1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2 // Copyright (c) 2019 Facebook
3 #include <argp.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <string.h>
7 #include <time.h>
8 #include <bpf/libbpf.h>
9 #include <bpf/bpf.h>
10 #include "runqslower.h"
11 #include "runqslower.skel.h"
12
13 struct env {
14 pid_t pid;
15 __u64 min_us;
16 bool verbose;
17 } env = {
18 .min_us = 10000,
19 };
20
21 const char *argp_program_version = "runqslower 0.1";
22 const char *argp_program_bug_address = "<bpf@vger.kernel.org>";
23 const char argp_program_doc[] =
24 "runqslower Trace long process scheduling delays.\n"
25 " For Linux, uses eBPF, BPF CO-RE, libbpf, BTF.\n"
26 "\n"
27 "This script traces high scheduling delays between tasks being\n"
28 "ready to run and them running on CPU after that.\n"
29 "\n"
30 "USAGE: runqslower [-p PID] [min_us]\n"
31 "\n"
32 "EXAMPLES:\n"
33 " runqslower # trace run queue latency higher than 10000 us (default)\n"
34 " runqslower 1000 # trace run queue latency higher than 1000 us\n"
35 " runqslower -p 123 # trace pid 123 only\n";
36
37 static const struct argp_option opts[] = {
38 { "pid", 'p', "PID", 0, "Process PID to trace"},
39 { "verbose", 'v', NULL, 0, "Verbose debug output" },
40 {},
41 };
42
43 static error_t parse_arg(int key, char *arg, struct argp_state *state)
44 {
45 static int pos_args;
46 int pid;
47 long long min_us;
48
49 switch (key) {
50 case 'v':
51 env.verbose = true;
52 break;
53 case 'p':
54 errno = 0;
55 pid = strtol(arg, NULL, 10);
56 if (errno || pid <= 0) {
57 fprintf(stderr, "Invalid PID: %s\n", arg);
58 argp_usage(state);
59 }
60 env.pid = pid;
61 break;
62 case ARGP_KEY_ARG:
63 if (pos_args++) {
64 fprintf(stderr,
65 "Unrecognized positional argument: %s\n", arg);
66 argp_usage(state);
67 }
68 errno = 0;
69 min_us = strtoll(arg, NULL, 10);
70 if (errno || min_us <= 0) {
71 fprintf(stderr, "Invalid delay (in us): %s\n", arg);
72 argp_usage(state);
73 }
74 env.min_us = min_us;
75 break;
76 default:
77 return ARGP_ERR_UNKNOWN;
78 }
79 return 0;
80 }
81
82 int libbpf_print_fn(enum libbpf_print_level level,
83 const char *format, va_list args)
84 {
85 if (level == LIBBPF_DEBUG && !env.verbose)
86 return 0;
87 return vfprintf(stderr, format, args);
88 }
89
90 void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)
91 {
92 const struct runq_event *e = data;
93 struct tm *tm;
94 char ts[32];
95 time_t t;
96
97 time(&t);
98 tm = localtime(&t);
99 strftime(ts, sizeof(ts), "%H:%M:%S", tm);
100 printf("%-8s %-16s %-6d %14llu\n", ts, e->task, e->pid, e->delta_us);
101 }
102
103 void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)
104 {
105 printf("Lost %llu events on CPU #%d!\n", lost_cnt, cpu);
106 }
107
108 int main(int argc, char **argv)
109 {
110 static const struct argp argp = {
111 .options = opts,
112 .parser = parse_arg,
113 .doc = argp_program_doc,
114 };
115 struct perf_buffer *pb = NULL;
116 struct runqslower_bpf *obj;
117 int err;
118
119 err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
120 if (err)
121 return err;
122
123 libbpf_set_print(libbpf_print_fn);
124
125 /* Use libbpf 1.0 API mode */
126 libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
127
128 obj = runqslower_bpf__open();
129 if (!obj) {
130 fprintf(stderr, "failed to open and/or load BPF object\n");
131 return 1;
132 }
133
134 /* initialize global data (filtering options) */
135 obj->rodata->targ_pid = env.pid;
136 obj->rodata->min_us = env.min_us;
137
138 err = runqslower_bpf__load(obj);
139 if (err) {
140 fprintf(stderr, "failed to load BPF object: %d\n", err);
141 goto cleanup;
142 }
143
144 err = runqslower_bpf__attach(obj);
145 if (err) {
146 fprintf(stderr, "failed to attach BPF programs\n");
147 goto cleanup;
148 }
149
150 printf("Tracing run queue latency higher than %llu us\n", env.min_us);
151 printf("%-8s %-16s %-6s %14s\n", "TIME", "COMM", "PID", "LAT(us)");
152
153 pb = perf_buffer__new(bpf_map__fd(obj->maps.events), 64,
154 handle_event, handle_lost_events, NULL, NULL);
155 err = libbpf_get_error(pb);
156 if (err) {
157 pb = NULL;
158 fprintf(stderr, "failed to open perf buffer: %d\n", err);
159 goto cleanup;
160 }
161
162 while ((err = perf_buffer__poll(pb, 100)) >= 0)
163 ;
164 printf("Error polling perf buffer: %d\n", err);
165
166 cleanup:
167 perf_buffer__free(pb);
168 runqslower_bpf__destroy(obj);
169
170 return err != 0;
171 }
172
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