projects/linux·blob v5.17 · refs

231 lines · 5.9 KiB

1// SPDX-License-Identifier: GPL-2.0-or-later
2/* delayacct.c - per-task delay accounting
3 *
4 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
5 */
6
7#include <linux/sched.h>
8#include <linux/sched/task.h>
9#include <linux/sched/cputime.h>
10#include <linux/sched/clock.h>
11#include <linux/slab.h>
12#include <linux/taskstats.h>
13#include <linux/sysctl.h>
14#include <linux/delayacct.h>
15#include <linux/module.h>
16
17DEFINE_STATIC_KEY_FALSE(delayacct_key);
18int delayacct_on __read_mostly; /* Delay accounting turned on/off */
19struct kmem_cache *delayacct_cache;
20
21static void set_delayacct(bool enabled)
22{
23 if (enabled) {
24 static_branch_enable(&delayacct_key);
25 delayacct_on = 1;
26 } else {
27 delayacct_on = 0;
28 static_branch_disable(&delayacct_key);
29 }
30}
31
32static int __init delayacct_setup_enable(char *str)
33{
34 delayacct_on = 1;
35 return 1;
36}
37__setup("delayacct", delayacct_setup_enable);
38
39void delayacct_init(void)
40{
41 delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
42 delayacct_tsk_init(&init_task);
43 set_delayacct(delayacct_on);
44}
45
46#ifdef CONFIG_PROC_SYSCTL
47int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
48 size_t *lenp, loff_t *ppos)
49{
50 int state = delayacct_on;
51 struct ctl_table t;
52 int err;
53
54 if (write && !capable(CAP_SYS_ADMIN))
55 return -EPERM;
56
57 t = *table;
58 t.data = &state;
59 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
60 if (err < 0)
61 return err;
62 if (write)
63 set_delayacct(state);
64 return err;
65}
66#endif
67
68void __delayacct_tsk_init(struct task_struct *tsk)
69{
70 tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
71 if (tsk->delays)
72 raw_spin_lock_init(&tsk->delays->lock);
73}
74
75/*
76 * Finish delay accounting for a statistic using its timestamps (@start),
77 * accumalator (@total) and @count
78 */
79static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count)
80{
81 s64 ns = local_clock() - *start;
82 unsigned long flags;
83
84 if (ns > 0) {
85 raw_spin_lock_irqsave(lock, flags);
86 *total += ns;
87 (*count)++;
88 raw_spin_unlock_irqrestore(lock, flags);
89 }
90}
91
92void __delayacct_blkio_start(void)
93{
94 current->delays->blkio_start = local_clock();
95}
96
97/*
98 * We cannot rely on the `current` macro, as we haven't yet switched back to
99 * the process being woken.
100 */
101void __delayacct_blkio_end(struct task_struct *p)
102{
103 delayacct_end(&p->delays->lock,
104 &p->delays->blkio_start,
105 &p->delays->blkio_delay,
106 &p->delays->blkio_count);
107}
108
109int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
110{
111 u64 utime, stime, stimescaled, utimescaled;
112 unsigned long long t2, t3;
113 unsigned long flags, t1;
114 s64 tmp;
115
116 task_cputime(tsk, &utime, &stime);
117 tmp = (s64)d->cpu_run_real_total;
118 tmp += utime + stime;
119 d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
120
121 task_cputime_scaled(tsk, &utimescaled, &stimescaled);
122 tmp = (s64)d->cpu_scaled_run_real_total;
123 tmp += utimescaled + stimescaled;
124 d->cpu_scaled_run_real_total =
125 (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
126
127 /*
128 * No locking available for sched_info (and too expensive to add one)
129 * Mitigate by taking snapshot of values
130 */
131 t1 = tsk->sched_info.pcount;
132 t2 = tsk->sched_info.run_delay;
133 t3 = tsk->se.sum_exec_runtime;
134
135 d->cpu_count += t1;
136
137 tmp = (s64)d->cpu_delay_total + t2;
138 d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
139
140 tmp = (s64)d->cpu_run_virtual_total + t3;
141 d->cpu_run_virtual_total =
142 (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
143
144 if (!tsk->delays)
145 return 0;
146
147 /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
148
149 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
150 tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
151 d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
152 tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
153 d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
154 tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
155 d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
156 tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
157 d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
158 tmp = d->compact_delay_total + tsk->delays->compact_delay;
159 d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
160 d->blkio_count += tsk->delays->blkio_count;
161 d->swapin_count += tsk->delays->swapin_count;
162 d->freepages_count += tsk->delays->freepages_count;
163 d->thrashing_count += tsk->delays->thrashing_count;
164 d->compact_count += tsk->delays->compact_count;
165 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
166
167 return 0;
168}
169
170__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
171{
172 __u64 ret;
173 unsigned long flags;
174
175 raw_spin_lock_irqsave(&tsk->delays->lock, flags);
176 ret = nsec_to_clock_t(tsk->delays->blkio_delay);
177 raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
178 return ret;
179}
180
181void __delayacct_freepages_start(void)
182{
183 current->delays->freepages_start = local_clock();
184}
185
186void __delayacct_freepages_end(void)
187{
188 delayacct_end(&current->delays->lock,
189 &current->delays->freepages_start,
190 &current->delays->freepages_delay,
191 &current->delays->freepages_count);
192}
193
194void __delayacct_thrashing_start(void)
195{
196 current->delays->thrashing_start = local_clock();
197}
198
199void __delayacct_thrashing_end(void)
200{
201 delayacct_end(&current->delays->lock,
202 &current->delays->thrashing_start,
203 &current->delays->thrashing_delay,
204 &current->delays->thrashing_count);
205}
206
207void __delayacct_swapin_start(void)
208{
209 current->delays->swapin_start = local_clock();
210}
211
212void __delayacct_swapin_end(void)
213{
214 delayacct_end(&current->delays->lock,
215 &current->delays->swapin_start,
216 &current->delays->swapin_delay,
217 &current->delays->swapin_count);
218}
219
220void __delayacct_compact_start(void)
221{
222 current->delays->compact_start = local_clock();
223}
224
225void __delayacct_compact_end(void)
226{
227 delayacct_end(&current->delays->lock,
228 &current->delays->compact_start,
229 &current->delays->compact_delay,
230 &current->delays->compact_count);
231}