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-rw-r--r--kernel/delayacct.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
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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/time.h>
19#include <linux/sysctl.h>
20#include <linux/delayacct.h>
21
22int delayacct_on __read_mostly; /* Delay accounting turned on/off */
23kmem_cache_t *delayacct_cache;
24
25static int __init delayacct_setup_enable(char *str)
26{
27 delayacct_on = 1;
28 return 1;
29}
30__setup("delayacct", delayacct_setup_enable);
31
32void delayacct_init(void)
33{
34 delayacct_cache = kmem_cache_create("delayacct_cache",
35 sizeof(struct task_delay_info),
36 0,
37 SLAB_PANIC,
38 NULL, NULL);
39 delayacct_tsk_init(&init_task);
40}
41
42void __delayacct_tsk_init(struct task_struct *tsk)
43{
44 tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
45 if (tsk->delays)
46 spin_lock_init(&tsk->delays->lock);
47}
48
49void __delayacct_tsk_exit(struct task_struct *tsk)
50{
51 kmem_cache_free(delayacct_cache, tsk->delays);
52 tsk->delays = NULL;
53}
54
55/*
56 * Start accounting for a delay statistic using
57 * its starting timestamp (@start)
58 */
59
60static inline void delayacct_start(struct timespec *start)
61{
62 do_posix_clock_monotonic_gettime(start);
63}
64
65/*
66 * Finish delay accounting for a statistic using
67 * its timestamps (@start, @end), accumalator (@total) and @count
68 */
69
70static void delayacct_end(struct timespec *start, struct timespec *end,
71 u64 *total, u32 *count)
72{
73 struct timespec ts;
74 s64 ns;
75
76 do_posix_clock_monotonic_gettime(end);
77 ts = timespec_sub(*end, *start);
78 ns = timespec_to_ns(&ts);
79 if (ns < 0)
80 return;
81
82 spin_lock(&current->delays->lock);
83 *total += ns;
84 (*count)++;
85 spin_unlock(&current->delays->lock);
86}
87