148 lines · c
1/* CLOCK_MONOTONIC vs CLOCK_MONOTONIC_RAW skew test2 * by: john stultz (johnstul@us.ibm.com)3 * John Stultz <john.stultz@linaro.org>4 * (C) Copyright IBM 20125 * (C) Copyright Linaro Limited 20156 * Licensed under the GPLv27 *8 * To build:9 * $ gcc raw_skew.c -o raw_skew -lrt10 *11 * This program is free software: you can redistribute it and/or modify12 * it under the terms of the GNU General Public License as published by13 * the Free Software Foundation, either version 2 of the License, or14 * (at your option) any later version.15 *16 * This program is distributed in the hope that it will be useful,17 * but WITHOUT ANY WARRANTY; without even the implied warranty of18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the19 * GNU General Public License for more details.20 */21 22#include <stdio.h>23#include <unistd.h>24#include <stdlib.h>25#include <sys/time.h>26#include <sys/timex.h>27#include <time.h>28#include "../kselftest.h"29 30#define CLOCK_MONOTONIC_RAW 431#define NSEC_PER_SEC 1000000000LL32 33#define shift_right(x, s) ({ \34 __typeof__(x) __x = (x); \35 __typeof__(s) __s = (s); \36 __x < 0 ? -(-__x >> __s) : __x >> __s; \37})38 39long long llabs(long long val)40{41 if (val < 0)42 val = -val;43 return val;44}45 46unsigned long long ts_to_nsec(struct timespec ts)47{48 return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec;49}50 51struct timespec nsec_to_ts(long long ns)52{53 struct timespec ts;54 55 ts.tv_sec = ns/NSEC_PER_SEC;56 ts.tv_nsec = ns%NSEC_PER_SEC;57 return ts;58}59 60long long diff_timespec(struct timespec start, struct timespec end)61{62 long long start_ns, end_ns;63 64 start_ns = ts_to_nsec(start);65 end_ns = ts_to_nsec(end);66 return end_ns - start_ns;67}68 69void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw)70{71 struct timespec start, mid, end;72 long long diff = 0, tmp;73 int i;74 75 for (i = 0; i < 3; i++) {76 long long newdiff;77 78 clock_gettime(CLOCK_MONOTONIC, &start);79 clock_gettime(CLOCK_MONOTONIC_RAW, &mid);80 clock_gettime(CLOCK_MONOTONIC, &end);81 82 newdiff = diff_timespec(start, end);83 if (diff == 0 || newdiff < diff) {84 diff = newdiff;85 *raw = mid;86 tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2;87 *mon = nsec_to_ts(tmp);88 }89 }90}91 92int main(int argc, char **argv)93{94 struct timespec mon, raw, start, end;95 long long delta1, delta2, interval, eppm, ppm;96 struct timex tx1, tx2;97 98 setbuf(stdout, NULL);99 100 if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) {101 printf("ERR: NO CLOCK_MONOTONIC_RAW\n");102 return -1;103 }104 105 tx1.modes = 0;106 adjtimex(&tx1);107 get_monotonic_and_raw(&mon, &raw);108 start = mon;109 delta1 = diff_timespec(mon, raw);110 111 if (tx1.offset)112 printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n");113 114 printf("Estimating clock drift: ");115 fflush(stdout);116 sleep(120);117 118 get_monotonic_and_raw(&mon, &raw);119 end = mon;120 tx2.modes = 0;121 adjtimex(&tx2);122 delta2 = diff_timespec(mon, raw);123 124 interval = diff_timespec(start, end);125 126 /* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */127 eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval;128 eppm = -eppm;129 printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000)));130 131 /* Avg the two actual freq samples adjtimex gave us */132 ppm = (long long)(tx1.freq + tx2.freq) * 1000 / 2;133 ppm = shift_right(ppm, 16);134 printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000)));135 136 if (llabs(eppm - ppm) > 1000) {137 if (tx1.offset || tx2.offset ||138 tx1.freq != tx2.freq || tx1.tick != tx2.tick) {139 printf(" [SKIP]\n");140 ksft_exit_skip("The clock was adjusted externally. Shutdown NTPd or other time sync daemons\n");141 }142 printf(" [FAILED]\n");143 ksft_exit_fail();144 }145 printf(" [OK]\n");146 ksft_exit_pass();147}148