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ca74e92b SN |
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 | ||
22 | int delayacct_on __read_mostly; /* Delay accounting turned on/off */ | |
23 | kmem_cache_t *delayacct_cache; | |
24 | ||
25 | static int __init delayacct_setup_enable(char *str) | |
26 | { | |
27 | delayacct_on = 1; | |
28 | return 1; | |
29 | } | |
30 | __setup("delayacct", delayacct_setup_enable); | |
31 | ||
32 | void delayacct_init(void) | |
33 | { | |
34 | delayacct_cache = kmem_cache_create("delayacct_cache", | |
35 | sizeof(struct task_delay_info), | |
36 | 0, | |
37 | SLAB_PANIC, | |
38 | NULL, NULL); | |
39 | delayacct_tsk_init(&init_task); | |
40 | } | |
41 | ||
42 | void __delayacct_tsk_init(struct task_struct *tsk) | |
43 | { | |
6f44993f SN |
44 | spin_lock_init(&tsk->delays_lock); |
45 | /* No need to acquire tsk->delays_lock for allocation here unless | |
46 | __delayacct_tsk_init called after tsk is attached to tasklist | |
47 | */ | |
ca74e92b SN |
48 | tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL); |
49 | if (tsk->delays) | |
50 | spin_lock_init(&tsk->delays->lock); | |
51 | } | |
52 | ||
53 | void __delayacct_tsk_exit(struct task_struct *tsk) | |
54 | { | |
6f44993f SN |
55 | struct task_delay_info *delays = tsk->delays; |
56 | spin_lock(&tsk->delays_lock); | |
ca74e92b | 57 | tsk->delays = NULL; |
6f44993f SN |
58 | spin_unlock(&tsk->delays_lock); |
59 | kmem_cache_free(delayacct_cache, delays); | |
ca74e92b SN |
60 | } |
61 | ||
62 | /* | |
63 | * Start accounting for a delay statistic using | |
64 | * its starting timestamp (@start) | |
65 | */ | |
66 | ||
67 | static inline void delayacct_start(struct timespec *start) | |
68 | { | |
69 | do_posix_clock_monotonic_gettime(start); | |
70 | } | |
71 | ||
72 | /* | |
73 | * Finish delay accounting for a statistic using | |
74 | * its timestamps (@start, @end), accumalator (@total) and @count | |
75 | */ | |
76 | ||
77 | static void delayacct_end(struct timespec *start, struct timespec *end, | |
78 | u64 *total, u32 *count) | |
79 | { | |
80 | struct timespec ts; | |
81 | s64 ns; | |
82 | ||
83 | do_posix_clock_monotonic_gettime(end); | |
84 | ts = timespec_sub(*end, *start); | |
85 | ns = timespec_to_ns(&ts); | |
86 | if (ns < 0) | |
87 | return; | |
88 | ||
89 | spin_lock(¤t->delays->lock); | |
90 | *total += ns; | |
91 | (*count)++; | |
92 | spin_unlock(¤t->delays->lock); | |
93 | } | |
94 | ||
0ff92245 SN |
95 | void __delayacct_blkio_start(void) |
96 | { | |
97 | delayacct_start(¤t->delays->blkio_start); | |
98 | } | |
99 | ||
100 | void __delayacct_blkio_end(void) | |
101 | { | |
102 | if (current->delays->flags & DELAYACCT_PF_SWAPIN) | |
103 | /* Swapin block I/O */ | |
104 | delayacct_end(¤t->delays->blkio_start, | |
105 | ¤t->delays->blkio_end, | |
106 | ¤t->delays->swapin_delay, | |
107 | ¤t->delays->swapin_count); | |
108 | else /* Other block I/O */ | |
109 | delayacct_end(¤t->delays->blkio_start, | |
110 | ¤t->delays->blkio_end, | |
111 | ¤t->delays->blkio_delay, | |
112 | ¤t->delays->blkio_count); | |
113 | } | |
6f44993f SN |
114 | |
115 | int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) | |
116 | { | |
117 | s64 tmp; | |
118 | struct timespec ts; | |
119 | unsigned long t1,t2,t3; | |
120 | ||
121 | spin_lock(&tsk->delays_lock); | |
122 | ||
123 | /* Though tsk->delays accessed later, early exit avoids | |
124 | * unnecessary returning of other data | |
125 | */ | |
126 | if (!tsk->delays) | |
127 | goto done; | |
128 | ||
129 | tmp = (s64)d->cpu_run_real_total; | |
130 | cputime_to_timespec(tsk->utime + tsk->stime, &ts); | |
131 | tmp += timespec_to_ns(&ts); | |
132 | d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; | |
133 | ||
134 | /* | |
135 | * No locking available for sched_info (and too expensive to add one) | |
136 | * Mitigate by taking snapshot of values | |
137 | */ | |
138 | t1 = tsk->sched_info.pcnt; | |
139 | t2 = tsk->sched_info.run_delay; | |
140 | t3 = tsk->sched_info.cpu_time; | |
141 | ||
142 | d->cpu_count += t1; | |
143 | ||
144 | jiffies_to_timespec(t2, &ts); | |
145 | tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts); | |
146 | d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; | |
147 | ||
148 | tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000; | |
149 | d->cpu_run_virtual_total = | |
150 | (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp; | |
151 | ||
152 | /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ | |
153 | ||
154 | spin_lock(&tsk->delays->lock); | |
155 | tmp = d->blkio_delay_total + tsk->delays->blkio_delay; | |
156 | d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; | |
157 | tmp = d->swapin_delay_total + tsk->delays->swapin_delay; | |
158 | d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; | |
159 | d->blkio_count += tsk->delays->blkio_count; | |
160 | d->swapin_count += tsk->delays->swapin_count; | |
161 | spin_unlock(&tsk->delays->lock); | |
162 | ||
163 | done: | |
164 | spin_unlock(&tsk->delays_lock); | |
165 | return 0; | |
166 | } | |
25890454 SN |
167 | |
168 | __u64 __delayacct_blkio_ticks(struct task_struct *tsk) | |
169 | { | |
170 | __u64 ret; | |
171 | ||
172 | spin_lock(&tsk->delays->lock); | |
173 | ret = nsec_to_clock_t(tsk->delays->blkio_delay + | |
174 | tsk->delays->swapin_delay); | |
175 | spin_unlock(&tsk->delays->lock); | |
176 | return ret; | |
177 | } | |
178 |