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 | #include "../kselftest.h" |
28 | |
29 | #define NSEC_PER_SEC 1000000000ULL |
30 | |
31 | #define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */ |
32 | |
33 | |
34 | #define CLOCK_REALTIME 0 |
35 | #define CLOCK_MONOTONIC 1 |
36 | #define CLOCK_PROCESS_CPUTIME_ID 2 |
37 | #define CLOCK_THREAD_CPUTIME_ID 3 |
38 | #define CLOCK_MONOTONIC_RAW 4 |
39 | #define CLOCK_REALTIME_COARSE 5 |
40 | #define CLOCK_MONOTONIC_COARSE 6 |
41 | #define CLOCK_BOOTTIME 7 |
42 | #define CLOCK_REALTIME_ALARM 8 |
43 | #define CLOCK_BOOTTIME_ALARM 9 |
44 | #define CLOCK_HWSPECIFIC 10 |
45 | #define CLOCK_TAI 11 |
46 | #define NR_CLOCKIDS 12 |
47 | |
48 | #define UNSUPPORTED 0xf00f |
49 | |
50 | char *clockstring(int clockid) |
51 | { |
52 | switch (clockid) { |
53 | case CLOCK_REALTIME: |
54 | return "CLOCK_REALTIME" ; |
55 | case CLOCK_MONOTONIC: |
56 | return "CLOCK_MONOTONIC" ; |
57 | case CLOCK_PROCESS_CPUTIME_ID: |
58 | return "CLOCK_PROCESS_CPUTIME_ID" ; |
59 | case CLOCK_THREAD_CPUTIME_ID: |
60 | return "CLOCK_THREAD_CPUTIME_ID" ; |
61 | case CLOCK_MONOTONIC_RAW: |
62 | return "CLOCK_MONOTONIC_RAW" ; |
63 | case CLOCK_REALTIME_COARSE: |
64 | return "CLOCK_REALTIME_COARSE" ; |
65 | case CLOCK_MONOTONIC_COARSE: |
66 | return "CLOCK_MONOTONIC_COARSE" ; |
67 | case CLOCK_BOOTTIME: |
68 | return "CLOCK_BOOTTIME" ; |
69 | case CLOCK_REALTIME_ALARM: |
70 | return "CLOCK_REALTIME_ALARM" ; |
71 | case CLOCK_BOOTTIME_ALARM: |
72 | return "CLOCK_BOOTTIME_ALARM" ; |
73 | case CLOCK_TAI: |
74 | return "CLOCK_TAI" ; |
75 | }; |
76 | return "UNKNOWN_CLOCKID" ; |
77 | } |
78 | |
79 | struct timespec timespec_add(struct timespec ts, unsigned long long ns) |
80 | { |
81 | ts.tv_nsec += ns; |
82 | while (ts.tv_nsec >= NSEC_PER_SEC) { |
83 | ts.tv_nsec -= NSEC_PER_SEC; |
84 | ts.tv_sec++; |
85 | } |
86 | return ts; |
87 | } |
88 | |
89 | |
90 | long long timespec_sub(struct timespec a, struct timespec b) |
91 | { |
92 | long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec; |
93 | |
94 | ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec; |
95 | return ret; |
96 | } |
97 | |
98 | int nanosleep_lat_test(int clockid, long long ns) |
99 | { |
100 | struct timespec start, end, target; |
101 | long long latency = 0; |
102 | int i, count; |
103 | |
104 | target.tv_sec = ns/NSEC_PER_SEC; |
105 | target.tv_nsec = ns%NSEC_PER_SEC; |
106 | |
107 | if (clock_gettime(clockid, &start)) |
108 | return UNSUPPORTED; |
109 | if (clock_nanosleep(clockid, 0, &target, NULL)) |
110 | return UNSUPPORTED; |
111 | |
112 | count = 10; |
113 | |
114 | /* First check relative latency */ |
115 | clock_gettime(clockid, &start); |
116 | for (i = 0; i < count; i++) |
117 | clock_nanosleep(clockid, 0, &target, NULL); |
118 | clock_gettime(clockid, &end); |
119 | |
120 | if (((timespec_sub(a: start, b: end)/count)-ns) > UNRESONABLE_LATENCY) { |
121 | ksft_print_msg(msg: "Large rel latency: %lld ns :" , (timespec_sub(a: start, b: end)/count)-ns); |
122 | return -1; |
123 | } |
124 | |
125 | /* Next check absolute latency */ |
126 | for (i = 0; i < count; i++) { |
127 | clock_gettime(clockid, &start); |
128 | target = timespec_add(start, ns); |
129 | clock_nanosleep(clockid, TIMER_ABSTIME, &target, NULL); |
130 | clock_gettime(clockid, &end); |
131 | latency += timespec_sub(a: target, b: end); |
132 | } |
133 | |
134 | if (latency/count > UNRESONABLE_LATENCY) { |
135 | ksft_print_msg(msg: "Large abs latency: %lld ns :" , latency/count); |
136 | return -1; |
137 | } |
138 | |
139 | return 0; |
140 | } |
141 | |
142 | #define SKIPPED_CLOCK_COUNT 3 |
143 | |
144 | int main(int argc, char **argv) |
145 | { |
146 | long long length; |
147 | int clockid, ret; |
148 | |
149 | ksft_print_header(); |
150 | ksft_set_plan(NR_CLOCKIDS - CLOCK_REALTIME - SKIPPED_CLOCK_COUNT); |
151 | |
152 | for (clockid = CLOCK_REALTIME; clockid < NR_CLOCKIDS; clockid++) { |
153 | |
154 | /* Skip cputime clockids since nanosleep won't increment cputime */ |
155 | if (clockid == CLOCK_PROCESS_CPUTIME_ID || |
156 | clockid == CLOCK_THREAD_CPUTIME_ID || |
157 | clockid == CLOCK_HWSPECIFIC) |
158 | continue; |
159 | |
160 | length = 10; |
161 | while (length <= (NSEC_PER_SEC * 10)) { |
162 | ret = nanosleep_lat_test(clockid, ns: length); |
163 | if (ret) |
164 | break; |
165 | length *= 100; |
166 | |
167 | } |
168 | |
169 | if (ret == UNSUPPORTED) { |
170 | ksft_test_result_skip(msg: "%s\n" , clockstring(clockid)); |
171 | } else { |
172 | ksft_test_result(ret >= 0, "%s\n" , |
173 | clockstring(clockid)); |
174 | } |
175 | } |
176 | |
177 | ksft_finished(); |
178 | } |
179 | |