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
|
/* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <linux/bpf.h>
#include <errno.h>
#include <assert.h>
#include <sys/syscall.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <time.h>
#include <signal.h>
#include "libbpf.h"
#include "bpf_load.h"
static int pmu_fd;
int page_size;
int page_cnt = 8;
volatile struct perf_event_mmap_page *header;
typedef void (*print_fn)(void *data, int size);
static int perf_event_mmap(int fd)
{
void *base;
int mmap_size;
page_size = getpagesize();
mmap_size = page_size * (page_cnt + 1);
base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (base == MAP_FAILED) {
printf("mmap err\n");
return -1;
}
header = base;
return 0;
}
static int perf_event_poll(int fd)
{
struct pollfd pfd = { .fd = fd, .events = POLLIN };
return poll(&pfd, 1, 1000);
}
struct perf_event_sample {
struct perf_event_header header;
__u32 size;
char data[];
};
void perf_event_read(print_fn fn)
{
__u64 data_tail = header->data_tail;
__u64 data_head = header->data_head;
__u64 buffer_size = page_cnt * page_size;
void *base, *begin, *end;
char buf[256];
asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */
if (data_head == data_tail)
return;
base = ((char *)header) + page_size;
begin = base + data_tail % buffer_size;
end = base + data_head % buffer_size;
while (begin != end) {
struct perf_event_sample *e;
e = begin;
if (begin + e->header.size > base + buffer_size) {
long len = base + buffer_size - begin;
assert(len < e->header.size);
memcpy(buf, begin, len);
memcpy(buf + len, base, e->header.size - len);
e = (void *) buf;
begin = base + e->header.size - len;
} else if (begin + e->header.size == base + buffer_size) {
begin = base;
} else {
begin += e->header.size;
}
if (e->header.type == PERF_RECORD_SAMPLE) {
fn(e->data, e->size);
} else if (e->header.type == PERF_RECORD_LOST) {
struct {
struct perf_event_header header;
__u64 id;
__u64 lost;
} *lost = (void *) e;
printf("lost %lld events\n", lost->lost);
} else {
printf("unknown event type=%d size=%d\n",
e->header.type, e->header.size);
}
}
__sync_synchronize(); /* smp_mb() */
header->data_tail = data_head;
}
static __u64 time_get_ns(void)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
return ts.tv_sec * 1000000000ull + ts.tv_nsec;
}
static __u64 start_time;
#define MAX_CNT 100000ll
static void print_bpf_output(void *data, int size)
{
static __u64 cnt;
struct {
__u64 pid;
__u64 cookie;
} *e = data;
if (e->cookie != 0x12345678) {
printf("BUG pid %llx cookie %llx sized %d\n",
e->pid, e->cookie, size);
kill(0, SIGINT);
}
cnt++;
if (cnt == MAX_CNT) {
printf("recv %lld events per sec\n",
MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
kill(0, SIGINT);
}
}
static void test_bpf_perf_event(void)
{
struct perf_event_attr attr = {
.sample_type = PERF_SAMPLE_RAW,
.type = PERF_TYPE_SOFTWARE,
.config = PERF_COUNT_SW_BPF_OUTPUT,
};
int key = 0;
pmu_fd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
assert(pmu_fd >= 0);
assert(bpf_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0);
ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
}
int main(int argc, char **argv)
{
char filename[256];
FILE *f;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
return 1;
}
test_bpf_perf_event();
if (perf_event_mmap(pmu_fd) < 0)
return 1;
f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
(void) f;
start_time = time_get_ns();
for (;;) {
perf_event_poll(pmu_fd);
perf_event_read(print_bpf_output);
}
return 0;
}
|
