1// SPDX-License-Identifier: GPL-2.0-only
  2/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
  3 * Copyright (c) 2015 BMW Car IT GmbH
  4 */
  5#include <stdio.h>
  6#include <unistd.h>
  7#include <stdlib.h>
  8#include <signal.h>
  9#include <bpf/libbpf.h>
 10#include <bpf/bpf.h>
 11
 12#define MAX_ENTRIES	20
 13#define MAX_CPU		4
 14#define MAX_STARS	40
 15
 16struct cpu_hist {
 17	long data[MAX_ENTRIES];
 18	long max;
 19};
 20
 21static struct cpu_hist cpu_hist[MAX_CPU];
 22
 23static void stars(char *str, long val, long max, int width)
 24{
 25	int i;
 26
 27	for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
 28		str[i] = '*';
 29	if (val > max)
 30		str[i - 1] = '+';
 31	str[i] = '\0';
 32}
 33
 34static void print_hist(void)
 35{
 36	char starstr[MAX_STARS];
 37	struct cpu_hist *hist;
 38	int i, j;
 39
 40	/* clear screen */
 41	printf("\033[2J");
 42
 43	for (j = 0; j < MAX_CPU; j++) {
 44		hist = &cpu_hist[j];
 45
 46		/* ignore CPUs without data (maybe offline?) */
 47		if (hist->max == 0)
 48			continue;
 49
 50		printf("CPU %d\n", j);
 51		printf("      latency        : count     distribution\n");
 52		for (i = 1; i <= MAX_ENTRIES; i++) {
 53			stars(starstr, hist->data[i - 1], hist->max, MAX_STARS);
 54			printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
 55				(1l << i) >> 1, (1l << i) - 1,
 56				hist->data[i - 1], MAX_STARS, starstr);
 57		}
 58	}
 59}
 60
 61static void get_data(int fd)
 62{
 63	long key, value;
 64	int c, i;
 65
 66	for (i = 0; i < MAX_CPU; i++)
 67		cpu_hist[i].max = 0;
 68
 69	for (c = 0; c < MAX_CPU; c++) {
 70		for (i = 0; i < MAX_ENTRIES; i++) {
 71			key = c * MAX_ENTRIES + i;
 72			bpf_map_lookup_elem(fd, &key, &value);
 73
 74			cpu_hist[c].data[i] = value;
 75			if (value > cpu_hist[c].max)
 76				cpu_hist[c].max = value;
 77		}
 78	}
 79}
 80
 81int main(int argc, char **argv)
 82{
 83	struct bpf_link *links[2];
 84	struct bpf_program *prog;
 85	struct bpf_object *obj;
 86	char filename[256];
 87	int map_fd, i = 0;
 88
 89	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 90	obj = bpf_object__open_file(filename, NULL);
 91	if (libbpf_get_error(obj)) {
 92		fprintf(stderr, "ERROR: opening BPF object file failed\n");
 93		return 0;
 94	}
 95
 96	/* load BPF program */
 97	if (bpf_object__load(obj)) {
 98		fprintf(stderr, "ERROR: loading BPF object file failed\n");
 99		goto cleanup;
100	}
101
102	map_fd = bpf_object__find_map_fd_by_name(obj, "my_lat");
103	if (map_fd < 0) {
104		fprintf(stderr, "ERROR: finding a map in obj file failed\n");
105		goto cleanup;
106	}
107
108	bpf_object__for_each_program(prog, obj) {
109		links[i] = bpf_program__attach(prog);
110		if (libbpf_get_error(links[i])) {
111			fprintf(stderr, "ERROR: bpf_program__attach failed\n");
112			links[i] = NULL;
113			goto cleanup;
114		}
115		i++;
116	}
117
118	while (1) {
119		get_data(map_fd);
120		print_hist();
121		sleep(5);
122	}
123
124cleanup:
125	for (i--; i >= 0; i--)
126		bpf_link__destroy(links[i]);
127
128	bpf_object__close(obj);
129	return 0;
130}