1 /*
2 * Copyright (C) 2023 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 <time.h>
18 #include <unistd.h>
19 #include <chrono>
20 #include <cstring>
21 #include <iostream>
22 #include <optional>
23 #include <sstream>
24 #include <unordered_map>
25
s2ns(uint64_t s)26 uint64_t s2ns(uint64_t s) {
27 return s * 1000000000ull;
28 }
29
PrintHelpAndExit(const std::string & error_msg="")30 void PrintHelpAndExit(const std::string& error_msg = "") {
31 int exit_error = 0;
32 if (!error_msg.empty()) {
33 std::cout << error_msg << "\n";
34 exit_error = 1;
35 }
36
37 std::cout << "Usage: ClockTime [CLOCK_ID] [--trace]\n"
38 << "CLOCK_ID can be CLOCK_REALTIME or CLOCK_MONOTONIC \n"
39 << "if omitted, it will obtain the processors's time-stamp counter \n"
40 << "on x86 it will use RDTSC, on arm64 it will use MRS CNTCVT. \n"
41 << "With --trace flag, it will get snapshot of the current CPU tick, ClockTime \n"
42 << "and the CPU tick per nanoseconds \n"
43 << "-h, --help Print this help message\n";
44
45 exit(exit_error);
46 }
47
GetTime(int type,uint64_t * ts_ns)48 int GetTime(int type, uint64_t* ts_ns) {
49 struct timespec ts;
50 int res = clock_gettime(type, &ts);
51 if (!res) {
52 *ts_ns = s2ns(ts.tv_sec) + ts.tv_nsec;
53 }
54 return res;
55 }
56
GetCPUTicks()57 uint64_t GetCPUTicks() {
58 #if defined(__x86_64__) || defined(__amd64__)
59 uint32_t hi, lo;
60 asm volatile("rdtsc" : "=a"(lo), "=d"(hi));
61 return ((uint64_t)lo) | (((uint64_t)hi) << 32);
62 #elif defined(__aarch64__)
63 uint64_t vct;
64 asm volatile("mrs %0, cntvct_el0" : "=r"(vct));
65 return vct;
66 #else
67 PrintHelpAndExit("GetCPUTicks() is not supported");
68 return 0;
69 #endif
70 }
71
GetCPUTicksPerNanoSecond()72 double GetCPUTicksPerNanoSecond() {
73 uint64_t t0 = GetCPUTicks();
74 auto start = std::chrono::high_resolution_clock::now();
75 sleep(1);
76 uint64_t t1 = GetCPUTicks();
77 auto end = std::chrono::high_resolution_clock::now();
78 auto duration = std::chrono::duration_cast<std::chrono::nanoseconds>(end - start).count();
79 return static_cast<double>(t1 - t0) / duration;
80 }
81
GetClockId(std::string clock_name)82 clockid_t GetClockId(std::string clock_name) {
83 static std::unordered_map<std::string, clockid_t> clock_map = {
84 std::make_pair("CLOCK_REALTIME", CLOCK_REALTIME),
85 std::make_pair("CLOCK_MONOTONIC", CLOCK_MONOTONIC)};
86 auto it = clock_map.find(clock_name);
87 if (it == clock_map.end()) {
88 PrintHelpAndExit("Wrong CLOCK_ID");
89 }
90 return it->second;
91 }
92
main(int argc,char * argv[])93 int main(int argc, char* argv[]) {
94 if (argc == 1) {
95 std::cout << GetCPUTicks() << "\n";
96 } else if (argc == 2) {
97 if (!(strcmp(argv[1], "-h") && strcmp(argv[1], "--help"))) {
98 PrintHelpAndExit();
99 }
100 uint64_t ts_ns;
101 int res = GetTime(GetClockId(argv[1]), &ts_ns);
102 if (res) {
103 std::stringstream err_msg("GetTime() got error:");
104 err_msg << res;
105 PrintHelpAndExit(err_msg.str());
106 }
107 std::cout << ts_ns << "\n";
108 } else if (argc == 3) {
109 if (strcmp(argv[2], "--trace")) {
110 PrintHelpAndExit("Wrong flag");
111 }
112 uint64_t ts_ns;
113 clockid_t clockid = GetClockId(argv[1]);
114 uint64_t cpu_tick = cpu_tick = GetCPUTicks();
115 int res = GetTime(clockid, &ts_ns);
116 if (res) {
117 std::stringstream err_msg("GetTime() got error:");
118 err_msg << res;
119 PrintHelpAndExit(err_msg.str());
120 }
121
122 std::cout << cpu_tick << "\n";
123 std::cout << ts_ns << "\n";
124 std::cout << GetCPUTicksPerNanoSecond() << "\n";
125 } else {
126 PrintHelpAndExit("Wrong number of arguments");
127 }
128
129 return EXIT_SUCCESS;
130 }
131