// Copyright 2019 Google LLC // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // http://www.apache.org/licenses/LICENSE-2.0 // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> #include <sys/syscall.h> #include <sys/types.h> #include <time.h> #include <unistd.h> // Short program that calls getpid() a number of times and outputs time // diference from the MONOTONIC clock. int main(int argc, char** argv) { struct timespec start, stop; long result; char buf[80]; if (argc < 2) { printf("Usage:./syscall NUM_TIMES_TO_CALL"); return 1; } if (clock_gettime(CLOCK_MONOTONIC, &start)) return 1; long loops = atoi(argv[1]); for (long i = 0; i < loops; i++) { syscall(SYS_gettimeofday, 0, 0); } if (clock_gettime(CLOCK_MONOTONIC, &stop)) return 1; if ((stop.tv_nsec - start.tv_nsec) < 0) { result = (stop.tv_sec - start.tv_sec - 1) * 1000; result += (stop.tv_nsec - start.tv_nsec + 1000000000) / (1000 * 1000); } else { result = (stop.tv_sec - start.tv_sec) * 1000; result += (stop.tv_nsec - start.tv_nsec) / (1000 * 1000); } printf("Called getpid syscall %d times: %lu ms, %lu ns each.\n", loops, result, result * 1000000 / loops); return 0; }