mirror of https://gitee.com/openkylin/linux.git
211 lines
4.5 KiB
C
211 lines
4.5 KiB
C
/* adjtimex() tick adjustment test
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* by: John Stultz <john.stultz@linaro.org>
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* (C) Copyright Linaro Limited 2015
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* Licensed under the GPLv2
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*
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* To build:
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* $ gcc adjtick.c -o adjtick -lrt
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <sys/time.h>
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#include <sys/timex.h>
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#include <time.h>
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#include "../kselftest.h"
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#define CLOCK_MONOTONIC_RAW 4
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#define NSEC_PER_SEC 1000000000LL
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#define USEC_PER_SEC 1000000
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#define MILLION 1000000
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long systick;
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long long llabs(long long val)
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{
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if (val < 0)
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val = -val;
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return val;
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}
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unsigned long long ts_to_nsec(struct timespec ts)
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{
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return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec;
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}
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struct timespec nsec_to_ts(long long ns)
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{
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struct timespec ts;
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ts.tv_sec = ns/NSEC_PER_SEC;
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ts.tv_nsec = ns%NSEC_PER_SEC;
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return ts;
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}
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long long diff_timespec(struct timespec start, struct timespec end)
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{
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long long start_ns, end_ns;
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start_ns = ts_to_nsec(start);
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end_ns = ts_to_nsec(end);
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return end_ns - start_ns;
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}
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void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw)
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{
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struct timespec start, mid, end;
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long long diff = 0, tmp;
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int i;
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clock_gettime(CLOCK_MONOTONIC, mon);
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clock_gettime(CLOCK_MONOTONIC_RAW, raw);
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/* Try to get a more tightly bound pairing */
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for (i = 0; i < 3; i++) {
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long long newdiff;
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clock_gettime(CLOCK_MONOTONIC, &start);
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clock_gettime(CLOCK_MONOTONIC_RAW, &mid);
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clock_gettime(CLOCK_MONOTONIC, &end);
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newdiff = diff_timespec(start, end);
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if (diff == 0 || newdiff < diff) {
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diff = newdiff;
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*raw = mid;
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tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2;
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*mon = nsec_to_ts(tmp);
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}
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}
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}
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long long get_ppm_drift(void)
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{
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struct timespec mon_start, raw_start, mon_end, raw_end;
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long long delta1, delta2, eppm;
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get_monotonic_and_raw(&mon_start, &raw_start);
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sleep(15);
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get_monotonic_and_raw(&mon_end, &raw_end);
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delta1 = diff_timespec(mon_start, mon_end);
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delta2 = diff_timespec(raw_start, raw_end);
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eppm = (delta1*MILLION)/delta2 - MILLION;
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return eppm;
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}
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int check_tick_adj(long tickval)
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{
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long long eppm, ppm;
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struct timex tx1;
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tx1.modes = ADJ_TICK;
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tx1.modes |= ADJ_OFFSET;
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tx1.modes |= ADJ_FREQUENCY;
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tx1.modes |= ADJ_STATUS;
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tx1.status = STA_PLL;
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tx1.offset = 0;
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tx1.freq = 0;
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tx1.tick = tickval;
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adjtimex(&tx1);
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sleep(1);
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ppm = ((long long)tickval * MILLION)/systick - MILLION;
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printf("Estimating tick (act: %ld usec, %lld ppm): ", tickval, ppm);
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eppm = get_ppm_drift();
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printf("%lld usec, %lld ppm", systick + (systick * eppm / MILLION), eppm);
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tx1.modes = 0;
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adjtimex(&tx1);
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if (tx1.offset || tx1.freq || tx1.tick != tickval) {
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printf(" [ERROR]\n");
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printf("\tUnexpected adjtimex return values, make sure ntpd is not running.\n");
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return -1;
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}
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/*
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* Here we use 100ppm difference as an error bound.
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* We likely should see better, but some coarse clocksources
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* cannot match the HZ tick size accurately, so we have a
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* internal correction factor that doesn't scale exactly
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* with the adjustment, resulting in > 10ppm error during
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* a 10% adjustment. 100ppm also gives us more breathing
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* room for interruptions during the measurement.
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*/
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if (llabs(eppm - ppm) > 100) {
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printf(" [FAILED]\n");
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return -1;
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}
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printf(" [OK]\n");
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return 0;
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}
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int main(int argv, char **argc)
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{
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struct timespec raw;
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long tick, max, interval, err;
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struct timex tx1;
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err = 0;
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setbuf(stdout, NULL);
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if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) {
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printf("ERR: NO CLOCK_MONOTONIC_RAW\n");
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return -1;
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}
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printf("Each iteration takes about 15 seconds\n");
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systick = sysconf(_SC_CLK_TCK);
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systick = USEC_PER_SEC/sysconf(_SC_CLK_TCK);
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max = systick/10; /* +/- 10% */
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interval = max/4; /* in 4 steps each side */
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for (tick = (systick - max); tick < (systick + max); tick += interval) {
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if (check_tick_adj(tick)) {
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err = 1;
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break;
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}
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}
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/* Reset things to zero */
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tx1.modes = ADJ_TICK;
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tx1.modes |= ADJ_OFFSET;
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tx1.modes |= ADJ_FREQUENCY;
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tx1.offset = 0;
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tx1.freq = 0;
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tx1.tick = systick;
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adjtimex(&tx1);
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if (err)
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return ksft_exit_fail();
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return ksft_exit_pass();
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}
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