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 = 1; /* Delay accounting turned on/off */
23 struct kmem_cache *delayacct_cache;
24
delayacct_setup_disable(char * str)25 static int __init delayacct_setup_disable(char *str)
26 {
27 delayacct_on = 0;
28 return 1;
29 }
30 __setup("nodelayacct", delayacct_setup_disable);
31
delayacct_init(void)32 void delayacct_init(void)
33 {
34 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC);
35 delayacct_tsk_init(&init_task);
36 }
37
__delayacct_tsk_init(struct task_struct * tsk)38 void __delayacct_tsk_init(struct task_struct *tsk)
39 {
40 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
41 if (tsk->delays)
42 spin_lock_init(&tsk->delays->lock);
43 }
44
45 /*
46 * Start accounting for a delay statistic using
47 * its starting timestamp (@start)
48 */
49
delayacct_start(struct timespec * start)50 static 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
delayacct_end(struct timespec * start,struct timespec * end,u64 * total,u32 * count)60 static void delayacct_end(struct timespec *start, struct timespec *end,
61 u64 *total, u32 *count)
62 {
63 struct timespec ts;
64 s64 ns;
65 unsigned long flags;
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
73 spin_lock_irqsave(¤t->delays->lock, flags);
74 *total += ns;
75 (*count)++;
76 spin_unlock_irqrestore(¤t->delays->lock, flags);
77 }
78
__delayacct_blkio_start(void)79 void __delayacct_blkio_start(void)
80 {
81 delayacct_start(¤t->delays->blkio_start);
82 }
83
__delayacct_blkio_end(void)84 void __delayacct_blkio_end(void)
85 {
86 if (current->delays->flags & DELAYACCT_PF_SWAPIN)
87 /* Swapin block I/O */
88 delayacct_end(¤t->delays->blkio_start,
89 ¤t->delays->blkio_end,
90 ¤t->delays->swapin_delay,
91 ¤t->delays->swapin_count);
92 else /* Other block I/O */
93 delayacct_end(¤t->delays->blkio_start,
94 ¤t->delays->blkio_end,
95 ¤t->delays->blkio_delay,
96 ¤t->delays->blkio_count);
97 }
98
__delayacct_add_tsk(struct taskstats * d,struct task_struct * tsk)99 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
100 {
101 s64 tmp;
102 unsigned long t1;
103 unsigned long long t2, t3;
104 unsigned long flags;
105 struct timespec ts;
106
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
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
124 /*
125 * No locking available for sched_info (and too expensive to add one)
126 * Mitigate by taking snapshot of values
127 */
128 t1 = tsk->sched_info.pcount;
129 t2 = tsk->sched_info.run_delay;
130 t3 = tsk->se.sum_exec_runtime;
131
132 d->cpu_count += t1;
133
134 tmp = (s64)d->cpu_delay_total + t2;
135 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
136
137 tmp = (s64)d->cpu_run_virtual_total + t3;
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
143 spin_lock_irqsave(&tsk->delays->lock, flags);
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;
148 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
149 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
150 d->blkio_count += tsk->delays->blkio_count;
151 d->swapin_count += tsk->delays->swapin_count;
152 d->freepages_count += tsk->delays->freepages_count;
153 spin_unlock_irqrestore(&tsk->delays->lock, flags);
154
155 done:
156 return 0;
157 }
158
__delayacct_blkio_ticks(struct task_struct * tsk)159 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
160 {
161 __u64 ret;
162 unsigned long flags;
163
164 spin_lock_irqsave(&tsk->delays->lock, flags);
165 ret = nsec_to_clock_t(tsk->delays->blkio_delay +
166 tsk->delays->swapin_delay);
167 spin_unlock_irqrestore(&tsk->delays->lock, flags);
168 return ret;
169 }
170
__delayacct_freepages_start(void)171 void __delayacct_freepages_start(void)
172 {
173 delayacct_start(¤t->delays->freepages_start);
174 }
175
__delayacct_freepages_end(void)176 void __delayacct_freepages_end(void)
177 {
178 delayacct_end(¤t->delays->freepages_start,
179 ¤t->delays->freepages_end,
180 ¤t->delays->freepages_delay,
181 ¤t->delays->freepages_count);
182 }
183
184