LXR linux/tools/testing/selftests/timers/raw

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