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Shailabh Nagarca74e922006-07-14 00:24:36 -07001/* 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
Shailabh Nagar163ecdf2006-07-30 03:03:11 -070022int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */
Christoph Lametere18b8902006-12-06 20:33:20 -080023struct kmem_cache *delayacct_cache;
Shailabh Nagarca74e922006-07-14 00:24:36 -070024
Shailabh Nagar163ecdf2006-07-30 03:03:11 -070025static int __init delayacct_setup_disable(char *str)
Shailabh Nagarca74e922006-07-14 00:24:36 -070026{
Shailabh Nagar163ecdf2006-07-30 03:03:11 -070027 delayacct_on = 0;
Shailabh Nagarca74e922006-07-14 00:24:36 -070028 return 1;
29}
Shailabh Nagar163ecdf2006-07-30 03:03:11 -070030__setup("nodelayacct", delayacct_setup_disable);
Shailabh Nagarca74e922006-07-14 00:24:36 -070031
32void delayacct_init(void)
33{
Christoph Lameter0a31bd52007-05-06 14:49:57 -070034 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC);
Shailabh Nagarca74e922006-07-14 00:24:36 -070035 delayacct_tsk_init(&init_task);
36}
37
38void __delayacct_tsk_init(struct task_struct *tsk)
39{
Christoph Lametere94b1762006-12-06 20:33:17 -080040 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
Shailabh Nagarca74e922006-07-14 00:24:36 -070041 if (tsk->delays)
42 spin_lock_init(&tsk->delays->lock);
43}
44
Shailabh Nagarca74e922006-07-14 00:24:36 -070045/*
46 * Start accounting for a delay statistic using
47 * its starting timestamp (@start)
48 */
49
50static inline void delayacct_start(struct timespec *start)
51{
52 do_posix_clock_monotonic_gettime(start);
53}
54
55/*
56 * Finish delay accounting for a statistic using
57 * its timestamps (@start, @end), accumalator (@total) and @count
58 */
59
60static void delayacct_end(struct timespec *start, struct timespec *end,
61 u64 *total, u32 *count)
62{
63 struct timespec ts;
64 s64 ns;
Peter Zijlstra64efade2006-11-05 23:52:10 -080065 unsigned long flags;
Shailabh Nagarca74e922006-07-14 00:24:36 -070066
67 do_posix_clock_monotonic_gettime(end);
68 ts = timespec_sub(*end, *start);
69 ns = timespec_to_ns(&ts);
70 if (ns < 0)
71 return;
72
Peter Zijlstra64efade2006-11-05 23:52:10 -080073 spin_lock_irqsave(&current->delays->lock, flags);
Shailabh Nagarca74e922006-07-14 00:24:36 -070074 *total += ns;
75 (*count)++;
Peter Zijlstra64efade2006-11-05 23:52:10 -080076 spin_unlock_irqrestore(&current->delays->lock, flags);
Shailabh Nagarca74e922006-07-14 00:24:36 -070077}
78
Shailabh Nagar0ff92242006-07-14 00:24:37 -070079void __delayacct_blkio_start(void)
80{
81 delayacct_start(&current->delays->blkio_start);
82}
83
84void __delayacct_blkio_end(void)
85{
86 if (current->delays->flags & DELAYACCT_PF_SWAPIN)
87 /* Swapin block I/O */
88 delayacct_end(&current->delays->blkio_start,
89 &current->delays->blkio_end,
90 &current->delays->swapin_delay,
91 &current->delays->swapin_count);
92 else /* Other block I/O */
93 delayacct_end(&current->delays->blkio_start,
94 &current->delays->blkio_end,
95 &current->delays->blkio_delay,
96 &current->delays->blkio_count);
97}
Shailabh Nagar6f449932006-07-14 00:24:41 -070098
99int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
100{
101 s64 tmp;
Balbir Singh172ba842007-07-09 18:52:00 +0200102 unsigned long t1;
103 unsigned long long t2, t3;
Peter Zijlstra64efade2006-11-05 23:52:10 -0800104 unsigned long flags;
Balbir Singh172ba842007-07-09 18:52:00 +0200105 struct timespec ts;
Shailabh Nagar6f449932006-07-14 00:24:41 -0700106
Shailabh Nagar6f449932006-07-14 00:24:41 -0700107 /* Though tsk->delays accessed later, early exit avoids
108 * unnecessary returning of other data
109 */
110 if (!tsk->delays)
111 goto done;
112
113 tmp = (s64)d->cpu_run_real_total;
114 cputime_to_timespec(tsk->utime + tsk->stime, &ts);
115 tmp += timespec_to_ns(&ts);
116 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
117
Michael Neulingc66f08b2007-10-18 03:06:34 -0700118 tmp = (s64)d->cpu_scaled_run_real_total;
119 cputime_to_timespec(tsk->utimescaled + tsk->stimescaled, &ts);
120 tmp += timespec_to_ns(&ts);
121 d->cpu_scaled_run_real_total =
122 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
123
Shailabh Nagar6f449932006-07-14 00:24:41 -0700124 /*
125 * No locking available for sched_info (and too expensive to add one)
126 * Mitigate by taking snapshot of values
127 */
Ingo Molnar2d723762007-10-15 17:00:12 +0200128 t1 = tsk->sched_info.pcount;
Shailabh Nagar6f449932006-07-14 00:24:41 -0700129 t2 = tsk->sched_info.run_delay;
130 t3 = tsk->sched_info.cpu_time;
131
132 d->cpu_count += t1;
133
Balbir Singh172ba842007-07-09 18:52:00 +0200134 tmp = (s64)d->cpu_delay_total + t2;
Shailabh Nagar6f449932006-07-14 00:24:41 -0700135 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
136
Balbir Singh172ba842007-07-09 18:52:00 +0200137 tmp = (s64)d->cpu_run_virtual_total + t3;
Shailabh Nagar6f449932006-07-14 00:24:41 -0700138 d->cpu_run_virtual_total =
139 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
140
141 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
142
Peter Zijlstra64efade2006-11-05 23:52:10 -0800143 spin_lock_irqsave(&tsk->delays->lock, flags);
Shailabh Nagar6f449932006-07-14 00:24:41 -0700144 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
145 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
146 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
147 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
148 d->blkio_count += tsk->delays->blkio_count;
149 d->swapin_count += tsk->delays->swapin_count;
Peter Zijlstra64efade2006-11-05 23:52:10 -0800150 spin_unlock_irqrestore(&tsk->delays->lock, flags);
Shailabh Nagar6f449932006-07-14 00:24:41 -0700151
152done:
Shailabh Nagar6f449932006-07-14 00:24:41 -0700153 return 0;
154}
Shailabh Nagar25890452006-07-14 00:24:43 -0700155
156__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
157{
158 __u64 ret;
Peter Zijlstra64efade2006-11-05 23:52:10 -0800159 unsigned long flags;
Shailabh Nagar25890452006-07-14 00:24:43 -0700160
Peter Zijlstra64efade2006-11-05 23:52:10 -0800161 spin_lock_irqsave(&tsk->delays->lock, flags);
Shailabh Nagar25890452006-07-14 00:24:43 -0700162 ret = nsec_to_clock_t(tsk->delays->blkio_delay +
163 tsk->delays->swapin_delay);
Peter Zijlstra64efade2006-11-05 23:52:10 -0800164 spin_unlock_irqrestore(&tsk->delays->lock, flags);
Shailabh Nagar25890452006-07-14 00:24:43 -0700165 return ret;
166}
167