projects/linux·blob v4.5 · refs

158 lines · 4.5 KiB

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