1;
35 return 1;
36 }
37 __setup("delayacct", delayacct_setup_enable);
38
39 void delayacct_init(void)
40 {
41 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
42 delayacct_tsk_init(&init_task);
43 set_delayacct(delayacct_on);
44 }
45
46 #ifdef CONFIG_PROC_SYSCTL
47 static int sysctl_delayacct(const struct ctl_table *table, int write, void *buffer,
48 size_t *lenp, loff_t *ppos)
49 {
50 int state = delayacct_on;
51 struct ctl_table t;
52 int err;
53
54 if (write && !capable(CAP_SYS_ADMIN))
55 return -EPERM;
56
57 t = *table;
58 t.data = &state;
59 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
60 if (err < 0)
61 return err;
62 if (write)
63 set_delayacct(state);
64 return err;
65 }
66
67 static struct ctl_table kern_delayacct_table[] = {
68 {
69 .procname = "task_delayacct",
70 .data = NULL,
71 .maxlen = sizeof(unsigned int),
72 .mode = 0644,
73 .proc_handler = sysctl_delayacct,
74 .extra1 = SYSCTL_ZERO,
75 .extra2 = SYSCTL_ONE,
76 },
77 };
78
79 static __init int kernel_delayacct_sysctls_init(void)
80 {
81 register_sysctl_init("kernel", kern_delayacct_table);
82 return 0;
83 }
84 late_initcall(kernel_delayacct_sysctls_init);
85 #endif
86
87 void __delayacct_tsk_init(struct task_struct *tsk)
88 {
89 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
90 if (tsk->delays)
91 raw_spin_lock_init(&tsk->delays->lock);
92 }
93
94 /*
95 * Finish delay accounting for a statistic using its timestamps (@start),
96 * accumalator (@total) and @count
97 */
98 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count)
99 {
100 s64 ns = local_clock() - *start;
101 unsigned long flags;
102
103 if (ns > 0) {
104 raw_spin_lock_irqsave(lock, flags);
105 *total += ns;
106 (*count)++;
107 raw_spin_unlock_irqrestore(lock, flags);
108 }
109 }
110
111 void __delayacct_blkio_start(void)
112 {
113 current->delays->blkio_start = local_clock();
114 }
115
116 /*
117 * We cannot rely on the `current` macro, as we haven't yet switched back to
118 * the process being woken.
119 */
120 void __delayacct_blkio_end(struct task_struct *p)
121 {
122 delayacct_end(&p->delays->lock,
123 &p->delays->blkio_start,
124 &p->delays->blkio_delay,
125 &p->delays->blkio_count);
126 }
127
128 int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
129 {
130 u64 utime, stime, stimescaled, utimescaled;
131 unsigned long long t2, t3;
132 unsigned long flags, t1;
133 s64 tmp;
134
135 task_cputime(tsk, &utime, &stime);
136 tmp = (s64)d->cpu_run_real_total;
137 tmp += utime + stime;
138 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
139
140 task_cputime_scaled(tsk, &utimescaled, &stimescaled);
141 tmp = (s64)d->cpu_scaled_run_real_total;
142 tmp += utimescaled + stimescaled;
143 d->cpu_scaled_run_real_total =
144 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
145
146 /*
147 * No locking available for sched_info (and too expensive to add one)
148 * Mitigate by taking snapshot of values
149 */
150 t1 = tsk->sched_info.pcount;
151 t2 = tsk->sched_info.run_delay;
152 t3 = tsk->se.sum_exec_runtime;
153
154 d->cpu_count += t1;
155
156 tmp = (s64)d->cpu_delay_total + t2;
157 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
158
159 tmp = (s64)d->cpu_run_virtual_total + t3;
160 d->cpu_run_virtual_total =
161 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
162
163 if (!tsk->delays)
164 return 0;
165
166 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
167
168 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
169 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
170 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
171 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
172 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
173 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
174 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
175 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
176 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
177 tmp = d->compact_delay_total + tsk->delays->compact_delay;
178 d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
179 tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;
180 d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp;
181 tmp = d->irq_delay_total + tsk->delays->irq_delay;
182 d->irq_delay_total = (tmp < d->irq_delay_total) ? 0 : tmp;
183 d->blkio_count += tsk->delays->blkio_count;
184 d->swapin_count += tsk->delays->swapin_count;
185 d->freepages_count += tsk->delays->freepages_count;
186 d->thrashing_count += tsk->delays->thrashing_count;
187 d->compact_count += tsk->delays->compact_count;
188 d->wpcopy_count += tsk->delays->wpcopy_count;
189 d->irq_count += tsk->delays->irq_count;
190 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
191
192 return 0;
193 }
194
195 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
196 {
197 __u64 ret;
198 unsigned long flags;
199
200 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
201 ret = nsec_to_clock_t(tsk->delays->blkio_delay);
202 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
203 return ret;
204 }
205
206 void __delayacct_freepages_start(void)
207 {
208 current->delays->freepages_start = local_clock();
209 }
210
211 void __delayacct_freepages_end(void)
212 {
213 delayacct_end(¤t->delays->lock,
214 ¤t->delays->freepages_start,
215 ¤t->delays->freepages_delay,
216 ¤t->delays->freepages_count);
217 }
218
219 void __delayacct_thrashing_start(bool *in_thrashing)
220 {
221 *in_thrashing = !!current->in_thrashing;
222 if (*in_thrashing)
223 return;
224
225 current->in_thrashing = 1;
226 current->delays->thrashing_start = local_clock();
227 }
228
229 void __delayacct_thrashing_end(bool *in_thrashing)
230 {
231 if (*in_thrashing)
232 return;
233
234 current->in_thrashing = 0;
235 delayacct_end(¤t->delays->lock,
236 ¤t->delays->thrashing_start,
237 ¤t->delays->thrashing_delay,
238 ¤t->delays->thrashing_count);
239 }
240
241 void __delayacct_swapin_start(void)
242 {
243 current->delays->swapin_start = local_clock();
244 }
245
246 void __delayacct_swapin_end(void)
247 {
248 delayacct_end(¤t->delays->lock,
249 ¤t->delays->swapin_start,
250 ¤t->delays->swapin_delay,
251 ¤t->delays->swapin_count);
252 }
253
254 void __delayacct_compact_start(void)
255 {
256 current->delays->compact_start = local_clock();
257 }
258
259 void __delayacct_compact_end(void)
260 {
261 delayacct_end(¤t->delays->lock,
262 ¤t->delays->compact_start,
263 ¤t->delays->compact_delay,
264 ¤t->delays->compact_count);
265 }
266
267 void __delayacct_wpcopy_start(void)
268 {
269 current->delays->wpcopy_start = local_clock();
270 }
271
272 void __delayacct_wpcopy_end(void)
273 {
274 delayacct_end(¤t->delays->lock,
275 ¤t->delays->wpcopy_start,
276 ¤t->delays->wpcopy_delay,
277 ¤t->delays->wpcopy_count);
278 }
279
280 void __delayacct_irq(struct task_struct *task, u32 delta)
281 {
282 unsigned long flags;
283
284 raw_spin_lock_irqsave(&task->delays->lock, flags);
285 task->delays->irq_delay += delta;
286 task->delays->irq_count++;
287 raw_spin_unlock_irqrestore(&task->delays->lock, flags);
288 }
289
290
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