summaryrefslogtreecommitdiffstats
path: root/kernel/delayacct.c
blob: 1be274a462ca0760bfec7e89a8d916e2d866d8c3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
/* delayacct.c - per-task delay accounting
 *
 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
 *
 * This program is free software;  you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/sysctl.h>
#include <linux/delayacct.h>

int delayacct_on __read_mostly;	/* Delay accounting turned on/off */
kmem_cache_t *delayacct_cache;

static int __init delayacct_setup_enable(char *str)
{
	delayacct_on = 1;
	return 1;
}
__setup("delayacct", delayacct_setup_enable);

void delayacct_init(void)
{
	delayacct_cache = kmem_cache_create("delayacct_cache",
					sizeof(struct task_delay_info),
					0,
					SLAB_PANIC,
					NULL, NULL);
	delayacct_tsk_init(&init_task);
}

void __delayacct_tsk_init(struct task_struct *tsk)
{
	spin_lock_init(&tsk->delays_lock);
	/* No need to acquire tsk->delays_lock for allocation here unless
	   __delayacct_tsk_init called after tsk is attached to tasklist
	*/
	tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
	if (tsk->delays)
		spin_lock_init(&tsk->delays->lock);
}

void __delayacct_tsk_exit(struct task_struct *tsk)
{
	struct task_delay_info *delays = tsk->delays;
	spin_lock(&tsk->delays_lock);
	tsk->delays = NULL;
	spin_unlock(&tsk->delays_lock);
	kmem_cache_free(delayacct_cache, delays);
}

/*
 * Start accounting for a delay statistic using
 * its starting timestamp (@start)
 */

static inline void delayacct_start(struct timespec *start)
{
	do_posix_clock_monotonic_gettime(start);
}

/*
 * Finish delay accounting for a statistic using
 * its timestamps (@start, @end), accumalator (@total) and @count
 */

static void delayacct_end(struct timespec *start, struct timespec *end,
				u64 *total, u32 *count)
{
	struct timespec ts;
	s64 ns;

	do_posix_clock_monotonic_gettime(end);
	ts = timespec_sub(*end, *start);
	ns = timespec_to_ns(&ts);
	if (ns < 0)
		return;

	spin_lock(&current->delays->lock);
	*total += ns;
	(*count)++;
	spin_unlock(&current->delays->lock);
}

void __delayacct_blkio_start(void)
{
	delayacct_start(&current->delays->blkio_start);
}

void __delayacct_blkio_end(void)
{
	if (current->delays->flags & DELAYACCT_PF_SWAPIN)
		/* Swapin block I/O */
		delayacct_end(&current->delays->blkio_start,
			&current->delays->blkio_end,
			&current->delays->swapin_delay,
			&current->delays->swapin_count);
	else	/* Other block I/O */
		delayacct_end(&current->delays->blkio_start,
			&current->delays->blkio_end,
			&current->delays->blkio_delay,
			&current->delays->blkio_count);
}

int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
{
	s64 tmp;
	struct timespec ts;
	unsigned long t1,t2,t3;

	spin_lock(&tsk->delays_lock);

	/* Though tsk->delays accessed later, early exit avoids
	 * unnecessary returning of other data
	 */
	if (!tsk->delays)
		goto done;

	tmp = (s64)d->cpu_run_real_total;
	cputime_to_timespec(tsk->utime + tsk->stime, &ts);
	tmp += timespec_to_ns(&ts);
	d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;

	/*
	 * No locking available for sched_info (and too expensive to add one)
	 * Mitigate by taking snapshot of values
	 */
	t1 = tsk->sched_info.pcnt;
	t2 = tsk->sched_info.run_delay;
	t3 = tsk->sched_info.cpu_time;

	d->cpu_count += t1;

	jiffies_to_timespec(t2, &ts);
	tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts);
	d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;

	tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000;
	d->cpu_run_virtual_total =
		(tmp < (s64)d->cpu_run_virtual_total) ?	0 : tmp;

	/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */

	spin_lock(&tsk->delays->lock);
	tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
	d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
	tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
	d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
	d->blkio_count += tsk->delays->blkio_count;
	d->swapin_count += tsk->delays->swapin_count;
	spin_unlock(&tsk->delays->lock);

done:
	spin_unlock(&tsk->delays_lock);
	return 0;
}