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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/time.h>
19#include <linux/sysctl.h>
20#include <linux/delayacct.h>
21
163ecdff 22int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */
e18b890b 23struct kmem_cache *delayacct_cache;
ca74e92b 24
163ecdff 25static int __init delayacct_setup_disable(char *str)
ca74e92b 26{
163ecdff 27 delayacct_on = 0;
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28 return 1;
29}
163ecdff 30__setup("nodelayacct", delayacct_setup_disable);
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31
32void delayacct_init(void)
33{
0a31bd5f 34 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC);
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35 delayacct_tsk_init(&init_task);
36}
37
38void __delayacct_tsk_init(struct task_struct *tsk)
39{
e94b1766 40 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
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41 if (tsk->delays)
42 spin_lock_init(&tsk->delays->lock);
43}
44
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45/*
46 * Start accounting for a delay statistic using
47 * its starting timestamp (@start)
48 */
49
50static inline void delayacct_start(struct timespec *start)
51{
52 do_posix_clock_monotonic_gettime(start);
53}
54
55/*
56 * Finish delay accounting for a statistic using
57 * its timestamps (@start, @end), accumalator (@total) and @count
58 */
59
60static void delayacct_end(struct timespec *start, struct timespec *end,
61 u64 *total, u32 *count)
62{
63 struct timespec ts;
64 s64 ns;
64efade1 65 unsigned long flags;
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66
67 do_posix_clock_monotonic_gettime(end);
68 ts = timespec_sub(*end, *start);
69 ns = timespec_to_ns(&ts);
70 if (ns < 0)
71 return;
72
64efade1 73 spin_lock_irqsave(&current->delays->lock, flags);
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74 *total += ns;
75 (*count)++;
64efade1 76 spin_unlock_irqrestore(&current->delays->lock, flags);
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77}
78
0ff92245
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79void __delayacct_blkio_start(void)
80{
81 delayacct_start(&current->delays->blkio_start);
82}
83
84void __delayacct_blkio_end(void)
85{
86 if (current->delays->flags & DELAYACCT_PF_SWAPIN)
87 /* Swapin block I/O */
88 delayacct_end(&current->delays->blkio_start,
89 &current->delays->blkio_end,
90 &current->delays->swapin_delay,
91 &current->delays->swapin_count);
92 else /* Other block I/O */
93 delayacct_end(&current->delays->blkio_start,
94 &current->delays->blkio_end,
95 &current->delays->blkio_delay,
96 &current->delays->blkio_count);
97}
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98
99int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
100{
101 s64 tmp;
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102 unsigned long t1;
103 unsigned long long t2, t3;
64efade1 104 unsigned long flags;
172ba844 105 struct timespec ts;
6f44993f 106
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107 /* Though tsk->delays accessed later, early exit avoids
108 * unnecessary returning of other data
109 */
110 if (!tsk->delays)
111 goto done;
112
113 tmp = (s64)d->cpu_run_real_total;
114 cputime_to_timespec(tsk->utime + tsk->stime, &ts);
115 tmp += timespec_to_ns(&ts);
116 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
117
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118 tmp = (s64)d->cpu_scaled_run_real_total;
119 cputime_to_timespec(tsk->utimescaled + tsk->stimescaled, &ts);
120 tmp += timespec_to_ns(&ts);
121 d->cpu_scaled_run_real_total =
122 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
123
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124 /*
125 * No locking available for sched_info (and too expensive to add one)
126 * Mitigate by taking snapshot of values
127 */
2d72376b 128 t1 = tsk->sched_info.pcount;
6f44993f 129 t2 = tsk->sched_info.run_delay;
9c2c4802 130 t3 = tsk->se.sum_exec_runtime;
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131
132 d->cpu_count += t1;
133
172ba844 134 tmp = (s64)d->cpu_delay_total + t2;
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135 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
136
172ba844 137 tmp = (s64)d->cpu_run_virtual_total + t3;
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138 d->cpu_run_virtual_total =
139 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
140
141 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
142
64efade1 143 spin_lock_irqsave(&tsk->delays->lock, flags);
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144 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
145 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
146 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
147 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
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148 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
149 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
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150 d->blkio_count += tsk->delays->blkio_count;
151 d->swapin_count += tsk->delays->swapin_count;
016ae219 152 d->freepages_count += tsk->delays->freepages_count;
64efade1 153 spin_unlock_irqrestore(&tsk->delays->lock, flags);
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154
155done:
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156 return 0;
157}
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158
159__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
160{
161 __u64 ret;
64efade1 162 unsigned long flags;
25890454 163
64efade1 164 spin_lock_irqsave(&tsk->delays->lock, flags);
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165 ret = nsec_to_clock_t(tsk->delays->blkio_delay +
166 tsk->delays->swapin_delay);
64efade1 167 spin_unlock_irqrestore(&tsk->delays->lock, flags);
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168 return ret;
169}
170
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171void __delayacct_freepages_start(void)
172{
173 delayacct_start(&current->delays->freepages_start);
174}
175
176void __delayacct_freepages_end(void)
177{
178 delayacct_end(&current->delays->freepages_start,
179 &current->delays->freepages_end,
180 &current->delays->freepages_delay,
181 &current->delays->freepages_count);
182}
183