--- /dev/null
+/* adjtimex() tick adjustment test
+ * by: John Stultz <john.stultz@linaro.org>
+ * (C) Copyright Linaro Limited 2015
+ * Licensed under the GPLv2
+ *
+ * To build:
+ * $ gcc adjtick.c -o adjtick -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>
+
+#ifdef KTEST
+#include "../kselftest.h"
+#else
+static inline int ksft_exit_pass(void)
+{
+ exit(0);
+}
+static inline int ksft_exit_fail(void)
+{
+ exit(1);
+}
+#endif
+
+#define CLOCK_MONOTONIC_RAW 4
+
+#define NSEC_PER_SEC 1000000000LL
+#define USEC_PER_SEC 1000000
+
+#define MILLION 1000000
+
+long systick;
+
+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;
+
+ clock_gettime(CLOCK_MONOTONIC, mon);
+ clock_gettime(CLOCK_MONOTONIC_RAW, raw);
+
+ /* Try to get a more tightly bound pairing */
+ 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);
+ }
+ }
+}
+
+long long get_ppm_drift(void)
+{
+ struct timespec mon_start, raw_start, mon_end, raw_end;
+ long long delta1, delta2, eppm;
+
+ get_monotonic_and_raw(&mon_start, &raw_start);
+
+ sleep(15);
+
+ get_monotonic_and_raw(&mon_end, &raw_end);
+
+ delta1 = diff_timespec(mon_start, mon_end);
+ delta2 = diff_timespec(raw_start, raw_end);
+
+ eppm = (delta1*MILLION)/delta2 - MILLION;
+
+ return eppm;
+}
+
+int check_tick_adj(long tickval)
+{
+ long long eppm, ppm;
+ struct timex tx1;
+
+ tx1.modes = ADJ_TICK;
+ tx1.modes |= ADJ_OFFSET;
+ tx1.modes |= ADJ_FREQUENCY;
+ tx1.modes |= ADJ_STATUS;
+
+ tx1.status = STA_PLL;
+ tx1.offset = 0;
+ tx1.freq = 0;
+ tx1.tick = tickval;
+
+ adjtimex(&tx1);
+
+ sleep(1);
+
+ ppm = ((long long)tickval * MILLION)/systick - MILLION;
+ printf("Estimating tick (act: %ld usec, %lld ppm): ", tickval, ppm);
+
+ eppm = get_ppm_drift();
+ printf("%lld usec, %lld ppm", systick + (systick * eppm / MILLION), eppm);
+
+ tx1.modes = 0;
+ adjtimex(&tx1);
+
+ if (tx1.offset || tx1.freq || tx1.tick != tickval) {
+ printf(" [ERROR]\n");
+ printf("\tUnexpected adjtimex return values, make sure ntpd is not running.\n");
+ return -1;
+ }
+
+ /*
+ * Here we use 100ppm difference as an error bound.
+ * We likely should see better, but some coarse clocksources
+ * cannot match the HZ tick size accurately, so we have a
+ * internal correction factor that doesn't scale exactly
+ * with the adjustment, resulting in > 10ppm error during
+ * a 10% adjustment. 100ppm also gives us more breathing
+ * room for interruptions during the measurement.
+ */
+ if (llabs(eppm - ppm) > 100) {
+ printf(" [FAILED]\n");
+ return -1;
+ }
+ printf(" [OK]\n");
+
+ return 0;
+}
+
+int main(int argv, char **argc)
+{
+ struct timespec raw;
+ long tick, max, interval, err;
+ struct timex tx1;
+
+ err = 0;
+ setbuf(stdout, NULL);
+
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) {
+ printf("ERR: NO CLOCK_MONOTONIC_RAW\n");
+ return -1;
+ }
+
+ printf("Each iteration takes about 15 seconds\n");
+
+ systick = sysconf(_SC_CLK_TCK);
+ systick = USEC_PER_SEC/sysconf(_SC_CLK_TCK);
+ max = systick/10; /* +/- 10% */
+ interval = max/4; /* in 4 steps each side */
+
+ for (tick = (systick - max); tick < (systick + max); tick += interval) {
+ if (check_tick_adj(tick)) {
+ err = 1;
+ break;
+ }
+ }
+
+ /* Reset things to zero */
+ tx1.modes = ADJ_TICK;
+ tx1.modes |= ADJ_OFFSET;
+ tx1.modes |= ADJ_FREQUENCY;
+
+ tx1.offset = 0;
+ tx1.freq = 0;
+ tx1.tick = systick;
+
+ adjtimex(&tx1);
+
+ if (err)
+ return ksft_exit_fail();
+
+ return ksft_exit_pass();
+}
Code Review / kvmfornfv.git / blobdiff