1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
|
/* 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 argc, char **argv)
{
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: ");
fflush(stdout);
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 = (long long)(tx1.freq + tx2.freq) * 1000 / 2;
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();
}
|
