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/taskstats.h>
19 #include <linux/time.h>
20 #include <linux/sysctl.h>
21 #include <linux/delayacct.h>
22 #include <linux/module.h>
24 int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */
25 EXPORT_SYMBOL_GPL(delayacct_on);
26 struct kmem_cache *delayacct_cache;
28 static int __init delayacct_setup_disable(char *str)
33 __setup("nodelayacct", delayacct_setup_disable);
35 void delayacct_init(void)
37 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC);
38 delayacct_tsk_init(&init_task);
41 void __delayacct_tsk_init(struct task_struct *tsk)
43 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
45 spin_lock_init(&tsk->delays->lock);
49 * Finish delay accounting for a statistic using
50 * its timestamps (@start, @end), accumalator (@total) and @count
53 static void delayacct_end(struct timespec *start, struct timespec *end,
54 u64 *total, u32 *count)
61 ts = timespec_sub(*end, *start);
62 ns = timespec_to_ns(&ts);
66 spin_lock_irqsave(¤t->delays->lock, flags);
69 spin_unlock_irqrestore(¤t->delays->lock, flags);
72 void __delayacct_blkio_start(void)
74 ktime_get_ts(¤t->delays->blkio_start);
77 void __delayacct_blkio_end(void)
79 if (current->delays->flags & DELAYACCT_PF_SWAPIN)
80 /* Swapin block I/O */
81 delayacct_end(¤t->delays->blkio_start,
82 ¤t->delays->blkio_end,
83 ¤t->delays->swapin_delay,
84 ¤t->delays->swapin_count);
85 else /* Other block I/O */
86 delayacct_end(¤t->delays->blkio_start,
87 ¤t->delays->blkio_end,
88 ¤t->delays->blkio_delay,
89 ¤t->delays->blkio_count);
92 int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
96 unsigned long long t2, t3;
99 cputime_t utime, stime, stimescaled, utimescaled;
101 tmp = (s64)d->cpu_run_real_total;
102 task_cputime(tsk, &utime, &stime);
103 cputime_to_timespec(utime + stime, &ts);
104 tmp += timespec_to_ns(&ts);
105 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
107 tmp = (s64)d->cpu_scaled_run_real_total;
108 task_cputime_scaled(tsk, &utimescaled, &stimescaled);
109 cputime_to_timespec(utimescaled + stimescaled, &ts);
110 tmp += timespec_to_ns(&ts);
111 d->cpu_scaled_run_real_total =
112 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
115 * No locking available for sched_info (and too expensive to add one)
116 * Mitigate by taking snapshot of values
118 t1 = tsk->sched_info.pcount;
119 t2 = tsk->sched_info.run_delay;
120 t3 = tsk->se.sum_exec_runtime;
124 tmp = (s64)d->cpu_delay_total + t2;
125 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
127 tmp = (s64)d->cpu_run_virtual_total + t3;
128 d->cpu_run_virtual_total =
129 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
131 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
133 spin_lock_irqsave(&tsk->delays->lock, flags);
134 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
135 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
136 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
137 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
138 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
139 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
140 d->blkio_count += tsk->delays->blkio_count;
141 d->swapin_count += tsk->delays->swapin_count;
142 d->freepages_count += tsk->delays->freepages_count;
143 spin_unlock_irqrestore(&tsk->delays->lock, flags);
148 __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
153 spin_lock_irqsave(&tsk->delays->lock, flags);
154 ret = nsec_to_clock_t(tsk->delays->blkio_delay +
155 tsk->delays->swapin_delay);
156 spin_unlock_irqrestore(&tsk->delays->lock, flags);
160 void __delayacct_freepages_start(void)
162 ktime_get_ts(¤t->delays->freepages_start);
165 void __delayacct_freepages_end(void)
167 delayacct_end(¤t->delays->freepages_start,
168 ¤t->delays->freepages_end,
169 ¤t->delays->freepages_delay,
170 ¤t->delays->freepages_count);