1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <getopt.h>
18 #include <stdint.h>
19 #include <unistd.h>
20
21 #include <thread>
22
23 #include "perfetto/base/logging.h"
24 #include "perfetto/base/time.h"
25
26 // Spawns the requested number threads that alternate between busy-waiting and
27 // sleeping.
28
29 namespace perfetto {
30 namespace {
31
BusyWait(long busy_us,long sleep_us)32 __attribute__((noreturn)) void BusyWait(long busy_us, long sleep_us) {
33 while (1) {
34 base::TimeNanos start = base::GetWallTimeNs();
35 while ((base::GetWallTimeNs() - start).count() < busy_us * 1000) {
36 for (int i = 0; i < 10000; i++) {
37 asm volatile("" ::: "memory");
38 }
39 }
40 if (sleep_us > 0)
41 base::SleepMicroseconds(static_cast<unsigned>(sleep_us));
42 else
43 std::this_thread::yield();
44 }
45 }
46
BusyThreadsMain(int argc,char ** argv)47 int BusyThreadsMain(int argc, char** argv) {
48 long num_threads = -1;
49 long period_us = -1;
50 long duty_cycle = -1;
51
52 static struct option long_options[] = {
53 {"threads", required_argument, nullptr, 't'},
54 {"period_us", required_argument, nullptr, 'p'},
55 {"duty_cycle", required_argument, nullptr, 'd'},
56 {nullptr, 0, nullptr, 0}};
57 int option_index;
58 int c;
59 while ((c = getopt_long(argc, argv, "", long_options, &option_index)) != -1) {
60 switch (c) {
61 case 't':
62 num_threads = atol(optarg);
63 break;
64 case 'p':
65 period_us = atol(optarg);
66 break;
67 case 'd':
68 duty_cycle = atol(optarg);
69 break;
70 default:
71 break;
72 }
73 }
74 if (num_threads < 1 || period_us < 0 || duty_cycle < 1 || duty_cycle > 100) {
75 PERFETTO_ELOG("Usage: %s --threads=N --period_us=N --duty_cycle=[1-100]",
76 argv[0]);
77 return 1;
78 }
79
80 long busy_us = period_us * duty_cycle / 100;
81 long sleep_us = period_us - busy_us;
82
83 PERFETTO_LOG(
84 "Spawning %ld threads; wait duration: %ldus; sleep duration: %ldus.",
85 num_threads, busy_us, sleep_us);
86 for (int i = 0; i < num_threads; i++) {
87 std::thread th(BusyWait, busy_us, sleep_us);
88 th.detach();
89 }
90 PERFETTO_LOG("Threads spawned, Ctrl-C to stop.");
91 while (sleep(600))
92 ;
93
94 return 0;
95 }
96
97 } // namespace
98 } // namespace perfetto
99
main(int argc,char ** argv)100 int main(int argc, char** argv) {
101 return perfetto::BusyThreadsMain(argc, argv);
102 }
103