aboutsummaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/timers/nsleep-lat.c
blob: eb3e79ed7b4a9eb5b58b332490b51f1f2a0db204 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
/* Measure nanosleep timer latency
 *              by: john stultz (john.stultz@linaro.org)
 *		(C) Copyright Linaro 2013
 *              Licensed under the GPLv2
 *
 *  To build:
 *	$ gcc nsleep-lat.c -o nsleep-lat -lrt
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
#include "../kselftest.h"

#define NSEC_PER_SEC 1000000000ULL

#define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */


#define CLOCK_REALTIME			0
#define CLOCK_MONOTONIC			1
#define CLOCK_PROCESS_CPUTIME_ID	2
#define CLOCK_THREAD_CPUTIME_ID		3
#define CLOCK_MONOTONIC_RAW		4
#define CLOCK_REALTIME_COARSE		5
#define CLOCK_MONOTONIC_COARSE		6
#define CLOCK_BOOTTIME			7
#define CLOCK_REALTIME_ALARM		8
#define CLOCK_BOOTTIME_ALARM		9
#define CLOCK_HWSPECIFIC		10
#define CLOCK_TAI			11
#define NR_CLOCKIDS			12

#define UNSUPPORTED 0xf00f

char *clockstring(int clockid)
{
	switch (clockid) {
	case CLOCK_REALTIME:
		return "CLOCK_REALTIME";
	case CLOCK_MONOTONIC:
		return "CLOCK_MONOTONIC";
	case CLOCK_PROCESS_CPUTIME_ID:
		return "CLOCK_PROCESS_CPUTIME_ID";
	case CLOCK_THREAD_CPUTIME_ID:
		return "CLOCK_THREAD_CPUTIME_ID";
	case CLOCK_MONOTONIC_RAW:
		return "CLOCK_MONOTONIC_RAW";
	case CLOCK_REALTIME_COARSE:
		return "CLOCK_REALTIME_COARSE";
	case CLOCK_MONOTONIC_COARSE:
		return "CLOCK_MONOTONIC_COARSE";
	case CLOCK_BOOTTIME:
		return "CLOCK_BOOTTIME";
	case CLOCK_REALTIME_ALARM:
		return "CLOCK_REALTIME_ALARM";
	case CLOCK_BOOTTIME_ALARM:
		return "CLOCK_BOOTTIME_ALARM";
	case CLOCK_TAI:
		return "CLOCK_TAI";
	};
	return "UNKNOWN_CLOCKID";
}

struct timespec timespec_add(struct timespec ts, unsigned long long ns)
{
	ts.tv_nsec += ns;
	while (ts.tv_nsec >= NSEC_PER_SEC) {
		ts.tv_nsec -= NSEC_PER_SEC;
		ts.tv_sec++;
	}
	return ts;
}


long long timespec_sub(struct timespec a, struct timespec b)
{
	long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;

	ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
	return ret;
}

int nanosleep_lat_test(int clockid, long long ns)
{
	struct timespec start, end, target;
	long long latency = 0;
	int i, count;

	target.tv_sec = ns/NSEC_PER_SEC;
	target.tv_nsec = ns%NSEC_PER_SEC;

	if (clock_gettime(clockid, &start))
		return UNSUPPORTED;
	if (clock_nanosleep(clockid, 0, &target, NULL))
		return UNSUPPORTED;

	count = 10;

	/* First check relative latency */
	clock_gettime(clockid, &start);
	for (i = 0; i < count; i++)
		clock_nanosleep(clockid, 0, &target, NULL);
	clock_gettime(clockid, &end);

	if (((timespec_sub(start, end)/count)-ns) > UNRESONABLE_LATENCY) {
		printf("Large rel latency: %lld ns :", (timespec_sub(start, end)/count)-ns);
		return -1;
	}

	/* Next check absolute latency */
	for (i = 0; i < count; i++) {
		clock_gettime(clockid, &start);
		target = timespec_add(start, ns);
		clock_nanosleep(clockid, TIMER_ABSTIME, &target, NULL);
		clock_gettime(clockid, &end);
		latency += timespec_sub(target, end);
	}

	if (latency/count > UNRESONABLE_LATENCY) {
		printf("Large abs latency: %lld ns :", latency/count);
		return -1;
	}

	return 0;
}



int main(int argc, char **argv)
{
	long long length;
	int clockid, ret;

	for (clockid = CLOCK_REALTIME; clockid < NR_CLOCKIDS; clockid++) {

		/* Skip cputime clockids since nanosleep won't increment cputime */
		if (clockid == CLOCK_PROCESS_CPUTIME_ID ||
				clockid == CLOCK_THREAD_CPUTIME_ID ||
				clockid == CLOCK_HWSPECIFIC)
			continue;

		printf("nsleep latency %-26s ", clockstring(clockid));
		fflush(stdout);

		length = 10;
		while (length <= (NSEC_PER_SEC * 10)) {
			ret = nanosleep_lat_test(clockid, length);
			if (ret)
				break;
			length *= 100;

		}

		if (ret == UNSUPPORTED) {
			printf("[UNSUPPORTED]\n");
			continue;
		}
		if (ret < 0) {
			printf("[FAILED]\n");
			return ksft_exit_fail();
		}
		printf("[OK]\n");
	}
	return ksft_exit_pass();
}