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c5fffcb2 JS |
1 | /* Measure nanosleep timer latency |
2 | * by: john stultz (john.stultz@linaro.org) | |
3 | * (C) Copyright Linaro 2013 | |
4 | * Licensed under the GPLv2 | |
5 | * | |
6 | * To build: | |
7 | * $ gcc nsleep-lat.c -o nsleep-lat -lrt | |
8 | * | |
9 | * This program is free software: you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License as published by | |
11 | * the Free Software Foundation, either version 2 of the License, or | |
12 | * (at your option) any later version. | |
13 | * | |
14 | * This program is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | * GNU General Public License for more details. | |
18 | */ | |
19 | ||
20 | #include <stdio.h> | |
21 | #include <stdlib.h> | |
22 | #include <time.h> | |
23 | #include <sys/time.h> | |
24 | #include <sys/timex.h> | |
25 | #include <string.h> | |
26 | #include <signal.h> | |
27 | #ifdef KTEST | |
28 | #include "../kselftest.h" | |
29 | #else | |
30 | static inline int ksft_exit_pass(void) | |
31 | { | |
32 | exit(0); | |
33 | } | |
34 | static inline int ksft_exit_fail(void) | |
35 | { | |
36 | exit(1); | |
37 | } | |
38 | #endif | |
39 | ||
40 | #define NSEC_PER_SEC 1000000000ULL | |
41 | ||
42 | #define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */ | |
43 | ||
44 | ||
45 | #define CLOCK_REALTIME 0 | |
46 | #define CLOCK_MONOTONIC 1 | |
47 | #define CLOCK_PROCESS_CPUTIME_ID 2 | |
48 | #define CLOCK_THREAD_CPUTIME_ID 3 | |
49 | #define CLOCK_MONOTONIC_RAW 4 | |
50 | #define CLOCK_REALTIME_COARSE 5 | |
51 | #define CLOCK_MONOTONIC_COARSE 6 | |
52 | #define CLOCK_BOOTTIME 7 | |
53 | #define CLOCK_REALTIME_ALARM 8 | |
54 | #define CLOCK_BOOTTIME_ALARM 9 | |
55 | #define CLOCK_HWSPECIFIC 10 | |
56 | #define CLOCK_TAI 11 | |
57 | #define NR_CLOCKIDS 12 | |
58 | ||
59 | #define UNSUPPORTED 0xf00f | |
60 | ||
61 | char *clockstring(int clockid) | |
62 | { | |
63 | switch (clockid) { | |
64 | case CLOCK_REALTIME: | |
65 | return "CLOCK_REALTIME"; | |
66 | case CLOCK_MONOTONIC: | |
67 | return "CLOCK_MONOTONIC"; | |
68 | case CLOCK_PROCESS_CPUTIME_ID: | |
69 | return "CLOCK_PROCESS_CPUTIME_ID"; | |
70 | case CLOCK_THREAD_CPUTIME_ID: | |
71 | return "CLOCK_THREAD_CPUTIME_ID"; | |
72 | case CLOCK_MONOTONIC_RAW: | |
73 | return "CLOCK_MONOTONIC_RAW"; | |
74 | case CLOCK_REALTIME_COARSE: | |
75 | return "CLOCK_REALTIME_COARSE"; | |
76 | case CLOCK_MONOTONIC_COARSE: | |
77 | return "CLOCK_MONOTONIC_COARSE"; | |
78 | case CLOCK_BOOTTIME: | |
79 | return "CLOCK_BOOTTIME"; | |
80 | case CLOCK_REALTIME_ALARM: | |
81 | return "CLOCK_REALTIME_ALARM"; | |
82 | case CLOCK_BOOTTIME_ALARM: | |
83 | return "CLOCK_BOOTTIME_ALARM"; | |
84 | case CLOCK_TAI: | |
85 | return "CLOCK_TAI"; | |
86 | }; | |
87 | return "UNKNOWN_CLOCKID"; | |
88 | } | |
89 | ||
90 | struct timespec timespec_add(struct timespec ts, unsigned long long ns) | |
91 | { | |
92 | ts.tv_nsec += ns; | |
93 | while (ts.tv_nsec >= NSEC_PER_SEC) { | |
94 | ts.tv_nsec -= NSEC_PER_SEC; | |
95 | ts.tv_sec++; | |
96 | } | |
97 | return ts; | |
98 | } | |
99 | ||
100 | ||
101 | long long timespec_sub(struct timespec a, struct timespec b) | |
102 | { | |
103 | long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec; | |
104 | ||
105 | ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec; | |
106 | return ret; | |
107 | } | |
108 | ||
109 | int nanosleep_lat_test(int clockid, long long ns) | |
110 | { | |
111 | struct timespec start, end, target; | |
112 | long long latency = 0; | |
113 | int i, count; | |
114 | ||
115 | target.tv_sec = ns/NSEC_PER_SEC; | |
116 | target.tv_nsec = ns%NSEC_PER_SEC; | |
117 | ||
118 | if (clock_gettime(clockid, &start)) | |
119 | return UNSUPPORTED; | |
120 | if (clock_nanosleep(clockid, 0, &target, NULL)) | |
121 | return UNSUPPORTED; | |
122 | ||
123 | count = 10; | |
124 | ||
125 | /* First check relative latency */ | |
126 | clock_gettime(clockid, &start); | |
127 | for (i = 0; i < count; i++) | |
128 | clock_nanosleep(clockid, 0, &target, NULL); | |
129 | clock_gettime(clockid, &end); | |
130 | ||
131 | if (((timespec_sub(start, end)/count)-ns) > UNRESONABLE_LATENCY) { | |
132 | printf("Large rel latency: %lld ns :", (timespec_sub(start, end)/count)-ns); | |
133 | return -1; | |
134 | } | |
135 | ||
136 | /* Next check absolute latency */ | |
137 | for (i = 0; i < count; i++) { | |
138 | clock_gettime(clockid, &start); | |
139 | target = timespec_add(start, ns); | |
140 | clock_nanosleep(clockid, TIMER_ABSTIME, &target, NULL); | |
141 | clock_gettime(clockid, &end); | |
142 | latency += timespec_sub(target, end); | |
143 | } | |
144 | ||
145 | if (latency/count > UNRESONABLE_LATENCY) { | |
146 | printf("Large abs latency: %lld ns :", latency/count); | |
147 | return -1; | |
148 | } | |
149 | ||
150 | return 0; | |
151 | } | |
152 | ||
153 | ||
154 | ||
155 | int main(int argc, char **argv) | |
156 | { | |
157 | long long length; | |
158 | int clockid, ret; | |
159 | ||
160 | for (clockid = CLOCK_REALTIME; clockid < NR_CLOCKIDS; clockid++) { | |
161 | ||
162 | /* Skip cputime clockids since nanosleep won't increment cputime */ | |
163 | if (clockid == CLOCK_PROCESS_CPUTIME_ID || | |
164 | clockid == CLOCK_THREAD_CPUTIME_ID || | |
165 | clockid == CLOCK_HWSPECIFIC) | |
166 | continue; | |
167 | ||
168 | printf("nsleep latency %-26s ", clockstring(clockid)); | |
169 | ||
170 | length = 10; | |
171 | while (length <= (NSEC_PER_SEC * 10)) { | |
172 | ret = nanosleep_lat_test(clockid, length); | |
173 | if (ret) | |
174 | break; | |
175 | length *= 100; | |
176 | ||
177 | } | |
178 | ||
179 | if (ret == UNSUPPORTED) { | |
180 | printf("[UNSUPPORTED]\n"); | |
181 | continue; | |
182 | } | |
183 | if (ret < 0) { | |
184 | printf("[FAILED]\n"); | |
185 | return ksft_exit_fail(); | |
186 | } | |
187 | printf("[OK]\n"); | |
188 | } | |
189 | return ksft_exit_pass(); | |
190 | } |