projects/linux·blob v4.15 · refs

170 lines · 4.6 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/sched/task.h>
18#include <linux/sched/cputime.h>
19#include <linux/slab.h>
20#include <linux/taskstats.h>
21#include <linux/time.h>
22#include <linux/sysctl.h>
23#include <linux/delayacct.h>
24#include <linux/module.h>
25
26int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */
27EXPORT_SYMBOL_GPL(delayacct_on);
28struct kmem_cache *delayacct_cache;
29
30static int __init delayacct_setup_disable(char *str)
31{
32 delayacct_on = 0;
33 return 1;
34}
35__setup("nodelayacct", delayacct_setup_disable);
36
37void delayacct_init(void)
38{
39 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
40 delayacct_tsk_init(&init_task);
41}
42
43void __delayacct_tsk_init(struct task_struct *tsk)
44{
45 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
46 if (tsk->delays)
47 spin_lock_init(&tsk->delays->lock);
48}
49
50/*
51 * Finish delay accounting for a statistic using its timestamps (@start),
52 * accumalator (@total) and @count
53 */
54static void delayacct_end(spinlock_t *lock, u64 *start, u64 *total, u32 *count)
55{
56 s64 ns = ktime_get_ns() - *start;
57 unsigned long flags;
58
59 if (ns > 0) {
60 spin_lock_irqsave(lock, flags);
61 *total += ns;
62 (*count)++;
63 spin_unlock_irqrestore(lock, flags);
64 }
65}
66
67void __delayacct_blkio_start(void)
68{
69 current->delays->blkio_start = ktime_get_ns();
70}
71
72/*
73 * We cannot rely on the `current` macro, as we haven't yet switched back to
74 * the process being woken.
75 */
76void __delayacct_blkio_end(struct task_struct *p)
77{
78 struct task_delay_info *delays = p->delays;
79 u64 *total;
80 u32 *count;
81
82 if (p->delays->flags & DELAYACCT_PF_SWAPIN) {
83 total = &delays->swapin_delay;
84 count = &delays->swapin_count;
85 } else {
86 total = &delays->blkio_delay;
87 count = &delays->blkio_count;
88 }
89
90 delayacct_end(&delays->lock, &delays->blkio_start, total, count);
91}
92
93int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
94{
95 u64 utime, stime, stimescaled, utimescaled;
96 unsigned long long t2, t3;
97 unsigned long flags, t1;
98 s64 tmp;
99
100 task_cputime(tsk, &utime, &stime);
101 tmp = (s64)d->cpu_run_real_total;
102 tmp += utime + stime;
103 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
104
105 task_cputime_scaled(tsk, &utimescaled, &stimescaled);
106 tmp = (s64)d->cpu_scaled_run_real_total;
107 tmp += utimescaled + stimescaled;
108 d->cpu_scaled_run_real_total =
109 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
110
111 /*
112 * No locking available for sched_info (and too expensive to add one)
113 * Mitigate by taking snapshot of values
114 */
115 t1 = tsk->sched_info.pcount;
116 t2 = tsk->sched_info.run_delay;
117 t3 = tsk->se.sum_exec_runtime;
118
119 d->cpu_count += t1;
120
121 tmp = (s64)d->cpu_delay_total + t2;
122 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
123
124 tmp = (s64)d->cpu_run_virtual_total + t3;
125 d->cpu_run_virtual_total =
126 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
127
128 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
129
130 spin_lock_irqsave(&tsk->delays->lock, flags);
131 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
132 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
133 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
134 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
135 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
136 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
137 d->blkio_count += tsk->delays->blkio_count;
138 d->swapin_count += tsk->delays->swapin_count;
139 d->freepages_count += tsk->delays->freepages_count;
140 spin_unlock_irqrestore(&tsk->delays->lock, flags);
141
142 return 0;
143}
144
145__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
146{
147 __u64 ret;
148 unsigned long flags;
149
150 spin_lock_irqsave(&tsk->delays->lock, flags);
151 ret = nsec_to_clock_t(tsk->delays->blkio_delay +
152 tsk->delays->swapin_delay);
153 spin_unlock_irqrestore(&tsk->delays->lock, flags);
154 return ret;
155}
156
157void __delayacct_freepages_start(void)
158{
159 current->delays->freepages_start = ktime_get_ns();
160}
161
162void __delayacct_freepages_end(void)
163{
164 delayacct_end(
165 &current->delays->lock,
166 &current->delays->freepages_start,
167 &current->delays->freepages_delay,
168 &current->delays->freepages_count);
169}
170