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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 <include/vdso/time64.h>
28#include "../kselftest.h"
29
30#define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */
31
32/* CLOCK_HWSPECIFIC == CLOCK_SGI_CYCLE (Deprecated) */
33#define CLOCK_HWSPECIFIC 10
34
35#define UNSUPPORTED 0xf00f
36
37char *clockstring(int clockid)
38{
39 switch (clockid) {
40 case CLOCK_REALTIME:
41 return "CLOCK_REALTIME";
42 case CLOCK_MONOTONIC:
43 return "CLOCK_MONOTONIC";
44 case CLOCK_PROCESS_CPUTIME_ID:
45 return "CLOCK_PROCESS_CPUTIME_ID";
46 case CLOCK_THREAD_CPUTIME_ID:
47 return "CLOCK_THREAD_CPUTIME_ID";
48 case CLOCK_MONOTONIC_RAW:
49 return "CLOCK_MONOTONIC_RAW";
50 case CLOCK_REALTIME_COARSE:
51 return "CLOCK_REALTIME_COARSE";
52 case CLOCK_MONOTONIC_COARSE:
53 return "CLOCK_MONOTONIC_COARSE";
54 case CLOCK_BOOTTIME:
55 return "CLOCK_BOOTTIME";
56 case CLOCK_REALTIME_ALARM:
57 return "CLOCK_REALTIME_ALARM";
58 case CLOCK_BOOTTIME_ALARM:
59 return "CLOCK_BOOTTIME_ALARM";
60 case CLOCK_TAI:
61 return "CLOCK_TAI";
62 };
63 return "UNKNOWN_CLOCKID";
64}
65
66struct timespec timespec_add(struct timespec ts, unsigned long long ns)
67{
68 ts.tv_nsec += ns;
69 while (ts.tv_nsec >= NSEC_PER_SEC) {
70 ts.tv_nsec -= NSEC_PER_SEC;
71 ts.tv_sec++;
72 }
73 return ts;
74}
75
76
77long long timespec_sub(struct timespec a, struct timespec b)
78{
79 long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;
80
81 ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
82 return ret;
83}
84
85int nanosleep_lat_test(int clockid, long long ns)
86{
87 struct timespec start, end, target;
88 long long latency = 0;
89 int i, count;
90
91 target.tv_sec = ns/NSEC_PER_SEC;
92 target.tv_nsec = ns%NSEC_PER_SEC;
93
94 if (clock_gettime(clockid, &start))
95 return UNSUPPORTED;
96 if (clock_nanosleep(clockid, 0, &target, NULL))
97 return UNSUPPORTED;
98
99 count = 10;
100
101 /* First check relative latency */
102 clock_gettime(clockid, &start);
103 for (i = 0; i < count; i++)
104 clock_nanosleep(clockid, 0, &target, NULL);
105 clock_gettime(clockid, &end);
106
107 if (((timespec_sub(start, end)/count)-ns) > UNRESONABLE_LATENCY) {
108 ksft_print_msg("Large rel latency: %lld ns :", (timespec_sub(start, end)/count)-ns);
109 return -1;
110 }
111
112 /* Next check absolute latency */
113 for (i = 0; i < count; i++) {
114 clock_gettime(clockid, &start);
115 target = timespec_add(start, ns);
116 clock_nanosleep(clockid, TIMER_ABSTIME, &target, NULL);
117 clock_gettime(clockid, &end);
118 latency += timespec_sub(target, end);
119 }
120
121 if (latency/count > UNRESONABLE_LATENCY) {
122 ksft_print_msg("Large abs latency: %lld ns :", latency/count);
123 return -1;
124 }
125
126 return 0;
127}
128
129#define SKIPPED_CLOCK_COUNT 3
130
131int main(int argc, char **argv)
132{
133 long long length;
134 int clockid, ret;
135 int max_clocks = CLOCK_TAI + 1;
136
137 ksft_print_header();
138 ksft_set_plan(max_clocks - CLOCK_REALTIME - SKIPPED_CLOCK_COUNT);
139
140 for (clockid = CLOCK_REALTIME; clockid < max_clocks; clockid++) {
141
142 /* Skip cputime clockids since nanosleep won't increment cputime */
143 if (clockid == CLOCK_PROCESS_CPUTIME_ID ||
144 clockid == CLOCK_THREAD_CPUTIME_ID ||
145 clockid == CLOCK_HWSPECIFIC)
146 continue;
147
148 length = 10;
149 while (length <= (NSEC_PER_SEC * 10)) {
150 ret = nanosleep_lat_test(clockid, length);
151 if (ret)
152 break;
153 length *= 100;
154
155 }
156
157 if (ret == UNSUPPORTED) {
158 ksft_test_result_skip("%s\n", clockstring(clockid));
159 } else {
160 ksft_test_result(ret >= 0, "%s\n",
161 clockstring(clockid));
162 }
163 }
164
165 ksft_finished();
166}
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
30static inline int ksft_exit_pass(void)
31{
32 exit(0);
33}
34static 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
61char *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
90struct 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
101long 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
109int 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
155int 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}