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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 | ||
23 | int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */ | |
24 | struct kmem_cache *delayacct_cache; | |
25 | ||
26 | static int __init delayacct_setup_disable(char *str) | |
27 | { | |
28 | delayacct_on = 0; | |
29 | return 1; | |
30 | } | |
31 | __setup("nodelayacct", delayacct_setup_disable); | |
32 | ||
33 | void delayacct_init(void) | |
34 | { | |
35 | delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC); | |
36 | delayacct_tsk_init(&init_task); | |
37 | } | |
38 | ||
39 | void __delayacct_tsk_init(struct task_struct *tsk) | |
40 | { | |
41 | tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); | |
42 | if (tsk->delays) | |
43 | spin_lock_init(&tsk->delays->lock); | |
44 | } | |
45 | ||
46 | /* | |
47 | * Start accounting for a delay statistic using | |
48 | * its starting timestamp (@start) | |
49 | */ | |
50 | ||
51 | static inline void delayacct_start(struct timespec *start) | |
52 | { | |
53 | do_posix_clock_monotonic_gettime(start); | |
54 | } | |
55 | ||
56 | /* | |
57 | * Finish delay accounting for a statistic using | |
58 | * its timestamps (@start, @end), accumalator (@total) and @count | |
59 | */ | |
60 | ||
61 | static void delayacct_end(struct timespec *start, struct timespec *end, | |
62 | u64 *total, u32 *count) | |
63 | { | |
64 | struct timespec ts; | |
65 | s64 ns; | |
66 | unsigned long flags; | |
67 | ||
68 | do_posix_clock_monotonic_gettime(end); | |
69 | ts = timespec_sub(*end, *start); | |
70 | ns = timespec_to_ns(&ts); | |
71 | if (ns < 0) | |
72 | return; | |
73 | ||
74 | spin_lock_irqsave(¤t->delays->lock, flags); | |
75 | *total += ns; | |
76 | (*count)++; | |
77 | spin_unlock_irqrestore(¤t->delays->lock, flags); | |
78 | } | |
79 | ||
80 | void __delayacct_blkio_start(void) | |
81 | { | |
82 | delayacct_start(¤t->delays->blkio_start); | |
83 | } | |
84 | ||
85 | void __delayacct_blkio_end(void) | |
86 | { | |
87 | if (current->delays->flags & DELAYACCT_PF_SWAPIN) | |
88 | /* Swapin block I/O */ | |
89 | delayacct_end(¤t->delays->blkio_start, | |
90 | ¤t->delays->blkio_end, | |
91 | ¤t->delays->swapin_delay, | |
92 | ¤t->delays->swapin_count); | |
93 | else /* Other block I/O */ | |
94 | delayacct_end(¤t->delays->blkio_start, | |
95 | ¤t->delays->blkio_end, | |
96 | ¤t->delays->blkio_delay, | |
97 | ¤t->delays->blkio_count); | |
98 | } | |
99 | ||
100 | int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) | |
101 | { | |
102 | s64 tmp; | |
103 | unsigned long t1; | |
104 | unsigned long long t2, t3; | |
105 | unsigned long flags; | |
106 | struct timespec ts; | |
107 | ||
108 | /* Though tsk->delays accessed later, early exit avoids | |
109 | * unnecessary returning of other data | |
110 | */ | |
111 | if (!tsk->delays) | |
112 | goto done; | |
113 | ||
114 | tmp = (s64)d->cpu_run_real_total; | |
115 | cputime_to_timespec(tsk->utime + tsk->stime, &ts); | |
116 | tmp += timespec_to_ns(&ts); | |
117 | d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; | |
118 | ||
119 | tmp = (s64)d->cpu_scaled_run_real_total; | |
120 | cputime_to_timespec(tsk->utimescaled + tsk->stimescaled, &ts); | |
121 | tmp += timespec_to_ns(&ts); | |
122 | d->cpu_scaled_run_real_total = | |
123 | (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; | |
124 | ||
125 | /* | |
126 | * No locking available for sched_info (and too expensive to add one) | |
127 | * Mitigate by taking snapshot of values | |
128 | */ | |
129 | t1 = tsk->sched_info.pcount; | |
130 | t2 = tsk->sched_info.run_delay; | |
131 | t3 = tsk->se.sum_exec_runtime; | |
132 | ||
133 | d->cpu_count += t1; | |
134 | ||
135 | tmp = (s64)d->cpu_delay_total + t2; | |
136 | d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; | |
137 | ||
138 | tmp = (s64)d->cpu_run_virtual_total + t3; | |
139 | d->cpu_run_virtual_total = | |
140 | (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; | |
141 | ||
142 | /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ | |
143 | ||
144 | spin_lock_irqsave(&tsk->delays->lock, flags); | |
145 | tmp = d->blkio_delay_total + tsk->delays->blkio_delay; | |
146 | d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; | |
147 | tmp = d->swapin_delay_total + tsk->delays->swapin_delay; | |
148 | d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; | |
149 | tmp = d->freepages_delay_total + tsk->delays->freepages_delay; | |
150 | d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp; | |
151 | d->blkio_count += tsk->delays->blkio_count; | |
152 | d->swapin_count += tsk->delays->swapin_count; | |
153 | d->freepages_count += tsk->delays->freepages_count; | |
154 | spin_unlock_irqrestore(&tsk->delays->lock, flags); | |
155 | ||
156 | done: | |
157 | return 0; | |
158 | } | |
159 | ||
160 | __u64 __delayacct_blkio_ticks(struct task_struct *tsk) | |
161 | { | |
162 | __u64 ret; | |
163 | unsigned long flags; | |
164 | ||
165 | spin_lock_irqsave(&tsk->delays->lock, flags); | |
166 | ret = nsec_to_clock_t(tsk->delays->blkio_delay + | |
167 | tsk->delays->swapin_delay); | |
168 | spin_unlock_irqrestore(&tsk->delays->lock, flags); | |
169 | return ret; | |
170 | } | |
171 | ||
172 | void __delayacct_freepages_start(void) | |
173 | { | |
174 | delayacct_start(¤t->delays->freepages_start); | |
175 | } | |
176 | ||
177 | void __delayacct_freepages_end(void) | |
178 | { | |
179 | delayacct_end(¤t->delays->freepages_start, | |
180 | ¤t->delays->freepages_end, | |
181 | ¤t->delays->freepages_delay, | |
182 | ¤t->delays->freepages_count); | |
183 | } | |
184 |