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1/* delayacct.c - per-task delay accounting
2 *
3 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it would be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
13 * the GNU General Public License for more details.
14 */
15
16#include <linux/sched.h>
17#include <linux/slab.h>
18#include <linux/taskstats.h>
19#include <linux/time.h>
20#include <linux/sysctl.h>
21#include <linux/delayacct.h>
22#include <linux/module.h>
23
24int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */
25EXPORT_SYMBOL_GPL(delayacct_on);
26struct kmem_cache *delayacct_cache;
27
28static int __init delayacct_setup_disable(char *str)
29{
30 delayacct_on = 0;
31 return 1;
32}
33__setup("nodelayacct", delayacct_setup_disable);
34
35void delayacct_init(void)
36{
37 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC);
38 delayacct_tsk_init(&init_task);
39}
40
41void __delayacct_tsk_init(struct task_struct *tsk)
42{
43 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
44 if (tsk->delays)
45 spin_lock_init(&tsk->delays->lock);
46}
47
48/*
49 * Start accounting for a delay statistic using
50 * its starting timestamp (@start)
51 */
52
53static inline void delayacct_start(struct timespec *start)
54{
55 do_posix_clock_monotonic_gettime(start);
56}
57
58/*
59 * Finish delay accounting for a statistic using
60 * its timestamps (@start, @end), accumalator (@total) and @count
61 */
62
63static void delayacct_end(struct timespec *start, struct timespec *end,
64 u64 *total, u32 *count)
65{
66 struct timespec ts;
67 s64 ns;
68 unsigned long flags;
69
70 do_posix_clock_monotonic_gettime(end);
71 ts = timespec_sub(*end, *start);
72 ns = timespec_to_ns(&ts);
73 if (ns < 0)
74 return;
75
76 spin_lock_irqsave(¤t->delays->lock, flags);
77 *total += ns;
78 (*count)++;
79 spin_unlock_irqrestore(¤t->delays->lock, flags);
80}
81
82void __delayacct_blkio_start(void)
83{
84 delayacct_start(¤t->delays->blkio_start);
85}
86
87void __delayacct_blkio_end(void)
88{
89 if (current->delays->flags & DELAYACCT_PF_SWAPIN)
90 /* Swapin block I/O */
91 delayacct_end(¤t->delays->blkio_start,
92 ¤t->delays->blkio_end,
93 ¤t->delays->swapin_delay,
94 ¤t->delays->swapin_count);
95 else /* Other block I/O */
96 delayacct_end(¤t->delays->blkio_start,
97 ¤t->delays->blkio_end,
98 ¤t->delays->blkio_delay,
99 ¤t->delays->blkio_count);
100}
101
102int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
103{
104 s64 tmp;
105 unsigned long t1;
106 unsigned long long t2, t3;
107 unsigned long flags;
108 struct timespec ts;
109
110 /* Though tsk->delays accessed later, early exit avoids
111 * unnecessary returning of other data
112 */
113 if (!tsk->delays)
114 goto done;
115
116 tmp = (s64)d->cpu_run_real_total;
117 cputime_to_timespec(tsk->utime + tsk->stime, &ts);
118 tmp += timespec_to_ns(&ts);
119 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
120
121 tmp = (s64)d->cpu_scaled_run_real_total;
122 cputime_to_timespec(tsk->utimescaled + tsk->stimescaled, &ts);
123 tmp += timespec_to_ns(&ts);
124 d->cpu_scaled_run_real_total =
125 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
126
127 /*
128 * No locking available for sched_info (and too expensive to add one)
129 * Mitigate by taking snapshot of values
130 */
131 t1 = tsk->sched_info.pcount;
132 t2 = tsk->sched_info.run_delay;
133 t3 = tsk->se.sum_exec_runtime;
134
135 d->cpu_count += t1;
136
137 tmp = (s64)d->cpu_delay_total + t2;
138 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
139
140 tmp = (s64)d->cpu_run_virtual_total + t3;
141 d->cpu_run_virtual_total =
142 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
143
144 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
145
146 spin_lock_irqsave(&tsk->delays->lock, flags);
147 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
148 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
149 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
150 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
151 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
152 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
153 d->blkio_count += tsk->delays->blkio_count;
154 d->swapin_count += tsk->delays->swapin_count;
155 d->freepages_count += tsk->delays->freepages_count;
156 spin_unlock_irqrestore(&tsk->delays->lock, flags);
157
158done:
159 return 0;
160}
161
162__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
163{
164 __u64 ret;
165 unsigned long flags;
166
167 spin_lock_irqsave(&tsk->delays->lock, flags);
168 ret = nsec_to_clock_t(tsk->delays->blkio_delay +
169 tsk->delays->swapin_delay);
170 spin_unlock_irqrestore(&tsk->delays->lock, flags);
171 return ret;
172}
173
174void __delayacct_freepages_start(void)
175{
176 delayacct_start(¤t->delays->freepages_start);
177}
178
179void __delayacct_freepages_end(void)
180{
181 delayacct_end(¤t->delays->freepages_start,
182 ¤t->delays->freepages_end,
183 ¤t->delays->freepages_delay,
184 ¤t->delays->freepages_count);
185}
186
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
47int 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#endif
67
68void __delayacct_tsk_init(struct task_struct *tsk)
69{
70 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
71 if (tsk->delays)
72 raw_spin_lock_init(&tsk->delays->lock);
73}
74
75/*
76 * Finish delay accounting for a statistic using its timestamps (@start),
77 * accumalator (@total) and @count
78 */
79static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count)
80{
81 s64 ns = local_clock() - *start;
82 unsigned long flags;
83
84 if (ns > 0) {
85 raw_spin_lock_irqsave(lock, flags);
86 *total += ns;
87 (*count)++;
88 raw_spin_unlock_irqrestore(lock, flags);
89 }
90}
91
92void __delayacct_blkio_start(void)
93{
94 current->delays->blkio_start = local_clock();
95}
96
97/*
98 * We cannot rely on the `current` macro, as we haven't yet switched back to
99 * the process being woken.
100 */
101void __delayacct_blkio_end(struct task_struct *p)
102{
103 struct task_delay_info *delays = p->delays;
104 u64 *total;
105 u32 *count;
106
107 if (p->delays->flags & DELAYACCT_PF_SWAPIN) {
108 total = &delays->swapin_delay;
109 count = &delays->swapin_count;
110 } else {
111 total = &delays->blkio_delay;
112 count = &delays->blkio_count;
113 }
114
115 delayacct_end(&delays->lock, &delays->blkio_start, total, count);
116}
117
118int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
119{
120 u64 utime, stime, stimescaled, utimescaled;
121 unsigned long long t2, t3;
122 unsigned long flags, t1;
123 s64 tmp;
124
125 task_cputime(tsk, &utime, &stime);
126 tmp = (s64)d->cpu_run_real_total;
127 tmp += utime + stime;
128 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
129
130 task_cputime_scaled(tsk, &utimescaled, &stimescaled);
131 tmp = (s64)d->cpu_scaled_run_real_total;
132 tmp += utimescaled + stimescaled;
133 d->cpu_scaled_run_real_total =
134 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
135
136 /*
137 * No locking available for sched_info (and too expensive to add one)
138 * Mitigate by taking snapshot of values
139 */
140 t1 = tsk->sched_info.pcount;
141 t2 = tsk->sched_info.run_delay;
142 t3 = tsk->se.sum_exec_runtime;
143
144 d->cpu_count += t1;
145
146 tmp = (s64)d->cpu_delay_total + t2;
147 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
148
149 tmp = (s64)d->cpu_run_virtual_total + t3;
150 d->cpu_run_virtual_total =
151 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
152
153 if (!tsk->delays)
154 return 0;
155
156 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
157
158 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
159 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
160 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
161 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
162 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
163 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
164 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
165 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
166 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
167 d->blkio_count += tsk->delays->blkio_count;
168 d->swapin_count += tsk->delays->swapin_count;
169 d->freepages_count += tsk->delays->freepages_count;
170 d->thrashing_count += tsk->delays->thrashing_count;
171 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
172
173 return 0;
174}
175
176__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
177{
178 __u64 ret;
179 unsigned long flags;
180
181 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
182 ret = nsec_to_clock_t(tsk->delays->blkio_delay +
183 tsk->delays->swapin_delay);
184 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
185 return ret;
186}
187
188void __delayacct_freepages_start(void)
189{
190 current->delays->freepages_start = local_clock();
191}
192
193void __delayacct_freepages_end(void)
194{
195 delayacct_end(¤t->delays->lock,
196 ¤t->delays->freepages_start,
197 ¤t->delays->freepages_delay,
198 ¤t->delays->freepages_count);
199}
200
201void __delayacct_thrashing_start(void)
202{
203 current->delays->thrashing_start = local_clock();
204}
205
206void __delayacct_thrashing_end(void)
207{
208 delayacct_end(¤t->delays->lock,
209 ¤t->delays->thrashing_start,
210 ¤t->delays->thrashing_delay,
211 ¤t->delays->thrashing_count);
212}