projects/linux·blob v6.15-rc7 · refs

324 lines · 9.1 KiB

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
17DEFINE_STATIC_KEY_FALSE(delayacct_key);
18int delayacct_on __read_mostly; /* Delay accounting turned on/off */
19struct kmem_cache *delayacct_cache;
20
21static 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
32static int __init delayacct_setup_enable(char *str)
33{
34 delayacct_on = 1;
35 return 1;
36}
37__setup("delayacct", delayacct_setup_enable);
38
39void 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
47static 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
67static const 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
79static __init int kernel_delayacct_sysctls_init(void)
80{
81 register_sysctl_init("kernel", kern_delayacct_table);
82 return 0;
83}
84late_initcall(kernel_delayacct_sysctls_init);
85#endif
86
87void __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 * accumulator (@total) and @count
97 */
98static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count, u64 *max, u64 *min)
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 if (ns > *max)
108 *max = ns;
109 if (*min == 0 || ns < *min)
110 *min = ns;
111 raw_spin_unlock_irqrestore(lock, flags);
112 }
113}
114
115void __delayacct_blkio_start(void)
116{
117 current->delays->blkio_start = local_clock();
118}
119
120/*
121 * We cannot rely on the `current` macro, as we haven't yet switched back to
122 * the process being woken.
123 */
124void __delayacct_blkio_end(struct task_struct *p)
125{
126 delayacct_end(&p->delays->lock,
127 &p->delays->blkio_start,
128 &p->delays->blkio_delay,
129 &p->delays->blkio_count,
130 &p->delays->blkio_delay_max,
131 &p->delays->blkio_delay_min);
132}
133
134int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
135{
136 u64 utime, stime, stimescaled, utimescaled;
137 unsigned long long t2, t3;
138 unsigned long flags, t1;
139 s64 tmp;
140
141 task_cputime(tsk, &utime, &stime);
142 tmp = (s64)d->cpu_run_real_total;
143 tmp += utime + stime;
144 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
145
146 task_cputime_scaled(tsk, &utimescaled, &stimescaled);
147 tmp = (s64)d->cpu_scaled_run_real_total;
148 tmp += utimescaled + stimescaled;
149 d->cpu_scaled_run_real_total =
150 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
151
152 /*
153 * No locking available for sched_info (and too expensive to add one)
154 * Mitigate by taking snapshot of values
155 */
156 t1 = tsk->sched_info.pcount;
157 t2 = tsk->sched_info.run_delay;
158 t3 = tsk->se.sum_exec_runtime;
159
160 d->cpu_count += t1;
161
162 d->cpu_delay_max = tsk->sched_info.max_run_delay;
163 d->cpu_delay_min = tsk->sched_info.min_run_delay;
164 tmp = (s64)d->cpu_delay_total + t2;
165 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
166 tmp = (s64)d->cpu_run_virtual_total + t3;
167
168 d->cpu_run_virtual_total =
169 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
170
171 if (!tsk->delays)
172 return 0;
173
174 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
175 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
176 d->blkio_delay_max = tsk->delays->blkio_delay_max;
177 d->blkio_delay_min = tsk->delays->blkio_delay_min;
178 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
179 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
180 d->swapin_delay_max = tsk->delays->swapin_delay_max;
181 d->swapin_delay_min = tsk->delays->swapin_delay_min;
182 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
183 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
184 d->freepages_delay_max = tsk->delays->freepages_delay_max;
185 d->freepages_delay_min = tsk->delays->freepages_delay_min;
186 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
187 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
188 d->thrashing_delay_max = tsk->delays->thrashing_delay_max;
189 d->thrashing_delay_min = tsk->delays->thrashing_delay_min;
190 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
191 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
192 d->compact_delay_max = tsk->delays->compact_delay_max;
193 d->compact_delay_min = tsk->delays->compact_delay_min;
194 tmp = d->compact_delay_total + tsk->delays->compact_delay;
195 d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
196 d->wpcopy_delay_max = tsk->delays->wpcopy_delay_max;
197 d->wpcopy_delay_min = tsk->delays->wpcopy_delay_min;
198 tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;
199 d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp;
200 d->irq_delay_max = tsk->delays->irq_delay_max;
201 d->irq_delay_min = tsk->delays->irq_delay_min;
202 tmp = d->irq_delay_total + tsk->delays->irq_delay;
203 d->irq_delay_total = (tmp < d->irq_delay_total) ? 0 : tmp;
204 d->blkio_count += tsk->delays->blkio_count;
205 d->swapin_count += tsk->delays->swapin_count;
206 d->freepages_count += tsk->delays->freepages_count;
207 d->thrashing_count += tsk->delays->thrashing_count;
208 d->compact_count += tsk->delays->compact_count;
209 d->wpcopy_count += tsk->delays->wpcopy_count;
210 d->irq_count += tsk->delays->irq_count;
211 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
212
213 return 0;
214}
215
216__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
217{
218 __u64 ret;
219 unsigned long flags;
220
221 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
222 ret = nsec_to_clock_t(tsk->delays->blkio_delay);
223 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
224 return ret;
225}
226
227void __delayacct_freepages_start(void)
228{
229 current->delays->freepages_start = local_clock();
230}
231
232void __delayacct_freepages_end(void)
233{
234 delayacct_end(&current->delays->lock,
235 &current->delays->freepages_start,
236 &current->delays->freepages_delay,
237 &current->delays->freepages_count,
238 &current->delays->freepages_delay_max,
239 &current->delays->freepages_delay_min);
240}
241
242void __delayacct_thrashing_start(bool *in_thrashing)
243{
244 *in_thrashing = !!current->in_thrashing;
245 if (*in_thrashing)
246 return;
247
248 current->in_thrashing = 1;
249 current->delays->thrashing_start = local_clock();
250}
251
252void __delayacct_thrashing_end(bool *in_thrashing)
253{
254 if (*in_thrashing)
255 return;
256
257 current->in_thrashing = 0;
258 delayacct_end(&current->delays->lock,
259 &current->delays->thrashing_start,
260 &current->delays->thrashing_delay,
261 &current->delays->thrashing_count,
262 &current->delays->thrashing_delay_max,
263 &current->delays->thrashing_delay_min);
264}
265
266void __delayacct_swapin_start(void)
267{
268 current->delays->swapin_start = local_clock();
269}
270
271void __delayacct_swapin_end(void)
272{
273 delayacct_end(&current->delays->lock,
274 &current->delays->swapin_start,
275 &current->delays->swapin_delay,
276 &current->delays->swapin_count,
277 &current->delays->swapin_delay_max,
278 &current->delays->swapin_delay_min);
279}
280
281void __delayacct_compact_start(void)
282{
283 current->delays->compact_start = local_clock();
284}
285
286void __delayacct_compact_end(void)
287{
288 delayacct_end(&current->delays->lock,
289 &current->delays->compact_start,
290 &current->delays->compact_delay,
291 &current->delays->compact_count,
292 &current->delays->compact_delay_max,
293 &current->delays->compact_delay_min);
294}
295
296void __delayacct_wpcopy_start(void)
297{
298 current->delays->wpcopy_start = local_clock();
299}
300
301void __delayacct_wpcopy_end(void)
302{
303 delayacct_end(&current->delays->lock,
304 &current->delays->wpcopy_start,
305 &current->delays->wpcopy_delay,
306 &current->delays->wpcopy_count,
307 &current->delays->wpcopy_delay_max,
308 &current->delays->wpcopy_delay_min);
309}
310
311void __delayacct_irq(struct task_struct *task, u32 delta)
312{
313 unsigned long flags;
314
315 raw_spin_lock_irqsave(&task->delays->lock, flags);
316 task->delays->irq_delay += delta;
317 task->delays->irq_count++;
318 if (delta > task->delays->irq_delay_max)
319 task->delays->irq_delay_max = delta;
320 if (delta && (!task->delays->irq_delay_min || delta < task->delays->irq_delay_min))
321 task->delays->irq_delay_min = delta;
322 raw_spin_unlock_irqrestore(&task->delays->lock, flags);
323}
324