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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/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 | 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(spinlock_t *lock, u64 *start, u64 *total, u32 *count) | |
55 | { | |
56 | s64 ns = ktime_get_ns() - *start; | |
57 | unsigned long flags; | |
58 | ||
59 | if (ns > 0) { | |
60 | spin_lock_irqsave(lock, flags); | |
61 | *total += ns; | |
62 | (*count)++; | |
63 | spin_unlock_irqrestore(lock, flags); | |
64 | } | |
65 | } | |
66 | ||
67 | void __delayacct_blkio_start(void) | |
68 | { | |
69 | current->delays->blkio_start = ktime_get_ns(); | |
70 | } | |
71 | ||
72 | /* | |
73 | * We cannot rely on the `current` macro, as we haven't yet switched back to | |
74 | * the process being woken. | |
75 | */ | |
76 | void __delayacct_blkio_end(struct task_struct *p) | |
77 | { | |
78 | struct task_delay_info *delays = p->delays; | |
79 | u64 *total; | |
80 | u32 *count; | |
81 | ||
82 | if (p->delays->flags & DELAYACCT_PF_SWAPIN) { | |
83 | total = &delays->swapin_delay; | |
84 | count = &delays->swapin_count; | |
85 | } else { | |
86 | total = &delays->blkio_delay; | |
87 | count = &delays->blkio_count; | |
88 | } | |
89 | ||
90 | delayacct_end(&delays->lock, &delays->blkio_start, total, count); | |
91 | } | |
92 | ||
93 | int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) | |
94 | { | |
95 | u64 utime, stime, stimescaled, utimescaled; | |
96 | unsigned long long t2, t3; | |
97 | unsigned long flags, t1; | |
98 | s64 tmp; | |
99 | ||
100 | task_cputime(tsk, &utime, &stime); | |
101 | tmp = (s64)d->cpu_run_real_total; | |
102 | tmp += utime + stime; | |
103 | d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; | |
104 | ||
105 | task_cputime_scaled(tsk, &utimescaled, &stimescaled); | |
106 | tmp = (s64)d->cpu_scaled_run_real_total; | |
107 | tmp += utimescaled + stimescaled; | |
108 | d->cpu_scaled_run_real_total = | |
109 | (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; | |
110 | ||
111 | /* | |
112 | * No locking available for sched_info (and too expensive to add one) | |
113 | * Mitigate by taking snapshot of values | |
114 | */ | |
115 | t1 = tsk->sched_info.pcount; | |
116 | t2 = tsk->sched_info.run_delay; | |
117 | t3 = tsk->se.sum_exec_runtime; | |
118 | ||
119 | d->cpu_count += t1; | |
120 | ||
121 | tmp = (s64)d->cpu_delay_total + t2; | |
122 | d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; | |
123 | ||
124 | tmp = (s64)d->cpu_run_virtual_total + t3; | |
125 | d->cpu_run_virtual_total = | |
126 | (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; | |
127 | ||
128 | /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ | |
129 | ||
130 | spin_lock_irqsave(&tsk->delays->lock, flags); | |
131 | tmp = d->blkio_delay_total + tsk->delays->blkio_delay; | |
132 | d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; | |
133 | tmp = d->swapin_delay_total + tsk->delays->swapin_delay; | |
134 | d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; | |
135 | tmp = d->freepages_delay_total + tsk->delays->freepages_delay; | |
136 | d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; | |
137 | d->blkio_count += tsk->delays->blkio_count; | |
138 | d->swapin_count += tsk->delays->swapin_count; | |
139 | d->freepages_count += tsk->delays->freepages_count; | |
140 | spin_unlock_irqrestore(&tsk->delays->lock, flags); | |
141 | ||
142 | return 0; | |
143 | } | |
144 | ||
145 | __u64 __delayacct_blkio_ticks(struct task_struct *tsk) | |
146 | { | |
147 | __u64 ret; | |
148 | unsigned long flags; | |
149 | ||
150 | spin_lock_irqsave(&tsk->delays->lock, flags); | |
151 | ret = nsec_to_clock_t(tsk->delays->blkio_delay + | |
152 | tsk->delays->swapin_delay); | |
153 | spin_unlock_irqrestore(&tsk->delays->lock, flags); | |
154 | return ret; | |
155 | } | |
156 | ||
157 | void __delayacct_freepages_start(void) | |
158 | { | |
159 | current->delays->freepages_start = ktime_get_ns(); | |
160 | } | |
161 | ||
162 | void __delayacct_freepages_end(void) | |
163 | { | |
164 | delayacct_end( | |
165 | ¤t->delays->lock, | |
166 | ¤t->delays->freepages_start, | |
167 | ¤t->delays->freepages_delay, | |
168 | ¤t->delays->freepages_count); | |
169 | } | |
170 |