projects/linux·blob 2c455ddc · refs

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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 UPDATE_DELAY(type) \
18do { \
19 d->type##_delay_max = tsk->delays->type##_delay_max; \
20 d->type##_delay_min = tsk->delays->type##_delay_min; \
21 d->type##_delay_max_ts.tv_sec = tsk->delays->type##_delay_max_ts.tv_sec; \
22 d->type##_delay_max_ts.tv_nsec = tsk->delays->type##_delay_max_ts.tv_nsec; \
23 tmp = d->type##_delay_total + tsk->delays->type##_delay; \
24 d->type##_delay_total = (tmp < d->type##_delay_total) ? 0 : tmp; \
25 d->type##_count += tsk->delays->type##_count; \
26} while (0)
27
28DEFINE_STATIC_KEY_FALSE(delayacct_key);
29int delayacct_on __read_mostly; /* Delay accounting turned on/off */
30struct kmem_cache *delayacct_cache;
31
32static void set_delayacct(bool enabled)
33{
34 if (enabled) {
35 static_branch_enable(&delayacct_key);
36 delayacct_on = 1;
37 } else {
38 delayacct_on = 0;
39 static_branch_disable(&delayacct_key);
40 }
41}
42
43static int __init delayacct_setup_enable(char *str)
44{
45 delayacct_on = 1;
46 return 1;
47}
48__setup("delayacct", delayacct_setup_enable);
49
50void delayacct_init(void)
51{
52 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
53 delayacct_tsk_init(&init_task);
54 set_delayacct(delayacct_on);
55}
56
57#ifdef CONFIG_SYSCTL
58static int sysctl_delayacct(const struct ctl_table *table, int write, void *buffer,
59 size_t *lenp, loff_t *ppos)
60{
61 int state = delayacct_on;
62 struct ctl_table t;
63 int err;
64
65 if (write && !capable(CAP_SYS_ADMIN))
66 return -EPERM;
67
68 t = *table;
69 t.data = &state;
70 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
71 if (err < 0)
72 return err;
73 if (write)
74 set_delayacct(state);
75 return err;
76}
77
78static const struct ctl_table kern_delayacct_table[] = {
79 {
80 .procname = "task_delayacct",
81 .data = NULL,
82 .maxlen = sizeof(unsigned int),
83 .mode = 0644,
84 .proc_handler = sysctl_delayacct,
85 .extra1 = SYSCTL_ZERO,
86 .extra2 = SYSCTL_ONE,
87 },
88};
89
90static __init int kernel_delayacct_sysctls_init(void)
91{
92 register_sysctl_init("kernel", kern_delayacct_table);
93 return 0;
94}
95late_initcall(kernel_delayacct_sysctls_init);
96#endif
97
98void __delayacct_tsk_init(struct task_struct *tsk)
99{
100 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
101 if (tsk->delays)
102 raw_spin_lock_init(&tsk->delays->lock);
103}
104
105/*
106 * Finish delay accounting for a statistic using its timestamps (@start),
107 * accumulator (@total) and @count
108 */
109static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count,
110 u64 *max, u64 *min, struct timespec64 *ts)
111{
112 s64 ns = local_clock() - *start;
113 unsigned long flags;
114
115 if (ns > 0) {
116 raw_spin_lock_irqsave(lock, flags);
117 *total += ns;
118 (*count)++;
119 if (ns > *max) {
120 *max = ns;
121 ktime_get_real_ts64(ts);
122 }
123 if (*min == 0 || ns < *min)
124 *min = ns;
125 raw_spin_unlock_irqrestore(lock, flags);
126 }
127}
128
129void __delayacct_blkio_start(void)
130{
131 current->delays->blkio_start = local_clock();
132}
133
134/*
135 * We cannot rely on the `current` macro, as we haven't yet switched back to
136 * the process being woken.
137 */
138void __delayacct_blkio_end(struct task_struct *p)
139{
140 delayacct_end(&p->delays->lock,
141 &p->delays->blkio_start,
142 &p->delays->blkio_delay,
143 &p->delays->blkio_count,
144 &p->delays->blkio_delay_max,
145 &p->delays->blkio_delay_min,
146 &p->delays->blkio_delay_max_ts);
147}
148
149int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
150{
151 u64 utime, stime, stimescaled, utimescaled;
152 unsigned long long t2, t3;
153 unsigned long flags, t1;
154 s64 tmp;
155
156 task_cputime(tsk, &utime, &stime);
157 tmp = (s64)d->cpu_run_real_total;
158 tmp += utime + stime;
159 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
160
161 task_cputime_scaled(tsk, &utimescaled, &stimescaled);
162 tmp = (s64)d->cpu_scaled_run_real_total;
163 tmp += utimescaled + stimescaled;
164 d->cpu_scaled_run_real_total =
165 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
166
167 /*
168 * No locking available for sched_info (and too expensive to add one)
169 * Mitigate by taking snapshot of values
170 */
171 t1 = tsk->sched_info.pcount;
172 t2 = tsk->sched_info.run_delay;
173 t3 = tsk->se.sum_exec_runtime;
174
175 d->cpu_count += t1;
176
177 d->cpu_delay_max = tsk->sched_info.max_run_delay;
178 d->cpu_delay_min = tsk->sched_info.min_run_delay;
179 d->cpu_delay_max_ts.tv_sec = tsk->sched_info.max_run_delay_ts.tv_sec;
180 d->cpu_delay_max_ts.tv_nsec = tsk->sched_info.max_run_delay_ts.tv_nsec;
181 tmp = (s64)d->cpu_delay_total + t2;
182 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
183 tmp = (s64)d->cpu_run_virtual_total + t3;
184
185 d->cpu_run_virtual_total =
186 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
187
188 if (!tsk->delays)
189 return 0;
190
191 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
192 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
193 UPDATE_DELAY(blkio);
194 UPDATE_DELAY(swapin);
195 UPDATE_DELAY(freepages);
196 UPDATE_DELAY(thrashing);
197 UPDATE_DELAY(compact);
198 UPDATE_DELAY(wpcopy);
199 UPDATE_DELAY(irq);
200 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
201
202 return 0;
203}
204
205__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
206{
207 __u64 ret;
208 unsigned long flags;
209
210 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
211 ret = nsec_to_clock_t(tsk->delays->blkio_delay);
212 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
213 return ret;
214}
215
216void __delayacct_freepages_start(void)
217{
218 current->delays->freepages_start = local_clock();
219}
220
221void __delayacct_freepages_end(void)
222{
223 delayacct_end(&current->delays->lock,
224 &current->delays->freepages_start,
225 &current->delays->freepages_delay,
226 &current->delays->freepages_count,
227 &current->delays->freepages_delay_max,
228 &current->delays->freepages_delay_min,
229 &current->delays->freepages_delay_max_ts);
230}
231
232void __delayacct_thrashing_start(bool *in_thrashing)
233{
234 *in_thrashing = !!current->in_thrashing;
235 if (*in_thrashing)
236 return;
237
238 current->in_thrashing = 1;
239 current->delays->thrashing_start = local_clock();
240}
241
242void __delayacct_thrashing_end(bool *in_thrashing)
243{
244 if (*in_thrashing)
245 return;
246
247 current->in_thrashing = 0;
248 delayacct_end(&current->delays->lock,
249 &current->delays->thrashing_start,
250 &current->delays->thrashing_delay,
251 &current->delays->thrashing_count,
252 &current->delays->thrashing_delay_max,
253 &current->delays->thrashing_delay_min,
254 &current->delays->thrashing_delay_max_ts);
255}
256
257void __delayacct_swapin_start(void)
258{
259 current->delays->swapin_start = local_clock();
260}
261
262void __delayacct_swapin_end(void)
263{
264 delayacct_end(&current->delays->lock,
265 &current->delays->swapin_start,
266 &current->delays->swapin_delay,
267 &current->delays->swapin_count,
268 &current->delays->swapin_delay_max,
269 &current->delays->swapin_delay_min,
270 &current->delays->swapin_delay_max_ts);
271}
272
273void __delayacct_compact_start(void)
274{
275 current->delays->compact_start = local_clock();
276}
277
278void __delayacct_compact_end(void)
279{
280 delayacct_end(&current->delays->lock,
281 &current->delays->compact_start,
282 &current->delays->compact_delay,
283 &current->delays->compact_count,
284 &current->delays->compact_delay_max,
285 &current->delays->compact_delay_min,
286 &current->delays->compact_delay_max_ts);
287}
288
289void __delayacct_wpcopy_start(void)
290{
291 current->delays->wpcopy_start = local_clock();
292}
293
294void __delayacct_wpcopy_end(void)
295{
296 delayacct_end(&current->delays->lock,
297 &current->delays->wpcopy_start,
298 &current->delays->wpcopy_delay,
299 &current->delays->wpcopy_count,
300 &current->delays->wpcopy_delay_max,
301 &current->delays->wpcopy_delay_min,
302 &current->delays->wpcopy_delay_max_ts);
303}
304
305void __delayacct_irq(struct task_struct *task, u32 delta)
306{
307 unsigned long flags;
308
309 raw_spin_lock_irqsave(&task->delays->lock, flags);
310 task->delays->irq_delay += delta;
311 task->delays->irq_count++;
312 if (delta > task->delays->irq_delay_max) {
313 task->delays->irq_delay_max = delta;
314 ktime_get_real_ts64(&task->delays->irq_delay_max_ts);
315 }
316 if (delta && (!task->delays->irq_delay_min || delta < task->delays->irq_delay_min))
317 task->delays->irq_delay_min = delta;
318 raw_spin_unlock_irqrestore(&task->delays->lock, flags);
319}
320