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(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 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 * accumalator (@total) and @count
97 */
98static 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
111void __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 */
120void __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
128int 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
206void __delayacct_freepages_start(void)
207{
208	current->delays->freepages_start = local_clock();
209}
210
211void __delayacct_freepages_end(void)
212{
213	delayacct_end(&current->delays->lock,
214		      &current->delays->freepages_start,
215		      &current->delays->freepages_delay,
216		      &current->delays->freepages_count);
217}
218
219void __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
229void __delayacct_thrashing_end(bool *in_thrashing)
230{
231	if (*in_thrashing)
232		return;
233
234	current->in_thrashing = 0;
235	delayacct_end(&current->delays->lock,
236		      &current->delays->thrashing_start,
237		      &current->delays->thrashing_delay,
238		      &current->delays->thrashing_count);
239}
240
241void __delayacct_swapin_start(void)
242{
243	current->delays->swapin_start = local_clock();
244}
245
246void __delayacct_swapin_end(void)
247{
248	delayacct_end(&current->delays->lock,
249		      &current->delays->swapin_start,
250		      &current->delays->swapin_delay,
251		      &current->delays->swapin_count);
252}
253
254void __delayacct_compact_start(void)
255{
256	current->delays->compact_start = local_clock();
257}
258
259void __delayacct_compact_end(void)
260{
261	delayacct_end(&current->delays->lock,
262		      &current->delays->compact_start,
263		      &current->delays->compact_delay,
264		      &current->delays->compact_count);
265}
266
267void __delayacct_wpcopy_start(void)
268{
269	current->delays->wpcopy_start = local_clock();
270}
271
272void __delayacct_wpcopy_end(void)
273{
274	delayacct_end(&current->delays->lock,
275		      &current->delays->wpcopy_start,
276		      &current->delays->wpcopy_delay,
277		      &current->delays->wpcopy_count);
278}
279
280void __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