1 /* delayacct.c - per-task delay accounting
3 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
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.
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.
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>
22 int delayacct_on __read_mostly; /* Delay accounting turned on/off */
23 kmem_cache_t *delayacct_cache;
25 static int __init delayacct_setup_enable(char *str)
30 __setup("delayacct", delayacct_setup_enable);
32 void delayacct_init(void)
34 delayacct_cache = kmem_cache_create("delayacct_cache",
35 sizeof(struct task_delay_info),
39 delayacct_tsk_init(&init_task);
42 void __delayacct_tsk_init(struct task_struct *tsk)
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
48 tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
50 spin_lock_init(&tsk->delays->lock);
53 void __delayacct_tsk_exit(struct task_struct *tsk)
55 struct task_delay_info *delays = tsk->delays;
56 spin_lock(&tsk->delays_lock);
58 spin_unlock(&tsk->delays_lock);
59 kmem_cache_free(delayacct_cache, delays);
63 * Start accounting for a delay statistic using
64 * its starting timestamp (@start)
67 static inline void delayacct_start(struct timespec *start)
69 do_posix_clock_monotonic_gettime(start);
73 * Finish delay accounting for a statistic using
74 * its timestamps (@start, @end), accumalator (@total) and @count
77 static void delayacct_end(struct timespec *start, struct timespec *end,
78 u64 *total, u32 *count)
83 do_posix_clock_monotonic_gettime(end);
84 ts = timespec_sub(*end, *start);
85 ns = timespec_to_ns(&ts);
89 spin_lock(¤t->delays->lock);
92 spin_unlock(¤t->delays->lock);
95 void __delayacct_blkio_start(void)
97 delayacct_start(¤t->delays->blkio_start);
100 void __delayacct_blkio_end(void)
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);
115 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
119 unsigned long t1,t2,t3;
121 spin_lock(&tsk->delays_lock);
123 /* Though tsk->delays accessed later, early exit avoids
124 * unnecessary returning of other data
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;
135 * No locking available for sched_info (and too expensive to add one)
136 * Mitigate by taking snapshot of values
138 t1 = tsk->sched_info.pcnt;
139 t2 = tsk->sched_info.run_delay;
140 t3 = tsk->sched_info.cpu_time;
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;
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;
152 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
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);
164 spin_unlock(&tsk->delays_lock);
168 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
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);