1 /* adjtimex() tick adjustment test 2 * by: John Stultz <john.stultz@linaro.org> 3 * (C) Copyright Linaro Limited 2015 4 * Licensed under the GPLv2 5 * 6 * To build: 7 * $ gcc adjtick.c -o adjtick -lrt 8 * 9 * This program is free software: you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation, either version 2 of the License, or 12 * (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 * GNU General Public License for more details. 18 */ 19 #include <stdio.h> 20 #include <unistd.h> 21 #include <stdlib.h> 22 #include <sys/time.h> 23 #include <sys/timex.h> 24 #include <time.h> 25 #include <include/vdso/time64.h> 26 27 #include "../kselftest.h" 28 29 #define MILLION 1000000 30 31 long systick; 32 33 long long llabs(long long val) 34 { 35 if (val < 0) 36 val = -val; 37 return val; 38 } 39 40 unsigned long long ts_to_nsec(struct timespec ts) 41 { 42 return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; 43 } 44 45 struct timespec nsec_to_ts(long long ns) 46 { 47 struct timespec ts; 48 49 ts.tv_sec = ns/NSEC_PER_SEC; 50 ts.tv_nsec = ns%NSEC_PER_SEC; 51 52 return ts; 53 } 54 55 long long diff_timespec(struct timespec start, struct timespec end) 56 { 57 long long start_ns, end_ns; 58 59 start_ns = ts_to_nsec(start); 60 end_ns = ts_to_nsec(end); 61 62 return end_ns - start_ns; 63 } 64 65 void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw) 66 { 67 struct timespec start, mid, end; 68 long long diff = 0, tmp; 69 int i; 70 71 clock_gettime(CLOCK_MONOTONIC, mon); 72 clock_gettime(CLOCK_MONOTONIC_RAW, raw); 73 74 /* Try to get a more tightly bound pairing */ 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 92 long long get_ppm_drift(void) 93 { 94 struct timespec mon_start, raw_start, mon_end, raw_end; 95 long long delta1, delta2, eppm; 96 97 get_monotonic_and_raw(&mon_start, &raw_start); 98 99 sleep(15); 100 101 get_monotonic_and_raw(&mon_end, &raw_end); 102 103 delta1 = diff_timespec(mon_start, mon_end); 104 delta2 = diff_timespec(raw_start, raw_end); 105 106 eppm = (delta1*MILLION)/delta2 - MILLION; 107 108 return eppm; 109 } 110 111 int check_tick_adj(long tickval) 112 { 113 long long eppm, ppm; 114 struct timex tx1; 115 116 tx1.modes = ADJ_TICK; 117 tx1.modes |= ADJ_OFFSET; 118 tx1.modes |= ADJ_FREQUENCY; 119 tx1.modes |= ADJ_STATUS; 120 121 tx1.status = STA_PLL; 122 tx1.offset = 0; 123 tx1.freq = 0; 124 tx1.tick = tickval; 125 126 adjtimex(&tx1); 127 128 sleep(1); 129 130 ppm = ((long long)tickval * MILLION)/systick - MILLION; 131 printf("Estimating tick (act: %ld usec, %lld ppm): ", tickval, ppm); 132 133 eppm = get_ppm_drift(); 134 printf("%lld usec, %lld ppm", systick + (systick * eppm / MILLION), eppm); 135 fflush(stdout); 136 137 tx1.modes = 0; 138 adjtimex(&tx1); 139 140 if (tx1.offset || tx1.freq || tx1.tick != tickval) { 141 printf(" [ERROR]\n"); 142 printf("\tUnexpected adjtimex return values, make sure ntpd is not running.\n"); 143 return -1; 144 } 145 146 /* 147 * Here we use 100ppm difference as an error bound. 148 * We likely should see better, but some coarse clocksources 149 * cannot match the HZ tick size accurately, so we have a 150 * internal correction factor that doesn't scale exactly 151 * with the adjustment, resulting in > 10ppm error during 152 * a 10% adjustment. 100ppm also gives us more breathing 153 * room for interruptions during the measurement. 154 */ 155 if (llabs(eppm - ppm) > 100) { 156 printf(" [FAILED]\n"); 157 return -1; 158 } 159 printf(" [OK]\n"); 160 161 return 0; 162 } 163 164 int main(int argc, char **argv) 165 { 166 struct timespec raw; 167 long tick, max, interval, err; 168 struct timex tx1; 169 170 err = 0; 171 setbuf(stdout, NULL); 172 173 if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) { 174 printf("ERR: NO CLOCK_MONOTONIC_RAW\n"); 175 return -1; 176 } 177 178 printf("Each iteration takes about 15 seconds\n"); 179 180 systick = sysconf(_SC_CLK_TCK); 181 systick = USEC_PER_SEC/sysconf(_SC_CLK_TCK); 182 max = systick/10; /* +/- 10% */ 183 interval = max/4; /* in 4 steps each side */ 184 185 for (tick = (systick - max); tick < (systick + max); tick += interval) { 186 if (check_tick_adj(tick)) { 187 err = 1; 188 break; 189 } 190 } 191 192 /* Reset things to zero */ 193 tx1.modes = ADJ_TICK; 194 tx1.modes |= ADJ_OFFSET; 195 tx1.modes |= ADJ_FREQUENCY; 196 197 tx1.offset = 0; 198 tx1.freq = 0; 199 tx1.tick = systick; 200 201 adjtimex(&tx1); 202 203 if (err) 204 ksft_exit_fail(); 205 206 ksft_exit_pass(); 207 } 208