John Stultz | 51f91cb | 2015-03-11 17:40:02 -0700 | [diff] [blame] | 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 | #ifdef KTEST |
| 29 | #include "../kselftest.h" |
| 30 | #else |
| 31 | static inline int ksft_exit_pass(void) |
| 32 | { |
| 33 | exit(0); |
| 34 | } |
| 35 | static inline int ksft_exit_fail(void) |
| 36 | { |
| 37 | exit(1); |
| 38 | } |
| 39 | #endif |
| 40 | |
| 41 | |
| 42 | #define CLOCK_MONOTONIC_RAW 4 |
| 43 | #define NSEC_PER_SEC 1000000000LL |
| 44 | |
| 45 | #define shift_right(x, s) ({ \ |
| 46 | __typeof__(x) __x = (x); \ |
| 47 | __typeof__(s) __s = (s); \ |
| 48 | __x < 0 ? -(-__x >> __s) : __x >> __s; \ |
| 49 | }) |
| 50 | |
| 51 | long long llabs(long long val) |
| 52 | { |
| 53 | if (val < 0) |
| 54 | val = -val; |
| 55 | return val; |
| 56 | } |
| 57 | |
| 58 | unsigned long long ts_to_nsec(struct timespec ts) |
| 59 | { |
| 60 | return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; |
| 61 | } |
| 62 | |
| 63 | struct timespec nsec_to_ts(long long ns) |
| 64 | { |
| 65 | struct timespec ts; |
| 66 | |
| 67 | ts.tv_sec = ns/NSEC_PER_SEC; |
| 68 | ts.tv_nsec = ns%NSEC_PER_SEC; |
| 69 | return ts; |
| 70 | } |
| 71 | |
| 72 | long long diff_timespec(struct timespec start, struct timespec end) |
| 73 | { |
| 74 | long long start_ns, end_ns; |
| 75 | |
| 76 | start_ns = ts_to_nsec(start); |
| 77 | end_ns = ts_to_nsec(end); |
| 78 | return end_ns - start_ns; |
| 79 | } |
| 80 | |
| 81 | void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw) |
| 82 | { |
| 83 | struct timespec start, mid, end; |
| 84 | long long diff = 0, tmp; |
| 85 | int i; |
| 86 | |
| 87 | for (i = 0; i < 3; i++) { |
| 88 | long long newdiff; |
| 89 | |
| 90 | clock_gettime(CLOCK_MONOTONIC, &start); |
| 91 | clock_gettime(CLOCK_MONOTONIC_RAW, &mid); |
| 92 | clock_gettime(CLOCK_MONOTONIC, &end); |
| 93 | |
| 94 | newdiff = diff_timespec(start, end); |
| 95 | if (diff == 0 || newdiff < diff) { |
| 96 | diff = newdiff; |
| 97 | *raw = mid; |
| 98 | tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2; |
| 99 | *mon = nsec_to_ts(tmp); |
| 100 | } |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | int main(int argv, char **argc) |
| 105 | { |
| 106 | struct timespec mon, raw, start, end; |
| 107 | long long delta1, delta2, interval, eppm, ppm; |
| 108 | struct timex tx1, tx2; |
| 109 | |
| 110 | setbuf(stdout, NULL); |
| 111 | |
| 112 | if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) { |
| 113 | printf("ERR: NO CLOCK_MONOTONIC_RAW\n"); |
| 114 | return -1; |
| 115 | } |
| 116 | |
| 117 | tx1.modes = 0; |
| 118 | adjtimex(&tx1); |
| 119 | get_monotonic_and_raw(&mon, &raw); |
| 120 | start = mon; |
| 121 | delta1 = diff_timespec(mon, raw); |
| 122 | |
| 123 | if (tx1.offset) |
| 124 | printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n"); |
| 125 | |
| 126 | printf("Estimating clock drift: "); |
| 127 | sleep(120); |
| 128 | |
| 129 | get_monotonic_and_raw(&mon, &raw); |
| 130 | end = mon; |
| 131 | tx2.modes = 0; |
| 132 | adjtimex(&tx2); |
| 133 | delta2 = diff_timespec(mon, raw); |
| 134 | |
| 135 | interval = diff_timespec(start, end); |
| 136 | |
| 137 | /* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */ |
| 138 | eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval; |
| 139 | eppm = -eppm; |
| 140 | printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000))); |
| 141 | |
| 142 | /* Avg the two actual freq samples adjtimex gave us */ |
| 143 | ppm = (tx1.freq + tx2.freq) * 1000 / 2; |
| 144 | ppm = (long long)tx1.freq * 1000; |
| 145 | ppm = shift_right(ppm, 16); |
| 146 | printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000))); |
| 147 | |
| 148 | if (llabs(eppm - ppm) > 1000) { |
| 149 | printf(" [FAILED]\n"); |
| 150 | return ksft_exit_fail(); |
| 151 | } |
| 152 | printf(" [OK]\n"); |
| 153 | return ksft_exit_pass(); |
| 154 | } |