1
2
3
4#include <stdio.h>
5#include <stdlib.h>
6#include <signal.h>
7#include <unistd.h>
8#include <stdbool.h>
9#include <string.h>
10#include <sys/resource.h>
11
12#include <bpf/bpf.h>
13#include <bpf/libbpf.h>
14#include "bpf_util.h"
15
16#define SLOTS 100
17
18static void clear_stats(int fd)
19{
20 unsigned int nr_cpus = bpf_num_possible_cpus();
21 __u64 values[nr_cpus];
22 __u32 key;
23
24 memset(values, 0, sizeof(values));
25 for (key = 0; key < SLOTS; key++)
26 bpf_map_update_elem(fd, &key, values, BPF_ANY);
27}
28
29const char *color[] = {
30 "\033[48;5;255m",
31 "\033[48;5;252m",
32 "\033[48;5;250m",
33 "\033[48;5;248m",
34 "\033[48;5;246m",
35 "\033[48;5;244m",
36 "\033[48;5;242m",
37 "\033[48;5;240m",
38 "\033[48;5;238m",
39 "\033[48;5;236m",
40 "\033[48;5;234m",
41 "\033[48;5;232m",
42};
43const int num_colors = ARRAY_SIZE(color);
44
45const char nocolor[] = "\033[00m";
46
47const char *sym[] = {
48 " ",
49 " ",
50 ".",
51 ".",
52 "*",
53 "*",
54 "o",
55 "o",
56 "O",
57 "O",
58 "#",
59 "#",
60};
61
62bool full_range = false;
63bool text_only = false;
64
65static void print_banner(void)
66{
67 if (full_range)
68 printf("|1ns |10ns |100ns |1us |10us |100us"
69 " |1ms |10ms |100ms |1s |10s\n");
70 else
71 printf("|1us |10us |100us |1ms |10ms "
72 "|100ms |1s |10s\n");
73}
74
75static void print_hist(int fd)
76{
77 unsigned int nr_cpus = bpf_num_possible_cpus();
78 __u64 total_events = 0;
79 long values[nr_cpus];
80 __u64 max_cnt = 0;
81 __u64 cnt[SLOTS];
82 __u64 value;
83 __u32 key;
84 int i;
85
86 for (key = 0; key < SLOTS; key++) {
87 bpf_map_lookup_elem(fd, &key, values);
88 value = 0;
89 for (i = 0; i < nr_cpus; i++)
90 value += values[i];
91 cnt[key] = value;
92 total_events += value;
93 if (value > max_cnt)
94 max_cnt = value;
95 }
96 clear_stats(fd);
97 for (key = full_range ? 0 : 29; key < SLOTS; key++) {
98 int c = num_colors * cnt[key] / (max_cnt + 1);
99
100 if (text_only)
101 printf("%s", sym[c]);
102 else
103 printf("%s %s", color[c], nocolor);
104 }
105 printf(" # %lld\n", total_events);
106}
107
108int main(int ac, char **argv)
109{
110 struct bpf_link *links[2];
111 struct bpf_program *prog;
112 struct bpf_object *obj;
113 char filename[256];
114 int map_fd, i, j = 0;
115
116 for (i = 1; i < ac; i++) {
117 if (strcmp(argv[i], "-a") == 0) {
118 full_range = true;
119 } else if (strcmp(argv[i], "-t") == 0) {
120 text_only = true;
121 } else if (strcmp(argv[i], "-h") == 0) {
122 printf("Usage:\n"
123 " -a display wider latency range\n"
124 " -t text only\n");
125 return 1;
126 }
127 }
128
129 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
130 obj = bpf_object__open_file(filename, NULL);
131 if (libbpf_get_error(obj)) {
132 fprintf(stderr, "ERROR: opening BPF object file failed\n");
133 return 0;
134 }
135
136
137 if (bpf_object__load(obj)) {
138 fprintf(stderr, "ERROR: loading BPF object file failed\n");
139 goto cleanup;
140 }
141
142 map_fd = bpf_object__find_map_fd_by_name(obj, "lat_map");
143 if (map_fd < 0) {
144 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
145 goto cleanup;
146 }
147
148 bpf_object__for_each_program(prog, obj) {
149 links[j] = bpf_program__attach(prog);
150 if (libbpf_get_error(links[j])) {
151 fprintf(stderr, "ERROR: bpf_program__attach failed\n");
152 links[j] = NULL;
153 goto cleanup;
154 }
155 j++;
156 }
157
158 printf(" heatmap of IO latency\n");
159 if (text_only)
160 printf(" %s", sym[num_colors - 1]);
161 else
162 printf(" %s %s", color[num_colors - 1], nocolor);
163 printf(" - many events with this latency\n");
164
165 if (text_only)
166 printf(" %s", sym[0]);
167 else
168 printf(" %s %s", color[0], nocolor);
169 printf(" - few events\n");
170
171 for (i = 0; ; i++) {
172 if (i % 20 == 0)
173 print_banner();
174 print_hist(map_fd);
175 sleep(2);
176 }
177
178cleanup:
179 for (j--; j >= 0; j--)
180 bpf_link__destroy(links[j]);
181
182 bpf_object__close(obj);
183 return 0;
184}
185
