131 lines
4.0 KiB
C++
131 lines
4.0 KiB
C++
/*
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* Copyright (C) 2023 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <time.h>
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#include <unistd.h>
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#include <chrono>
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#include <cstring>
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#include <iostream>
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#include <optional>
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#include <sstream>
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#include <unordered_map>
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uint64_t s2ns(uint64_t s) {
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return s * 1000000000ull;
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}
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void PrintHelpAndExit(const std::string& error_msg = "") {
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int exit_error = 0;
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if (!error_msg.empty()) {
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std::cout << error_msg << "\n";
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exit_error = 1;
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}
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std::cout << "Usage: ClockTime [CLOCK_ID] [--trace]\n"
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<< "CLOCK_ID can be CLOCK_REALTIME or CLOCK_MONOTONIC \n"
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<< "if omitted, it will obtain the processors's time-stamp counter \n"
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<< "on x86 it will use RDTSC, on arm64 it will use MRS CNTCVT. \n"
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<< "With --trace flag, it will get snapshot of the current CPU tick, ClockTime \n"
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<< "and the CPU tick per nanoseconds \n"
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<< "-h, --help Print this help message\n";
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exit(exit_error);
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}
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int GetTime(int type, uint64_t* ts_ns) {
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struct timespec ts;
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int res = clock_gettime(type, &ts);
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if (!res) {
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*ts_ns = s2ns(ts.tv_sec) + ts.tv_nsec;
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}
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return res;
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}
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uint64_t GetCPUTicks() {
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#if defined(__x86_64__) || defined(__amd64__)
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uint32_t hi, lo;
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asm volatile("rdtsc" : "=a"(lo), "=d"(hi));
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return ((uint64_t)lo) | (((uint64_t)hi) << 32);
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#elif defined(__aarch64__)
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uint64_t vct;
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asm volatile("mrs %0, cntvct_el0" : "=r"(vct));
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return vct;
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#else
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PrintHelpAndExit("GetCPUTicks() is not supported");
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return 0;
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#endif
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}
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double GetCPUTicksPerNanoSecond() {
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uint64_t t0 = GetCPUTicks();
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auto start = std::chrono::high_resolution_clock::now();
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sleep(1);
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uint64_t t1 = GetCPUTicks();
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auto end = std::chrono::high_resolution_clock::now();
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auto duration = std::chrono::duration_cast<std::chrono::nanoseconds>(end - start).count();
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return static_cast<double>(t1 - t0) / duration;
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}
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clockid_t GetClockId(std::string clock_name) {
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static std::unordered_map<std::string, clockid_t> clock_map = {
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std::make_pair("CLOCK_REALTIME", CLOCK_REALTIME),
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std::make_pair("CLOCK_MONOTONIC", CLOCK_MONOTONIC)};
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auto it = clock_map.find(clock_name);
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if (it == clock_map.end()) {
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PrintHelpAndExit("Wrong CLOCK_ID");
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}
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return it->second;
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}
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int main(int argc, char* argv[]) {
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if (argc == 1) {
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std::cout << GetCPUTicks() << "\n";
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} else if (argc == 2) {
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if (!(strcmp(argv[1], "-h") && strcmp(argv[1], "--help"))) {
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PrintHelpAndExit();
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}
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uint64_t ts_ns;
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int res = GetTime(GetClockId(argv[1]), &ts_ns);
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if (res) {
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std::stringstream err_msg("GetTime() got error:");
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err_msg << res;
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PrintHelpAndExit(err_msg.str());
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}
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std::cout << ts_ns << "\n";
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} else if (argc == 3) {
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if (strcmp(argv[2], "--trace")) {
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PrintHelpAndExit("Wrong flag");
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}
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uint64_t ts_ns;
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clockid_t clockid = GetClockId(argv[1]);
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uint64_t cpu_tick = cpu_tick = GetCPUTicks();
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int res = GetTime(clockid, &ts_ns);
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if (res) {
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std::stringstream err_msg("GetTime() got error:");
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err_msg << res;
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PrintHelpAndExit(err_msg.str());
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}
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std::cout << cpu_tick << "\n";
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std::cout << ts_ns << "\n";
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std::cout << GetCPUTicksPerNanoSecond() << "\n";
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} else {
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PrintHelpAndExit("Wrong number of arguments");
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}
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return EXIT_SUCCESS;
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}
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