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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
selftests/timers: Add clock skew estimation test from timetest suite
This adds my clock skew estimation test from the timetest suite.
It measures the drift between CLOCK_MONOTONIC and CLOCK_MONOTONIC_RAW
and compares it with the current frequency value from adjtimex.
It sometimes can trigger false failures when ntpd isn't in a
steady state, but its a useful too when doing adjtimex testing.
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
authored by
John Stultz
and committed by
Shuah Khan
51f91cbd
c5fffcb2
+156
-1
+2
-1
tools/testing/selftests/timers/Makefile
+2
-1
tools/testing/selftests/timers/Makefile
···
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BUILD_FLAGS = -DKTEST
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CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)
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LDFLAGS += -lrt -lpthread
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-
bins = posix_timers nanosleep inconsistency-check nsleep-lat
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bins = posix_timers nanosleep inconsistency-check nsleep-lat raw_skew
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all: ${bins}
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···
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./nanosleep
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./nsleep-lat
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./inconsistency-check
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./raw_skew
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clean:
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rm -f ${bins}
+154
tools/testing/selftests/timers/raw_skew.c
+154
tools/testing/selftests/timers/raw_skew.c
···
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/* CLOCK_MONOTONIC vs CLOCK_MONOTONIC_RAW skew test
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* by: john stultz (johnstul@us.ibm.com)
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* John Stultz <john.stultz@linaro.org>
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* (C) Copyright IBM 2012
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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 raw_skew.c -o raw_skew -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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#ifdef KTEST
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#include "../kselftest.h"
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#else
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static inline int ksft_exit_pass(void)
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{
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exit(0);
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}
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static inline int ksft_exit_fail(void)
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{
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exit(1);
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}
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#endif
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#define CLOCK_MONOTONIC_RAW 4
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#define NSEC_PER_SEC 1000000000LL
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#define shift_right(x, s) ({ \
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__typeof__(x) __x = (x); \
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__typeof__(s) __s = (s); \
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__x < 0 ? -(-__x >> __s) : __x >> __s; \
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})
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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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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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int main(int argv, char **argc)
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{
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struct timespec mon, raw, start, end;
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long long delta1, delta2, interval, eppm, ppm;
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struct timex tx1, tx2;
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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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tx1.modes = 0;
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adjtimex(&tx1);
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get_monotonic_and_raw(&mon, &raw);
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start = mon;
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delta1 = diff_timespec(mon, raw);
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if (tx1.offset)
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printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n");
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printf("Estimating clock drift: ");
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sleep(120);
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get_monotonic_and_raw(&mon, &raw);
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end = mon;
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tx2.modes = 0;
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adjtimex(&tx2);
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delta2 = diff_timespec(mon, raw);
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interval = diff_timespec(start, end);
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/* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */
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eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval;
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eppm = -eppm;
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printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000)));
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/* Avg the two actual freq samples adjtimex gave us */
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ppm = (tx1.freq + tx2.freq) * 1000 / 2;
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ppm = (long long)tx1.freq * 1000;
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ppm = shift_right(ppm, 16);
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printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000)));
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if (llabs(eppm - ppm) > 1000) {
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printf(" [FAILED]\n");
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return ksft_exit_fail();
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}
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printf(" [OK]\n");
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return ksft_exit_pass();
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}