56 lines
1.6 KiB
C
56 lines
1.6 KiB
C
// Copyright 2019 Google LLC
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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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// http://www.apache.org/licenses/LICENSE-2.0
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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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#define _GNU_SOURCE
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <time.h>
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#include <unistd.h>
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// Short program that calls getpid() a number of times and outputs time
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// diference from the MONOTONIC clock.
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int main(int argc, char** argv) {
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struct timespec start, stop;
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long result;
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char buf[80];
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if (argc < 2) {
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printf("Usage:./syscall NUM_TIMES_TO_CALL");
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return 1;
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}
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if (clock_gettime(CLOCK_MONOTONIC, &start)) return 1;
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long loops = atoi(argv[1]);
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for (long i = 0; i < loops; i++) {
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syscall(SYS_gettimeofday, 0, 0);
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}
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if (clock_gettime(CLOCK_MONOTONIC, &stop)) return 1;
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if ((stop.tv_nsec - start.tv_nsec) < 0) {
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result = (stop.tv_sec - start.tv_sec - 1) * 1000;
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result += (stop.tv_nsec - start.tv_nsec + 1000000000) / (1000 * 1000);
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} else {
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result = (stop.tv_sec - start.tv_sec) * 1000;
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result += (stop.tv_nsec - start.tv_nsec) / (1000 * 1000);
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}
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printf("Called getpid syscall %d times: %lu ms, %lu ns each.\n", loops,
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result, result * 1000000 / loops);
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return 0;
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}
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