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 | |
39 | long long llabs(long long val) |
40 | { |
41 | if (val < 0) |
42 | val = -val; |
43 | return val; |
44 | } |
45 | |
46 | unsigned long long ts_to_nsec(struct timespec ts) |
47 | { |
48 | return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; |
49 | } |
50 | |
51 | struct 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 | |
60 | long long diff_timespec(struct timespec start, struct timespec end) |
61 | { |
62 | long long start_ns, end_ns; |
63 | |
64 | start_ns = ts_to_nsec(ts: start); |
65 | end_ns = ts_to_nsec(ts: end); |
66 | return end_ns - start_ns; |
67 | } |
68 | |
69 | void 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: start, end: end); |
83 | if (diff == 0 || newdiff < diff) { |
84 | diff = newdiff; |
85 | *raw = mid; |
86 | tmp = (ts_to_nsec(ts: start) + ts_to_nsec(ts: end))/2; |
87 | *mon = nsec_to_ts(tmp); |
88 | } |
89 | } |
90 | } |
91 | |
92 | int main(int argc, char **argv) |
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: &mon, raw: &raw); |
108 | start = mon; |
109 | delta1 = diff_timespec(start: mon, end: 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: &mon, raw: &raw); |
119 | end = mon; |
120 | tx2.modes = 0; |
121 | adjtimex(&tx2); |
122 | delta2 = diff_timespec(start: mon, end: raw); |
123 | |
124 | interval = diff_timespec(start: start, end: 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 = (long long)(tx1.freq + tx2.freq) * 1000 / 2; |
133 | ppm = shift_right(ppm, 16); |
134 | printf(" %lld.%i(act)" , ppm/1000, abs((int)(ppm%1000))); |
135 | |
136 | if (llabs(val: eppm - ppm) > 1000) { |
137 | if (tx1.offset || tx2.offset || |
138 | tx1.freq != tx2.freq || tx1.tick != tx2.tick) { |
139 | printf(" [SKIP]\n" ); |
140 | return ksft_exit_skip(msg: "The clock was adjusted externally. Shutdown NTPd or other time sync daemons\n" ); |
141 | } |
142 | printf(" [FAILED]\n" ); |
143 | return ksft_exit_fail(); |
144 | } |
145 | printf(" [OK]\n" ); |
146 | return ksft_exit_pass(); |
147 | } |
148 | |