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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/*
* latencytop.c: Latency display infrastructure
*
* (C) Copyright 2008 Intel Corporation
* Author: Arjan van de Ven <arjan@linux.intel.com>
*
* 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; version 2
* of the License.
*/
#include <linux/latencytop.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
#include <linux/spinlock.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
static DEFINE_SPINLOCK(latency_lock);
#define MAXLR 128
static struct latency_record latency_record[MAXLR];
int latencytop_enabled;
void clear_all_latency_tracing(struct task_struct *p)
{
unsigned long flags;
if (!latencytop_enabled)
return;
spin_lock_irqsave(&latency_lock, flags);
memset(&p->latency_record, 0, sizeof(p->latency_record));
p->latency_record_count = 0;
spin_unlock_irqrestore(&latency_lock, flags);
}
static void clear_global_latency_tracing(void)
{
unsigned long flags;
spin_lock_irqsave(&latency_lock, flags);
memset(&latency_record, 0, sizeof(latency_record));
spin_unlock_irqrestore(&latency_lock, flags);
}
static void __sched
account_global_scheduler_latency(struct task_struct *tsk, struct latency_record *lat)
{
int firstnonnull = MAXLR + 1;
int i;
if (!latencytop_enabled)
return;
/* skip kernel threads for now */
if (!tsk->mm)
return;
for (i = 0; i < MAXLR; i++) {
int q;
int same = 1;
/* Nothing stored: */
if (!latency_record[i].backtrace[0]) {
if (firstnonnull > i)
firstnonnull = i;
continue;
}
for (q = 0 ; q < LT_BACKTRACEDEPTH ; q++) {
if (latency_record[i].backtrace[q] !=
lat->backtrace[q])
same = 0;
if (same && lat->backtrace[q] == 0)
break;
if (same && lat->backtrace[q] == ULONG_MAX)
break;
}
if (same) {
latency_record[i].count++;
latency_record[i].time += lat->time;
if (lat->time > latency_record[i].max)
latency_record[i].max = lat->time;
return;
}
}
i = firstnonnull;
if (i >= MAXLR - 1)
return;
/* Allocted a new one: */
memcpy(&latency_record[i], lat, sizeof(struct latency_record));
}
static inline void store_stacktrace(struct task_struct *tsk, struct latency_record *lat)
{
struct stack_trace trace;
memset(&trace, 0, sizeof(trace));
trace.max_entries = LT_BACKTRACEDEPTH;
trace.entries = &lat->backtrace[0];
trace.skip = 0;
save_stack_trace_tsk(tsk, &trace);
}
void __sched
account_scheduler_latency(struct task_struct *tsk, int usecs, int inter)
{
unsigned long flags;
int i, q;
struct latency_record lat;
if (!latencytop_enabled)
return;
/* Long interruptible waits are generally user requested... */
if (inter && usecs > 5000)
return;
memset(&lat, 0, sizeof(lat));
lat.count = 1;
lat.time = usecs;
lat.max = usecs;
store_stacktrace(tsk, &lat);
spin_lock_irqsave(&latency_lock, flags);
account_global_scheduler_latency(tsk, &lat);
/*
* short term hack; if we're > 32 we stop; future we recycle:
*/
tsk->latency_record_count++;
if (tsk->latency_record_count >= LT_SAVECOUNT)
goto out_unlock;
for (i = 0; i < LT_SAVECOUNT ; i++) {
struct latency_record *mylat;
int same = 1;
mylat = &tsk->latency_record[i];
for (q = 0 ; q < LT_BACKTRACEDEPTH ; q++) {
if (mylat->backtrace[q] !=
lat.backtrace[q])
same = 0;
if (same && lat.backtrace[q] == 0)
break;
if (same && lat.backtrace[q] == ULONG_MAX)
break;
}
if (same) {
mylat->count++;
mylat->time += lat.time;
if (lat.time > mylat->max)
mylat->max = lat.time;
goto out_unlock;
}
}
/* Allocated a new one: */
i = tsk->latency_record_count;
memcpy(&tsk->latency_record[i], &lat, sizeof(struct latency_record));
out_unlock:
spin_unlock_irqrestore(&latency_lock, flags);
}
static int lstats_show(struct seq_file *m, void *v)
{
int i;
seq_puts(m, "Latency Top version : v0.1\n");
for (i = 0; i < MAXLR; i++) {
if (latency_record[i].backtrace[0]) {
int q;
seq_printf(m, "%i %li %li ",
latency_record[i].count,
latency_record[i].time,
latency_record[i].max);
for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
char sym[KSYM_NAME_LEN];
char *c;
if (!latency_record[i].backtrace[q])
break;
if (latency_record[i].backtrace[q] == ULONG_MAX)
break;
sprint_symbol(sym, latency_record[i].backtrace[q]);
c = strchr(sym, '+');
if (c)
*c = 0;
seq_printf(m, "%s ", sym);
}
seq_printf(m, "\n");
}
}
return 0;
}
static ssize_t
lstats_write(struct file *file, const char __user *buf, size_t count,
loff_t *offs)
{
clear_global_latency_tracing();
return count;
}
static int lstats_open(struct inode *inode, struct file *filp)
{
return single_open(filp, lstats_show, NULL);
}
static struct file_operations lstats_fops = {
.open = lstats_open,
.read = seq_read,
.write = lstats_write,
.llseek = seq_lseek,
.release = single_release,
};
static int __init init_lstats_procfs(void)
{
struct proc_dir_entry *pe;
pe = create_proc_entry("latency_stats", 0644, NULL);
if (!pe)
return -ENOMEM;
pe->proc_fops = &lstats_fops;
return 0;
}
__initcall(init_lstats_procfs);
|
