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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * This test checks the response of the system clock to frequency4 * steps made with adjtimex(). The frequency error and stability of5 * the CLOCK_MONOTONIC clock relative to the CLOCK_MONOTONIC_RAW clock6 * is measured in two intervals following the step. The test fails if7 * values from the second interval exceed specified limits.8 *9 * Copyright (C) Miroslav Lichvar <mlichvar@redhat.com> 201710 */11 12#include <math.h>13#include <stdio.h>14#include <sys/timex.h>15#include <time.h>16#include <unistd.h>17 18#include "../kselftest.h"19 20#define SAMPLES 10021#define SAMPLE_READINGS 1022#define MEAN_SAMPLE_INTERVAL 0.123#define STEP_INTERVAL 1.024#define MAX_PRECISION 500e-925#define MAX_FREQ_ERROR 0.02e-626#define MAX_STDDEV 50e-927 28#ifndef ADJ_SETOFFSET29 #define ADJ_SETOFFSET 0x010030#endif31 32struct sample {33 double offset;34 double time;35};36 37static time_t mono_raw_base;38static time_t mono_base;39static long user_hz;40static double precision;41static double mono_freq_offset;42 43static double diff_timespec(struct timespec *ts1, struct timespec *ts2)44{45 return ts1->tv_sec - ts2->tv_sec + (ts1->tv_nsec - ts2->tv_nsec) / 1e9;46}47 48static double get_sample(struct sample *sample)49{50 double delay, mindelay = 0.0;51 struct timespec ts1, ts2, ts3;52 int i;53 54 for (i = 0; i < SAMPLE_READINGS; i++) {55 clock_gettime(CLOCK_MONOTONIC_RAW, &ts1);56 clock_gettime(CLOCK_MONOTONIC, &ts2);57 clock_gettime(CLOCK_MONOTONIC_RAW, &ts3);58 59 ts1.tv_sec -= mono_raw_base;60 ts2.tv_sec -= mono_base;61 ts3.tv_sec -= mono_raw_base;62 63 delay = diff_timespec(&ts3, &ts1);64 if (delay <= 1e-9) {65 i--;66 continue;67 }68 69 if (!i || delay < mindelay) {70 sample->offset = diff_timespec(&ts2, &ts1);71 sample->offset -= delay / 2.0;72 sample->time = ts1.tv_sec + ts1.tv_nsec / 1e9;73 mindelay = delay;74 }75 }76 77 return mindelay;78}79 80static void reset_ntp_error(void)81{82 struct timex txc;83 84 txc.modes = ADJ_SETOFFSET;85 txc.time.tv_sec = 0;86 txc.time.tv_usec = 0;87 88 if (adjtimex(&txc) < 0) {89 perror("[FAIL] adjtimex");90 ksft_exit_fail();91 }92}93 94static void set_frequency(double freq)95{96 struct timex txc;97 int tick_offset;98 99 tick_offset = 1e6 * freq / user_hz;100 101 txc.modes = ADJ_TICK | ADJ_FREQUENCY;102 txc.tick = 1000000 / user_hz + tick_offset;103 txc.freq = (1e6 * freq - user_hz * tick_offset) * (1 << 16);104 105 if (adjtimex(&txc) < 0) {106 perror("[FAIL] adjtimex");107 ksft_exit_fail();108 }109}110 111static void regress(struct sample *samples, int n, double *intercept,112 double *slope, double *r_stddev, double *r_max)113{114 double x, y, r, x_sum, y_sum, xy_sum, x2_sum, r2_sum;115 int i;116 117 x_sum = 0.0, y_sum = 0.0, xy_sum = 0.0, x2_sum = 0.0;118 119 for (i = 0; i < n; i++) {120 x = samples[i].time;121 y = samples[i].offset;122 123 x_sum += x;124 y_sum += y;125 xy_sum += x * y;126 x2_sum += x * x;127 }128 129 *slope = (xy_sum - x_sum * y_sum / n) / (x2_sum - x_sum * x_sum / n);130 *intercept = (y_sum - *slope * x_sum) / n;131 132 *r_max = 0.0, r2_sum = 0.0;133 134 for (i = 0; i < n; i++) {135 x = samples[i].time;136 y = samples[i].offset;137 r = fabs(x * *slope + *intercept - y);138 if (*r_max < r)139 *r_max = r;140 r2_sum += r * r;141 }142 143 *r_stddev = sqrt(r2_sum / n);144}145 146static int run_test(int calibration, double freq_base, double freq_step)147{148 struct sample samples[SAMPLES];149 double intercept, slope, stddev1, max1, stddev2, max2;150 double freq_error1, freq_error2;151 int i;152 153 set_frequency(freq_base);154 155 for (i = 0; i < 10; i++)156 usleep(1e6 * MEAN_SAMPLE_INTERVAL / 10);157 158 reset_ntp_error();159 160 set_frequency(freq_base + freq_step);161 162 for (i = 0; i < 10; i++)163 usleep(rand() % 2000000 * STEP_INTERVAL / 10);164 165 set_frequency(freq_base);166 167 for (i = 0; i < SAMPLES; i++) {168 usleep(rand() % 2000000 * MEAN_SAMPLE_INTERVAL);169 get_sample(&samples[i]);170 }171 172 if (calibration) {173 regress(samples, SAMPLES, &intercept, &slope, &stddev1, &max1);174 mono_freq_offset = slope;175 printf("CLOCK_MONOTONIC_RAW frequency offset: %11.3f ppm\n",176 1e6 * mono_freq_offset);177 return 0;178 }179 180 regress(samples, SAMPLES / 2, &intercept, &slope, &stddev1, &max1);181 freq_error1 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -182 freq_base;183 184 regress(samples + SAMPLES / 2, SAMPLES / 2, &intercept, &slope,185 &stddev2, &max2);186 freq_error2 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -187 freq_base;188 189 printf("%6.0f %+10.3f %6.0f %7.0f %+10.3f %6.0f %7.0f\t",190 1e6 * freq_step,191 1e6 * freq_error1, 1e9 * stddev1, 1e9 * max1,192 1e6 * freq_error2, 1e9 * stddev2, 1e9 * max2);193 194 if (fabs(freq_error2) > MAX_FREQ_ERROR || stddev2 > MAX_STDDEV) {195 printf("[FAIL]\n");196 return 1;197 }198 199 printf("[OK]\n");200 return 0;201}202 203static void init_test(void)204{205 struct timespec ts;206 struct sample sample;207 208 if (clock_gettime(CLOCK_MONOTONIC_RAW, &ts)) {209 perror("[FAIL] clock_gettime(CLOCK_MONOTONIC_RAW)");210 ksft_exit_fail();211 }212 213 mono_raw_base = ts.tv_sec;214 215 if (clock_gettime(CLOCK_MONOTONIC, &ts)) {216 perror("[FAIL] clock_gettime(CLOCK_MONOTONIC)");217 ksft_exit_fail();218 }219 220 mono_base = ts.tv_sec;221 222 user_hz = sysconf(_SC_CLK_TCK);223 224 precision = get_sample(&sample) / 2.0;225 printf("CLOCK_MONOTONIC_RAW+CLOCK_MONOTONIC precision: %.0f ns\t\t",226 1e9 * precision);227 228 if (precision > MAX_PRECISION)229 ksft_exit_skip("precision: %.0f ns > MAX_PRECISION: %.0f ns\n",230 1e9 * precision, 1e9 * MAX_PRECISION);231 232 printf("[OK]\n");233 srand(ts.tv_sec ^ ts.tv_nsec);234 235 run_test(1, 0.0, 0.0);236}237 238int main(int argc, char **argv)239{240 double freq_base, freq_step;241 int i, j, fails = 0;242 243 init_test();244 245 printf("Checking response to frequency step:\n");246 printf(" Step 1st interval 2nd interval\n");247 printf(" Freq Dev Max Freq Dev Max\n");248 249 for (i = 2; i >= 0; i--) {250 for (j = 0; j < 5; j++) {251 freq_base = (rand() % (1 << 24) - (1 << 23)) / 65536e6;252 freq_step = 10e-6 * (1 << (6 * i));253 fails += run_test(0, freq_base, freq_step);254 }255 }256 257 set_frequency(0.0);258 259 if (fails)260 ksft_exit_fail();261 262 ksft_exit_pass();263}264