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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/slab.h> | |
11 | #include <linux/taskstats.h> | |
12 | #include <linux/time.h> | |
13 | #include <linux/sysctl.h> | |
14 | #include <linux/delayacct.h> | |
15 | #include <linux/module.h> | |
16 | ||
17 | int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ | |
18 | EXPORT_SYMBOL_GPL(delayacct_on); | |
19 | struct kmem_cache *delayacct_cache; | |
20 | ||
21 | static int __init delayacct_setup_disable(char *str) | |
22 | { | |
23 | delayacct_on = 0; | |
24 | return 1; | |
25 | } | |
26 | __setup("nodelayacct", delayacct_setup_disable); | |
27 | ||
28 | void delayacct_init(void) | |
29 | { | |
30 | delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT); | |
31 | delayacct_tsk_init(&init_task); | |
32 | } | |
33 | ||
34 | void __delayacct_tsk_init(struct task_struct *tsk) | |
35 | { | |
36 | tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); | |
37 | if (tsk->delays) | |
38 | raw_spin_lock_init(&tsk->delays->lock); | |
39 | } | |
40 | ||
41 | /* | |
42 | * Finish delay accounting for a statistic using its timestamps (@start), | |
43 | * accumalator (@total) and @count | |
44 | */ | |
45 | static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, | |
46 | u32 *count) | |
47 | { | |
48 | s64 ns = ktime_get_ns() - *start; | |
49 | unsigned long flags; | |
50 | ||
51 | if (ns > 0) { | |
52 | raw_spin_lock_irqsave(lock, flags); | |
53 | *total += ns; | |
54 | (*count)++; | |
55 | raw_spin_unlock_irqrestore(lock, flags); | |
56 | } | |
57 | } | |
58 | ||
59 | void __delayacct_blkio_start(void) | |
60 | { | |
61 | current->delays->blkio_start = ktime_get_ns(); | |
62 | } | |
63 | ||
64 | /* | |
65 | * We cannot rely on the `current` macro, as we haven't yet switched back to | |
66 | * the process being woken. | |
67 | */ | |
68 | void __delayacct_blkio_end(struct task_struct *p) | |
69 | { | |
70 | struct task_delay_info *delays = p->delays; | |
71 | u64 *total; | |
72 | u32 *count; | |
73 | ||
74 | if (p->delays->flags & DELAYACCT_PF_SWAPIN) { | |
75 | total = &delays->swapin_delay; | |
76 | count = &delays->swapin_count; | |
77 | } else { | |
78 | total = &delays->blkio_delay; | |
79 | count = &delays->blkio_count; | |
80 | } | |
81 | ||
82 | delayacct_end(&delays->lock, &delays->blkio_start, total, count); | |
83 | } | |
84 | ||
85 | int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) | |
86 | { | |
87 | u64 utime, stime, stimescaled, utimescaled; | |
88 | unsigned long long t2, t3; | |
89 | unsigned long flags, t1; | |
90 | s64 tmp; | |
91 | ||
92 | task_cputime(tsk, &utime, &stime); | |
93 | tmp = (s64)d->cpu_run_real_total; | |
94 | tmp += utime + stime; | |
95 | d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; | |
96 | ||
97 | task_cputime_scaled(tsk, &utimescaled, &stimescaled); | |
98 | tmp = (s64)d->cpu_scaled_run_real_total; | |
99 | tmp += utimescaled + stimescaled; | |
100 | d->cpu_scaled_run_real_total = | |
101 | (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; | |
102 | ||
103 | /* | |
104 | * No locking available for sched_info (and too expensive to add one) | |
105 | * Mitigate by taking snapshot of values | |
106 | */ | |
107 | t1 = tsk->sched_info.pcount; | |
108 | t2 = tsk->sched_info.run_delay; | |
109 | t3 = tsk->se.sum_exec_runtime; | |
110 | ||
111 | d->cpu_count += t1; | |
112 | ||
113 | tmp = (s64)d->cpu_delay_total + t2; | |
114 | d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; | |
115 | ||
116 | tmp = (s64)d->cpu_run_virtual_total + t3; | |
117 | d->cpu_run_virtual_total = | |
118 | (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; | |
119 | ||
120 | /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ | |
121 | ||
122 | raw_spin_lock_irqsave(&tsk->delays->lock, flags); | |
123 | tmp = d->blkio_delay_total + tsk->delays->blkio_delay; | |
124 | d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; | |
125 | tmp = d->swapin_delay_total + tsk->delays->swapin_delay; | |
126 | d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; | |
127 | tmp = d->freepages_delay_total + tsk->delays->freepages_delay; | |
128 | d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; | |
129 | tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay; | |
130 | d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp; | |
131 | d->blkio_count += tsk->delays->blkio_count; | |
132 | d->swapin_count += tsk->delays->swapin_count; | |
133 | d->freepages_count += tsk->delays->freepages_count; | |
134 | d->thrashing_count += tsk->delays->thrashing_count; | |
135 | raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); | |
136 | ||
137 | return 0; | |
138 | } | |
139 | ||
140 | __u64 __delayacct_blkio_ticks(struct task_struct *tsk) | |
141 | { | |
142 | __u64 ret; | |
143 | unsigned long flags; | |
144 | ||
145 | raw_spin_lock_irqsave(&tsk->delays->lock, flags); | |
146 | ret = nsec_to_clock_t(tsk->delays->blkio_delay + | |
147 | tsk->delays->swapin_delay); | |
148 | raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); | |
149 | return ret; | |
150 | } | |
151 | ||
152 | void __delayacct_freepages_start(void) | |
153 | { | |
154 | current->delays->freepages_start = ktime_get_ns(); | |
155 | } | |
156 | ||
157 | void __delayacct_freepages_end(void) | |
158 | { | |
159 | delayacct_end( | |
160 | ¤t->delays->lock, | |
161 | ¤t->delays->freepages_start, | |
162 | ¤t->delays->freepages_delay, | |
163 | ¤t->delays->freepages_count); | |
164 | } | |
165 | ||
166 | void __delayacct_thrashing_start(void) | |
167 | { | |
168 | current->delays->thrashing_start = ktime_get_ns(); | |
169 | } | |
170 | ||
171 | void __delayacct_thrashing_end(void) | |
172 | { | |
173 | delayacct_end(¤t->delays->lock, | |
174 | ¤t->delays->thrashing_start, | |
175 | ¤t->delays->thrashing_delay, | |
176 | ¤t->delays->thrashing_count); | |
177 | } |