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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 | ||
22 | int delayacct_on __read_mostly; /* Delay accounting turned on/off */ | |
23 | kmem_cache_t *delayacct_cache; | |
24 | ||
25 | static int __init delayacct_setup_enable(char *str) | |
26 | { | |
27 | delayacct_on = 1; | |
28 | return 1; | |
29 | } | |
30 | __setup("delayacct", delayacct_setup_enable); | |
31 | ||
32 | void 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 | ||
42 | void __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 | ||
49 | void __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 | ||
60 | static 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 | ||
70 | static 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(¤t->delays->lock); | |
83 | *total += ns; | |
84 | (*count)++; | |
85 | spin_unlock(¤t->delays->lock); | |
86 | } | |
87 |