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
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
/* 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();
}
|
