Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
John Stultz | 625 | 100.00% | 2 | 100.00% |
Total | 625 | 2 |
/* CLOCK_MONOTONIC vs CLOCK_MONOTONIC_RAW skew test * by: john stultz (johnstul@us.ibm.com) * John Stultz <john.stultz@linaro.org> * (C) Copyright IBM 2012 * (C) Copyright Linaro Limited 2015 * Licensed under the GPLv2 * * To build: * $ gcc raw_skew.c -o raw_skew -lrt * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <sys/time.h> #include <sys/timex.h> #include <time.h> #include "../kselftest.h" #define CLOCK_MONOTONIC_RAW 4 #define NSEC_PER_SEC 1000000000LL #define shift_right(x, s) ({ \ __typeof__(x) __x = (x); \ __typeof__(s) __s = (s); \ __x < 0 ? -(-__x >> __s) : __x >> __s; \ }) long long llabs(long long val) { if (val < 0) val = -val; return val; } unsigned long long ts_to_nsec(struct timespec ts) { return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; } struct timespec nsec_to_ts(long long ns) { struct timespec ts; ts.tv_sec = ns/NSEC_PER_SEC; ts.tv_nsec = ns%NSEC_PER_SEC; return ts; } long long diff_timespec(struct timespec start, struct timespec end) { long long start_ns, end_ns; start_ns = ts_to_nsec(start); end_ns = ts_to_nsec(end); return end_ns - start_ns; } void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw) { struct timespec start, mid, end; long long diff = 0, tmp; int i; for (i = 0; i < 3; i++) { long long newdiff; clock_gettime(CLOCK_MONOTONIC, &start); clock_gettime(CLOCK_MONOTONIC_RAW, &mid); clock_gettime(CLOCK_MONOTONIC, &end); newdiff = diff_timespec(start, end); if (diff == 0 || newdiff < diff) { diff = newdiff; *raw = mid; tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2; *mon = nsec_to_ts(tmp); } } } int main(int argv, char **argc) { struct timespec mon, raw, start, end; long long delta1, delta2, interval, eppm, ppm; struct timex tx1, tx2; setbuf(stdout, NULL); if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) { printf("ERR: NO CLOCK_MONOTONIC_RAW\n"); return -1; } tx1.modes = 0; adjtimex(&tx1); get_monotonic_and_raw(&mon, &raw); start = mon; delta1 = diff_timespec(mon, raw); if (tx1.offset) printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n"); printf("Estimating clock drift: "); sleep(120); get_monotonic_and_raw(&mon, &raw); end = mon; tx2.modes = 0; adjtimex(&tx2); delta2 = diff_timespec(mon, raw); interval = diff_timespec(start, end); /* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */ eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval; eppm = -eppm; printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000))); /* Avg the two actual freq samples adjtimex gave us */ ppm = (tx1.freq + tx2.freq) * 1000 / 2; ppm = (long long)tx1.freq * 1000; ppm = shift_right(ppm, 16); printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000))); if (llabs(eppm - ppm) > 1000) { if (tx1.offset || tx2.offset || tx1.freq != tx2.freq || tx1.tick != tx2.tick) { printf(" [SKIP]\n"); return ksft_exit_skip("The clock was adjusted externally. Shutdown NTPd or other time sync daemons\n"); } printf(" [FAILED]\n"); return ksft_exit_fail(); } printf(" [OK]\n"); return ksft_exit_pass(); }
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