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51f91cbd JS |
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 | #ifdef KTEST | |
29 | #include "../kselftest.h" | |
30 | #else | |
31 | static inline int ksft_exit_pass(void) | |
32 | { | |
33 | exit(0); | |
34 | } | |
35 | static inline int ksft_exit_fail(void) | |
36 | { | |
37 | exit(1); | |
38 | } | |
39 | #endif | |
40 | ||
41 | ||
42 | #define CLOCK_MONOTONIC_RAW 4 | |
43 | #define NSEC_PER_SEC 1000000000LL | |
44 | ||
45 | #define shift_right(x, s) ({ \ | |
46 | __typeof__(x) __x = (x); \ | |
47 | __typeof__(s) __s = (s); \ | |
48 | __x < 0 ? -(-__x >> __s) : __x >> __s; \ | |
49 | }) | |
50 | ||
51 | long long llabs(long long val) | |
52 | { | |
53 | if (val < 0) | |
54 | val = -val; | |
55 | return val; | |
56 | } | |
57 | ||
58 | unsigned long long ts_to_nsec(struct timespec ts) | |
59 | { | |
60 | return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; | |
61 | } | |
62 | ||
63 | struct timespec nsec_to_ts(long long ns) | |
64 | { | |
65 | struct timespec ts; | |
66 | ||
67 | ts.tv_sec = ns/NSEC_PER_SEC; | |
68 | ts.tv_nsec = ns%NSEC_PER_SEC; | |
69 | return ts; | |
70 | } | |
71 | ||
72 | long long diff_timespec(struct timespec start, struct timespec end) | |
73 | { | |
74 | long long start_ns, end_ns; | |
75 | ||
76 | start_ns = ts_to_nsec(start); | |
77 | end_ns = ts_to_nsec(end); | |
78 | return end_ns - start_ns; | |
79 | } | |
80 | ||
81 | void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw) | |
82 | { | |
83 | struct timespec start, mid, end; | |
84 | long long diff = 0, tmp; | |
85 | int i; | |
86 | ||
87 | for (i = 0; i < 3; i++) { | |
88 | long long newdiff; | |
89 | ||
90 | clock_gettime(CLOCK_MONOTONIC, &start); | |
91 | clock_gettime(CLOCK_MONOTONIC_RAW, &mid); | |
92 | clock_gettime(CLOCK_MONOTONIC, &end); | |
93 | ||
94 | newdiff = diff_timespec(start, end); | |
95 | if (diff == 0 || newdiff < diff) { | |
96 | diff = newdiff; | |
97 | *raw = mid; | |
98 | tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2; | |
99 | *mon = nsec_to_ts(tmp); | |
100 | } | |
101 | } | |
102 | } | |
103 | ||
104 | int main(int argv, char **argc) | |
105 | { | |
106 | struct timespec mon, raw, start, end; | |
107 | long long delta1, delta2, interval, eppm, ppm; | |
108 | struct timex tx1, tx2; | |
109 | ||
110 | setbuf(stdout, NULL); | |
111 | ||
112 | if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) { | |
113 | printf("ERR: NO CLOCK_MONOTONIC_RAW\n"); | |
114 | return -1; | |
115 | } | |
116 | ||
117 | tx1.modes = 0; | |
118 | adjtimex(&tx1); | |
119 | get_monotonic_and_raw(&mon, &raw); | |
120 | start = mon; | |
121 | delta1 = diff_timespec(mon, raw); | |
122 | ||
123 | if (tx1.offset) | |
124 | printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n"); | |
125 | ||
126 | printf("Estimating clock drift: "); | |
127 | sleep(120); | |
128 | ||
129 | get_monotonic_and_raw(&mon, &raw); | |
130 | end = mon; | |
131 | tx2.modes = 0; | |
132 | adjtimex(&tx2); | |
133 | delta2 = diff_timespec(mon, raw); | |
134 | ||
135 | interval = diff_timespec(start, end); | |
136 | ||
137 | /* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */ | |
138 | eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval; | |
139 | eppm = -eppm; | |
140 | printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000))); | |
141 | ||
142 | /* Avg the two actual freq samples adjtimex gave us */ | |
143 | ppm = (tx1.freq + tx2.freq) * 1000 / 2; | |
144 | ppm = (long long)tx1.freq * 1000; | |
145 | ppm = shift_right(ppm, 16); | |
146 | printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000))); | |
147 | ||
148 | if (llabs(eppm - ppm) > 1000) { | |
149 | printf(" [FAILED]\n"); | |
150 | return ksft_exit_fail(); | |
151 | } | |
152 | printf(" [OK]\n"); | |
153 | return ksft_exit_pass(); | |
154 | } |