tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 <linux/bpf.h>
10#include <bpf/bpf.h>
11#include "bpf_load.h"
12
13#define MAX_ENTRIES 20
14#define MAX_CPU 4
15#define MAX_STARS 40
16
17struct cpu_hist {
18 long data[MAX_ENTRIES];
19 long max;
20};
21
22static struct cpu_hist cpu_hist[MAX_CPU];
23
24static void stars(char *str, long val, long max, int width)
25{
26 int i;
27
28 for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
29 str[i] = '*';
30 if (val > max)
31 str[i - 1] = '+';
32 str[i] = '\0';
33}
34
35static void print_hist(void)
36{
37 char starstr[MAX_STARS];
38 struct cpu_hist *hist;
39 int i, j;
40
41 /* clear screen */
42 printf("\033[2J");
43
44 for (j = 0; j < MAX_CPU; j++) {
45 hist = &cpu_hist[j];
46
47 /* ignore CPUs without data (maybe offline?) */
48 if (hist->max == 0)
49 continue;
50
51 printf("CPU %d\n", j);
52 printf(" latency : count distribution\n");
53 for (i = 1; i <= MAX_ENTRIES; i++) {
54 stars(starstr, hist->data[i - 1], hist->max, MAX_STARS);
55 printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
56 (1l << i) >> 1, (1l << i) - 1,
57 hist->data[i - 1], MAX_STARS, starstr);
58 }
59 }
60}
61
62static void get_data(int fd)
63{
64 long key, value;
65 int c, i;
66
67 for (i = 0; i < MAX_CPU; i++)
68 cpu_hist[i].max = 0;
69
70 for (c = 0; c < MAX_CPU; c++) {
71 for (i = 0; i < MAX_ENTRIES; i++) {
72 key = c * MAX_ENTRIES + i;
73 bpf_map_lookup_elem(fd, &key, &value);
74
75 cpu_hist[c].data[i] = value;
76 if (value > cpu_hist[c].max)
77 cpu_hist[c].max = value;
78 }
79 }
80}
81
82int main(int argc, char **argv)
83{
84 char filename[256];
85
86 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
87
88 if (load_bpf_file(filename)) {
89 printf("%s", bpf_log_buf);
90 return 1;
91 }
92
93 while (1) {
94 get_data(map_fd[1]);
95 print_hist();
96 sleep(5);
97 }
98
99 return 0;
100}