lathist_user.c
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
* Copyright (c) 2015 BMW Car IT GmbH
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#define MAX_ENTRIES 20
#define MAX_CPU 4
#define MAX_STARS 40
struct cpu_hist {
long data[MAX_ENTRIES];
long max;
};
static struct cpu_hist cpu_hist[MAX_CPU];
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(void)
{
char starstr[MAX_STARS];
struct cpu_hist *hist;
int i, j;
/* clear screen */
printf("\033[2J");
for (j = 0; j < MAX_CPU; j++) {
hist = &cpu_hist[j];
/* ignore CPUs without data (maybe offline?) */
if (hist->max == 0)
continue;
printf("CPU %d\n", j);
printf(" latency : count distribution\n");
for (i = 1; i <= MAX_ENTRIES; i++) {
stars(starstr, hist->data[i - 1], hist->max, MAX_STARS);
printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
(1l << i) >> 1, (1l << i) - 1,
hist->data[i - 1], MAX_STARS, starstr);
}
}
}
static void get_data(int fd)
{
long key, value;
int c, i;
for (i = 0; i < MAX_CPU; i++)
cpu_hist[i].max = 0;
for (c = 0; c < MAX_CPU; c++) {
for (i = 0; i < MAX_ENTRIES; i++) {
key = c * MAX_ENTRIES + i;
bpf_map_lookup_elem(fd, &key, &value);
cpu_hist[c].data[i] = value;
if (value > cpu_hist[c].max)
cpu_hist[c].max = value;
}
}
}
int main(int argc, char **argv)
{
struct bpf_link *links[2];
struct bpf_program *prog;
struct bpf_object *obj;
char filename[256];
int map_fd, i = 0;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
obj = bpf_object__open_file(filename, NULL);
if (libbpf_get_error(obj)) {
fprintf(stderr, "ERROR: opening BPF object file failed\n");
return 0;
}
/* load BPF program */
if (bpf_object__load(obj)) {
fprintf(stderr, "ERROR: loading BPF object file failed\n");
goto cleanup;
}
map_fd = bpf_object__find_map_fd_by_name(obj, "my_lat");
if (map_fd < 0) {
fprintf(stderr, "ERROR: finding a map in obj file failed\n");
goto cleanup;
}
bpf_object__for_each_program(prog, obj) {
links[i] = bpf_program__attach(prog);
if (libbpf_get_error(links[i])) {
fprintf(stderr, "ERROR: bpf_program__attach failed\n");
links[i] = NULL;
goto cleanup;
}
i++;
}
while (1) {
get_data(map_fd);
print_hist();
sleep(5);
}
cleanup:
for (i--; i >= 0; i--)
bpf_link__destroy(links[i]);
bpf_object__close(obj);
return 0;
}