1 /* CLOCK_MONOTONIC vs CLOCK_MONOTONIC_RAW skew test 2 * by: john stultz (johnstul@us.ibm.com) 3 * John Stultz <john.stultz@linaro.org> 4 * (C) Copyright IBM 2012 5 * (C) Copyright Linaro Limited 2015 6 * Licensed under the GPLv2 7 * 8 * To build: 9 * $ gcc raw_skew.c -o raw_skew -lrt 10 * 11 * This program is free software: you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License as published by 13 * the Free Software Foundation, either version 2 of the License, or 14 * (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 of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * 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 <include/vdso/time64.h> 29 #include "../kselftest.h" 30 31 #define shift_right(x, s) ({ \ 32 __typeof__(x) __x = (x); \ 33 __typeof__(s) __s = (s); \ 34 __x < 0 ? -(-__x >> __s) : __x >> __s; \ 35 }) 36 37 long long llabs(long long val) 38 { 39 if (val < 0) 40 val = -val; 41 return val; 42 } 43 44 unsigned long long ts_to_nsec(struct timespec ts) 45 { 46 return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; 47 } 48 49 struct timespec nsec_to_ts(long long ns) 50 { 51 struct timespec ts; 52 53 ts.tv_sec = ns/NSEC_PER_SEC; 54 ts.tv_nsec = ns%NSEC_PER_SEC; 55 return ts; 56 } 57 58 long long diff_timespec(struct timespec start, struct timespec end) 59 { 60 long long start_ns, end_ns; 61 62 start_ns = ts_to_nsec(start); 63 end_ns = ts_to_nsec(end); 64 return end_ns - start_ns; 65 } 66 67 void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw) 68 { 69 struct timespec start, mid, end; 70 long long diff = 0, tmp; 71 int i; 72 73 for (i = 0; i < 3; i++) { 74 long long newdiff; 75 76 clock_gettime(CLOCK_MONOTONIC, &start); 77 clock_gettime(CLOCK_MONOTONIC_RAW, &mid); 78 clock_gettime(CLOCK_MONOTONIC, &end); 79 80 newdiff = diff_timespec(start, end); 81 if (diff == 0 || newdiff < diff) { 82 diff = newdiff; 83 *raw = mid; 84 tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2; 85 *mon = nsec_to_ts(tmp); 86 } 87 } 88 } 89 90 int main(int argc, char **argv) 91 { 92 struct timespec mon, raw, start, end; 93 long long delta1, delta2, interval, eppm, ppm; 94 struct timex tx1, tx2; 95 96 setbuf(stdout, NULL); 97 98 if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) { 99 printf("ERR: NO CLOCK_MONOTONIC_RAW\n"); 100 return -1; 101 } 102 103 tx1.modes = 0; 104 adjtimex(&tx1); 105 get_monotonic_and_raw(&mon, &raw); 106 start = mon; 107 delta1 = diff_timespec(mon, raw); 108 109 if (tx1.offset) 110 printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n"); 111 112 printf("Estimating clock drift: "); 113 fflush(stdout); 114 sleep(120); 115 116 get_monotonic_and_raw(&mon, &raw); 117 end = mon; 118 tx2.modes = 0; 119 adjtimex(&tx2); 120 delta2 = diff_timespec(mon, raw); 121 122 interval = diff_timespec(start, end); 123 124 /* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */ 125 eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval; 126 eppm = -eppm; 127 printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000))); 128 129 /* Avg the two actual freq samples adjtimex gave us */ 130 ppm = (long long)(tx1.freq + tx2.freq) * 1000 / 2; 131 ppm = shift_right(ppm, 16); 132 printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000))); 133 134 if (llabs(eppm - ppm) > 1000) { 135 if (tx1.offset || tx2.offset || 136 tx1.freq != tx2.freq || tx1.tick != tx2.tick) { 137 printf(" [SKIP]\n"); 138 ksft_exit_skip("The clock was adjusted externally. Shutdown NTPd or other time sync daemons\n"); 139 } 140 printf(" [FAILED]\n"); 141 ksft_exit_fail(); 142 } 143 printf(" [OK]\n"); 144 ksft_exit_pass(); 145 } 146