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#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <linux/bpf.h>
#include "libbpf.h"
#include "bpf_load.h"
#define MAX_INDEX 64
#define MAX_STARS 38
static void stars(char *str, long val, long max, int width)
{
int i;
for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
str[i] = '*';
if (val > max)
str[i - 1] = '+';
str[i] = '\0';
}
static void print_hist(int fd)
{
int key;
long value;
long data[MAX_INDEX] = {};
char starstr[MAX_STARS];
int i;
int max_ind = -1;
long max_value = 0;
for (key = 0; key < MAX_INDEX; key++) {
bpf_lookup_elem(fd, &key, &value);
data[key] = value;
if (value && key > max_ind)
max_ind = key;
if (value > max_value)
max_value = value;
}
printf(" syscall write() stats\n");
printf(" byte_size : count distribution\n");
for (i = 1; i <= max_ind + 1; i++) {
stars(starstr, data[i - 1], max_value, MAX_STARS);
printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
(1l << i) >> 1, (1l << i) - 1, data[i - 1],
MAX_STARS, starstr);
}
}
static void int_exit(int sig)
{
print_hist(map_fd[1]);
exit(0);
}
int main(int ac, char **argv)
{
char filename[256];
long key, next_key, value;
FILE *f;
int i;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
signal(SIGINT, int_exit);
/* start 'ping' in the background to have some kfree_skb events */
f = popen("ping -c5 localhost", "r");
(void) f;
/* start 'dd' in the background to have plenty of 'write' syscalls */
f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
(void) f;
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
return 1;
}
for (i = 0; i < 5; i++) {
key = 0;
while (bpf_get_next_key(map_fd[0], &key, &next_key) == 0) {
bpf_lookup_elem(map_fd[0], &next_key, &value);
printf("location 0x%lx count %ld\n", next_key, value);
key = next_key;
}
if (key)
printf("\n");
sleep(1);
}
print_hist(map_fd[1]);
return 0;
}
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