Linux 5.2-rc4
[sfrench/cifs-2.6.git] / kernel / delayacct.c
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/sched/task.h>
18 #include <linux/sched/cputime.h>
19 #include <linux/slab.h>
20 #include <linux/taskstats.h>
21 #include <linux/time.h>
22 #include <linux/sysctl.h>
23 #include <linux/delayacct.h>
24 #include <linux/module.h>
25
26 int delayacct_on __read_mostly = 1;     /* Delay accounting turned on/off */
27 EXPORT_SYMBOL_GPL(delayacct_on);
28 struct kmem_cache *delayacct_cache;
29
30 static int __init delayacct_setup_disable(char *str)
31 {
32         delayacct_on = 0;
33         return 1;
34 }
35 __setup("nodelayacct", delayacct_setup_disable);
36
37 void delayacct_init(void)
38 {
39         delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
40         delayacct_tsk_init(&init_task);
41 }
42
43 void __delayacct_tsk_init(struct task_struct *tsk)
44 {
45         tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
46         if (tsk->delays)
47                 raw_spin_lock_init(&tsk->delays->lock);
48 }
49
50 /*
51  * Finish delay accounting for a statistic using its timestamps (@start),
52  * accumalator (@total) and @count
53  */
54 static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total,
55                           u32 *count)
56 {
57         s64 ns = ktime_get_ns() - *start;
58         unsigned long flags;
59
60         if (ns > 0) {
61                 raw_spin_lock_irqsave(lock, flags);
62                 *total += ns;
63                 (*count)++;
64                 raw_spin_unlock_irqrestore(lock, flags);
65         }
66 }
67
68 void __delayacct_blkio_start(void)
69 {
70         current->delays->blkio_start = ktime_get_ns();
71 }
72
73 /*
74  * We cannot rely on the `current` macro, as we haven't yet switched back to
75  * the process being woken.
76  */
77 void __delayacct_blkio_end(struct task_struct *p)
78 {
79         struct task_delay_info *delays = p->delays;
80         u64 *total;
81         u32 *count;
82
83         if (p->delays->flags & DELAYACCT_PF_SWAPIN) {
84                 total = &delays->swapin_delay;
85                 count = &delays->swapin_count;
86         } else {
87                 total = &delays->blkio_delay;
88                 count = &delays->blkio_count;
89         }
90
91         delayacct_end(&delays->lock, &delays->blkio_start, total, count);
92 }
93
94 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
95 {
96         u64 utime, stime, stimescaled, utimescaled;
97         unsigned long long t2, t3;
98         unsigned long flags, t1;
99         s64 tmp;
100
101         task_cputime(tsk, &utime, &stime);
102         tmp = (s64)d->cpu_run_real_total;
103         tmp += utime + stime;
104         d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
105
106         task_cputime_scaled(tsk, &utimescaled, &stimescaled);
107         tmp = (s64)d->cpu_scaled_run_real_total;
108         tmp += utimescaled + stimescaled;
109         d->cpu_scaled_run_real_total =
110                 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
111
112         /*
113          * No locking available for sched_info (and too expensive to add one)
114          * Mitigate by taking snapshot of values
115          */
116         t1 = tsk->sched_info.pcount;
117         t2 = tsk->sched_info.run_delay;
118         t3 = tsk->se.sum_exec_runtime;
119
120         d->cpu_count += t1;
121
122         tmp = (s64)d->cpu_delay_total + t2;
123         d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
124
125         tmp = (s64)d->cpu_run_virtual_total + t3;
126         d->cpu_run_virtual_total =
127                 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
128
129         /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
130
131         raw_spin_lock_irqsave(&tsk->delays->lock, flags);
132         tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
133         d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
134         tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
135         d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
136         tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
137         d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
138         tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
139         d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
140         d->blkio_count += tsk->delays->blkio_count;
141         d->swapin_count += tsk->delays->swapin_count;
142         d->freepages_count += tsk->delays->freepages_count;
143         d->thrashing_count += tsk->delays->thrashing_count;
144         raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
145
146         return 0;
147 }
148
149 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
150 {
151         __u64 ret;
152         unsigned long flags;
153
154         raw_spin_lock_irqsave(&tsk->delays->lock, flags);
155         ret = nsec_to_clock_t(tsk->delays->blkio_delay +
156                                 tsk->delays->swapin_delay);
157         raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
158         return ret;
159 }
160
161 void __delayacct_freepages_start(void)
162 {
163         current->delays->freepages_start = ktime_get_ns();
164 }
165
166 void __delayacct_freepages_end(void)
167 {
168         delayacct_end(
169                 &current->delays->lock,
170                 &current->delays->freepages_start,
171                 &current->delays->freepages_delay,
172                 &current->delays->freepages_count);
173 }
174
175 void __delayacct_thrashing_start(void)
176 {
177         current->delays->thrashing_start = ktime_get_ns();
178 }
179
180 void __delayacct_thrashing_end(void)
181 {
182         delayacct_end(&current->delays->lock,
183                       &current->delays->thrashing_start,
184                       &current->delays->thrashing_delay,
185                       &current->delays->thrashing_count);
186 }