[mirror_ubuntu-artful-kernel.git] / tools / testing / selftests / timers / freq-step.c

/*
 * This test checks the response of the system clock to frequency
 * steps made with adjtimex(). The frequency error and stability of
 * the CLOCK_MONOTONIC clock relative to the CLOCK_MONOTONIC_RAW clock
 * is measured in two intervals following the step. The test fails if
 * values from the second interval exceed specified limits.
 *
 * Copyright (C) Miroslav Lichvar <mlichvar@redhat.com>  2017
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * 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 <math.h>
#include <stdio.h>
#include <sys/timex.h>
#include <time.h>
#include <unistd.h>

#include "../kselftest.h"

#define SAMPLES 100
#define SAMPLE_READINGS 10
#define MEAN_SAMPLE_INTERVAL 0.1
#define STEP_INTERVAL 1.0
#define MAX_PRECISION 100e-9
#define MAX_FREQ_ERROR 10e-6
#define MAX_STDDEV 1000e-9

struct sample {
	double offset;
	double time;
};

static time_t mono_raw_base;
static time_t mono_base;
static long user_hz;
static double precision;
static double mono_freq_offset;

static double diff_timespec(struct timespec *ts1, struct timespec *ts2)
{
	return ts1->tv_sec - ts2->tv_sec + (ts1->tv_nsec - ts2->tv_nsec) / 1e9;
}

static double get_sample(struct sample *sample)
{
	double delay, mindelay = 0.0;
	struct timespec ts1, ts2, ts3;
	int i;

	for (i = 0; i < SAMPLE_READINGS; i++) {
		clock_gettime(CLOCK_MONOTONIC_RAW, &ts1);
		clock_gettime(CLOCK_MONOTONIC, &ts2);
		clock_gettime(CLOCK_MONOTONIC_RAW, &ts3);

		ts1.tv_sec -= mono_raw_base;
		ts2.tv_sec -= mono_base;
		ts3.tv_sec -= mono_raw_base;

		delay = diff_timespec(&ts3, &ts1);
		if (delay <= 1e-9) {
			i--;
			continue;
		}

		if (!i || delay < mindelay) {
			sample->offset = diff_timespec(&ts2, &ts1);
			sample->offset -= delay / 2.0;
			sample->time = ts1.tv_sec + ts1.tv_nsec / 1e9;
			mindelay = delay;
		}
	}

	return mindelay;
}

static void reset_ntp_error(void)
{
	struct timex txc;

	txc.modes = ADJ_SETOFFSET;
	txc.time.tv_sec = 0;
	txc.time.tv_usec = 0;

	if (adjtimex(&txc) < 0) {
		perror("[FAIL] adjtimex");
		ksft_exit_fail();
	}
}

static void set_frequency(double freq)
{
	struct timex txc;
	int tick_offset;

	tick_offset = 1e6 * freq / user_hz;

	txc.modes = ADJ_TICK | ADJ_FREQUENCY;
	txc.tick = 1000000 / user_hz + tick_offset;
	txc.freq = (1e6 * freq - user_hz * tick_offset) * (1 << 16);

	if (adjtimex(&txc) < 0) {
		perror("[FAIL] adjtimex");
		ksft_exit_fail();
	}
}

static void regress(struct sample *samples, int n, double *intercept,
		    double *slope, double *r_stddev, double *r_max)
{
	double x, y, r, x_sum, y_sum, xy_sum, x2_sum, r2_sum;
	int i;

	x_sum = 0.0, y_sum = 0.0, xy_sum = 0.0, x2_sum = 0.0;

	for (i = 0; i < n; i++) {
		x = samples[i].time;
		y = samples[i].offset;

		x_sum += x;
		y_sum += y;
		xy_sum += x * y;
		x2_sum += x * x;
	}

	*slope = (xy_sum - x_sum * y_sum / n) / (x2_sum - x_sum * x_sum / n);
	*intercept = (y_sum - *slope * x_sum) / n;

	*r_max = 0.0, r2_sum = 0.0;

	for (i = 0; i < n; i++) {
		x = samples[i].time;
		y = samples[i].offset;
		r = fabs(x * *slope + *intercept - y);
		if (*r_max < r)
			*r_max = r;
		r2_sum += r * r;
	}

	*r_stddev = sqrt(r2_sum / n);
}

static int run_test(int calibration, double freq_base, double freq_step)
{
	struct sample samples[SAMPLES];
	double intercept, slope, stddev1, max1, stddev2, max2;
	double freq_error1, freq_error2;
	int i;

	set_frequency(freq_base);

	for (i = 0; i < 10; i++)
		usleep(1e6 * MEAN_SAMPLE_INTERVAL / 10);

	reset_ntp_error();

	set_frequency(freq_base + freq_step);

	for (i = 0; i < 10; i++)
		usleep(rand() % 2000000 * STEP_INTERVAL / 10);

	set_frequency(freq_base);

	for (i = 0; i < SAMPLES; i++) {
		usleep(rand() % 2000000 * MEAN_SAMPLE_INTERVAL);
		get_sample(&samples[i]);
	}

	if (calibration) {
		regress(samples, SAMPLES, &intercept, &slope, &stddev1, &max1);
		mono_freq_offset = slope;
		printf("CLOCK_MONOTONIC_RAW frequency offset: %11.3f ppm\n",
		       1e6 * mono_freq_offset);
		return 0;
	}

	regress(samples, SAMPLES / 2, &intercept, &slope, &stddev1, &max1);
	freq_error1 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -
			freq_base;

	regress(samples + SAMPLES / 2, SAMPLES / 2, &intercept, &slope,
		&stddev2, &max2);
	freq_error2 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -
			freq_base;

	printf("%6.0f %+10.3f %6.0f %7.0f %+10.3f %6.0f %7.0f\t",
	       1e6 * freq_step,
	       1e6 * freq_error1, 1e9 * stddev1, 1e9 * max1,
	       1e6 * freq_error2, 1e9 * stddev2, 1e9 * max2);

	if (fabs(freq_error2) > MAX_FREQ_ERROR || stddev2 > MAX_STDDEV) {
		printf("[FAIL]\n");
		return 1;
	}

	printf("[OK]\n");
	return 0;
}

static void init_test(void)
{
	struct timespec ts;
	struct sample sample;

	if (clock_gettime(CLOCK_MONOTONIC_RAW, &ts)) {
		perror("[FAIL] clock_gettime(CLOCK_MONOTONIC_RAW)");
		ksft_exit_fail();
	}

	mono_raw_base = ts.tv_sec;

	if (clock_gettime(CLOCK_MONOTONIC, &ts)) {
		perror("[FAIL] clock_gettime(CLOCK_MONOTONIC)");
		ksft_exit_fail();
	}

	mono_base = ts.tv_sec;

	user_hz = sysconf(_SC_CLK_TCK);

	precision = get_sample(&sample) / 2.0;
	printf("CLOCK_MONOTONIC_RAW+CLOCK_MONOTONIC precision: %.0f ns\t\t",
	       1e9 * precision);

	if (precision > MAX_PRECISION)
		ksft_exit_skip("precision: %.0f ns > MAX_PRECISION: %.0f ns\n",
				1e9 * precision, 1e9 * MAX_PRECISION);

	printf("[OK]\n");
	srand(ts.tv_sec ^ ts.tv_nsec);

	run_test(1, 0.0, 0.0);
}

int main(int argc, char **argv)
{
	double freq_base, freq_step;
	int i, j, fails = 0;

	init_test();

	printf("Checking response to frequency step:\n");
	printf("  Step           1st interval              2nd interval\n");
	printf("             Freq    Dev     Max       Freq    Dev     Max\n");

	for (i = 2; i >= 0; i--) {
		for (j = 0; j < 5; j++) {
			freq_base = (rand() % (1 << 24) - (1 << 23)) / 65536e6;
			freq_step = 10e-6 * (1 << (6 * i));
			fails += run_test(0, freq_base, freq_step);
		}
	}

	set_frequency(0.0);

	if (fails)
		ksft_exit_fail();

	ksft_exit_pass();
}
Commit	Line	Data
76739256 ML	1	/*
	2	* This test checks the response of the system clock to frequency
	3	* steps made with adjtimex(). The frequency error and stability of
	4	* the CLOCK_MONOTONIC clock relative to the CLOCK_MONOTONIC_RAW clock
	5	* is measured in two intervals following the step. The test fails if
	6	* values from the second interval exceed specified limits.
	7	*
	8	* Copyright (C) Miroslav Lichvar <mlichvar@redhat.com> 2017
	9	*
	10	* This program is free software; you can redistribute it and/or modify
	11	* it under the terms of version 2 of the GNU General Public License as
	12	* published by the Free Software Foundation.
	13	*
	14	* This program is distributed in the hope that it will be useful, but
	15	* WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* General Public License for more details.
	18	*/
	19
	20	#include <math.h>
	21	#include <stdio.h>
	22	#include <sys/timex.h>
	23	#include <time.h>
	24	#include <unistd.h>
	25
	26	#include "../kselftest.h"
	27
	28	#define SAMPLES 100
	29	#define SAMPLE_READINGS 10
	30	#define MEAN_SAMPLE_INTERVAL 0.1
	31	#define STEP_INTERVAL 1.0
	32	#define MAX_PRECISION 100e-9
	33	#define MAX_FREQ_ERROR 10e-6
	34	#define MAX_STDDEV 1000e-9
	35
	36	struct sample {
	37	double offset;
	38	double time;
	39	};
	40
	41	static time_t mono_raw_base;
	42	static time_t mono_base;
	43	static long user_hz;
	44	static double precision;
	45	static double mono_freq_offset;
	46
	47	static double diff_timespec(struct timespec ts1, struct timespec ts2)
	48	{
	49	return ts1->tv_sec - ts2->tv_sec + (ts1->tv_nsec - ts2->tv_nsec) / 1e9;
	50	}
	51
	52	static double get_sample(struct sample *sample)
	53	{
	54	double delay, mindelay = 0.0;
	55	struct timespec ts1, ts2, ts3;
	56	int i;
	57
	58	for (i = 0; i < SAMPLE_READINGS; i++) {
	59	clock_gettime(CLOCK_MONOTONIC_RAW, &ts1);
	60	clock_gettime(CLOCK_MONOTONIC, &ts2);
	61	clock_gettime(CLOCK_MONOTONIC_RAW, &ts3);
	62
	63	ts1.tv_sec -= mono_raw_base;
	64	ts2.tv_sec -= mono_base;
65	ts3.tv_sec -= mono_raw_base;
66
67	delay = diff_timespec(&ts3, &ts1);
68	if (delay <= 1e-9) {
69	i--;
70	continue;
71	}
72
73	if (!i \|\| delay < mindelay) {
74	sample->offset = diff_timespec(&ts2, &ts1);
75	sample->offset -= delay / 2.0;
76	sample->time = ts1.tv_sec + ts1.tv_nsec / 1e9;
77	mindelay = delay;
78	}
79	}
80
81	return mindelay;
82	}
83
84	static void reset_ntp_error(void)
85	{
86	struct timex txc;
87
88	txc.modes = ADJ_SETOFFSET;
89	txc.time.tv_sec = 0;
90	txc.time.tv_usec = 0;
91
92	if (adjtimex(&txc) < 0) {
93	perror("[FAIL] adjtimex");
94	ksft_exit_fail();
95	}
96	}
97
98	static void set_frequency(double freq)
99	{
100	struct timex txc;
101	int tick_offset;
102
103	tick_offset = 1e6 * freq / user_hz;
104
105	txc.modes = ADJ_TICK \| ADJ_FREQUENCY;
106	txc.tick = 1000000 / user_hz + tick_offset;
107	txc.freq = (1e6 * freq - user_hz * tick_offset) * (1 << 16);
108
109	if (adjtimex(&txc) < 0) {
110	perror("[FAIL] adjtimex");
111	ksft_exit_fail();
112	}
113	}
114
115	static void regress(struct sample samples, int n, double intercept,
116	double slope, double r_stddev, double *r_max)
117	{
118	double x, y, r, x_sum, y_sum, xy_sum, x2_sum, r2_sum;
119	int i;
120
121	x_sum = 0.0, y_sum = 0.0, xy_sum = 0.0, x2_sum = 0.0;
122
123	for (i = 0; i < n; i++) {
124	x = samples[i].time;
125	y = samples[i].offset;
126
127	x_sum += x;
128	y_sum += y;
129	xy_sum += x * y;
130	x2_sum += x * x;
131	}
132
133	slope = (xy_sum - x_sum y_sum / n) / (x2_sum - x_sum * x_sum / n);
134	intercept = (y_sum - slope * x_sum) / n;
135
136	*r_max = 0.0, r2_sum = 0.0;
137
138	for (i = 0; i < n; i++) {
139	x = samples[i].time;
140	y = samples[i].offset;
141	r = fabs(x * slope + intercept - y);
142	if (*r_max < r)
143	*r_max = r;
144	r2_sum += r * r;
145	}
146
147	*r_stddev = sqrt(r2_sum / n);
148	}
149
150	static int run_test(int calibration, double freq_base, double freq_step)
151	{
152	struct sample samples[SAMPLES];
153	double intercept, slope, stddev1, max1, stddev2, max2;
154	double freq_error1, freq_error2;
155	int i;
156
157	set_frequency(freq_base);
158
159	for (i = 0; i < 10; i++)
160	usleep(1e6 * MEAN_SAMPLE_INTERVAL / 10);
161
162	reset_ntp_error();
163
164	set_frequency(freq_base + freq_step);
165
166	for (i = 0; i < 10; i++)
167	usleep(rand() % 2000000 * STEP_INTERVAL / 10);
168
169	set_frequency(freq_base);
170
171	for (i = 0; i < SAMPLES; i++) {
172	usleep(rand() % 2000000 * MEAN_SAMPLE_INTERVAL);
173	get_sample(&samples[i]);
174	}
175
176	if (calibration) {
177	regress(samples, SAMPLES, &intercept, &slope, &stddev1, &max1);
178	mono_freq_offset = slope;
179	printf("CLOCK_MONOTONIC_RAW frequency offset: %11.3f ppm\n",
180	1e6 * mono_freq_offset);
181	return 0;
182	}
183
184	regress(samples, SAMPLES / 2, &intercept, &slope, &stddev1, &max1);
185	freq_error1 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -
186	freq_base;
187
188	regress(samples + SAMPLES / 2, SAMPLES / 2, &intercept, &slope,
189	&stddev2, &max2);
190	freq_error2 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -
191	freq_base;
192
193	printf("%6.0f %+10.3f %6.0f %7.0f %+10.3f %6.0f %7.0f\t",
194	1e6 * freq_step,
195	1e6 * freq_error1, 1e9 * stddev1, 1e9 * max1,
196	1e6 * freq_error2, 1e9 * stddev2, 1e9 * max2);
197
198	if (fabs(freq_error2) > MAX_FREQ_ERROR \|\| stddev2 > MAX_STDDEV) {
199	printf("[FAIL]\n");
200	return 1;
201	}
202
203	printf("[OK]\n");
204	return 0;
205	}
206
207	static void init_test(void)
208	{
209	struct timespec ts;
210	struct sample sample;
211
212	if (clock_gettime(CLOCK_MONOTONIC_RAW, &ts)) {
213	perror("[FAIL] clock_gettime(CLOCK_MONOTONIC_RAW)");
214	ksft_exit_fail();
215	}
216
217	mono_raw_base = ts.tv_sec;
218
219	if (clock_gettime(CLOCK_MONOTONIC, &ts)) {
220	perror("[FAIL] clock_gettime(CLOCK_MONOTONIC)");
221	ksft_exit_fail();
222	}
223
224	mono_base = ts.tv_sec;
225
226	user_hz = sysconf(_SC_CLK_TCK);
227
228	precision = get_sample(&sample) / 2.0;
229	printf("CLOCK_MONOTONIC_RAW+CLOCK_MONOTONIC precision: %.0f ns\t\t",
230	1e9 * precision);
231
622b2fbe SK	232	if (precision > MAX_PRECISION)
	233	ksft_exit_skip("precision: %.0f ns > MAX_PRECISION: %.0f ns\n",
	234	1e9 * precision, 1e9 * MAX_PRECISION);
76739256 ML	235
	236	printf("[OK]\n");
	237	srand(ts.tv_sec ^ ts.tv_nsec);
	238
	239	run_test(1, 0.0, 0.0);
	240	}
	241
	242	int main(int argc, char **argv)
	243	{
	244	double freq_base, freq_step;
	245	int i, j, fails = 0;
	246
	247	init_test();
	248
	249	printf("Checking response to frequency step:\n");
	250	printf(" Step 1st interval 2nd interval\n");
	251	printf(" Freq Dev Max Freq Dev Max\n");
	252
	253	for (i = 2; i >= 0; i--) {
	254	for (j = 0; j < 5; j++) {
	255	freq_base = (rand() % (1 << 24) - (1 << 23)) / 65536e6;
	256	freq_step = 10e-6 * (1 << (6 * i));
	257	fails += run_test(0, freq_base, freq_step);
	258	}
	259	}
	260
	261	set_frequency(0.0);
	262
	263	if (fails)
	264	ksft_exit_fail();
	265
	266	ksft_exit_pass();
	267	}