diff options
Diffstat (limited to 'kernel/tools/testing/selftests/timers/adjtick.c')
| -rw-r--r-- | kernel/tools/testing/selftests/timers/adjtick.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/kernel/tools/testing/selftests/timers/adjtick.c b/kernel/tools/testing/selftests/timers/adjtick.c new file mode 100644 index 000000000..9887fd538 --- /dev/null +++ b/kernel/tools/testing/selftests/timers/adjtick.c @@ -0,0 +1,221 @@ +/* adjtimex() tick adjustment test + * by: John Stultz <john.stultz@linaro.org> + * (C) Copyright Linaro Limited 2015 + * Licensed under the GPLv2 + * + * To build: + * $ gcc adjtick.c -o adjtick -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 <unistd.h> +#include <stdlib.h> +#include <sys/time.h> +#include <sys/timex.h> +#include <time.h> + +#ifdef KTEST +#include "../kselftest.h" +#else +static inline int ksft_exit_pass(void) +{ + exit(0); +} +static inline int ksft_exit_fail(void) +{ + exit(1); +} +#endif + +#define CLOCK_MONOTONIC_RAW 4 + +#define NSEC_PER_SEC 1000000000LL +#define USEC_PER_SEC 1000000 + +#define MILLION 1000000 + +long systick; + +long long llabs(long long val) +{ + if (val < 0) + val = -val; + return val; +} + +unsigned long long ts_to_nsec(struct timespec ts) +{ + return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; +} + +struct timespec nsec_to_ts(long long ns) +{ + struct timespec ts; + + ts.tv_sec = ns/NSEC_PER_SEC; + ts.tv_nsec = ns%NSEC_PER_SEC; + + return ts; +} + +long long diff_timespec(struct timespec start, struct timespec end) +{ + long long start_ns, end_ns; + + start_ns = ts_to_nsec(start); + end_ns = ts_to_nsec(end); + + return end_ns - start_ns; +} + +void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw) +{ + struct timespec start, mid, end; + long long diff = 0, tmp; + int i; + + clock_gettime(CLOCK_MONOTONIC, mon); + clock_gettime(CLOCK_MONOTONIC_RAW, raw); + + /* Try to get a more tightly bound pairing */ + for (i = 0; i < 3; i++) { + long long newdiff; + + clock_gettime(CLOCK_MONOTONIC, &start); + clock_gettime(CLOCK_MONOTONIC_RAW, &mid); + clock_gettime(CLOCK_MONOTONIC, &end); + + newdiff = diff_timespec(start, end); + if (diff == 0 || newdiff < diff) { + diff = newdiff; + *raw = mid; + tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2; + *mon = nsec_to_ts(tmp); + } + } +} + +long long get_ppm_drift(void) +{ + struct timespec mon_start, raw_start, mon_end, raw_end; + long long delta1, delta2, eppm; + + get_monotonic_and_raw(&mon_start, &raw_start); + + sleep(15); + + get_monotonic_and_raw(&mon_end, &raw_end); + + delta1 = diff_timespec(mon_start, mon_end); + delta2 = diff_timespec(raw_start, raw_end); + + eppm = (delta1*MILLION)/delta2 - MILLION; + + return eppm; +} + +int check_tick_adj(long tickval) +{ + long long eppm, ppm; + struct timex tx1; + + tx1.modes = ADJ_TICK; + tx1.modes |= ADJ_OFFSET; + tx1.modes |= ADJ_FREQUENCY; + tx1.modes |= ADJ_STATUS; + + tx1.status = STA_PLL; + tx1.offset = 0; + tx1.freq = 0; + tx1.tick = tickval; + + adjtimex(&tx1); + + sleep(1); + + ppm = ((long long)tickval * MILLION)/systick - MILLION; + printf("Estimating tick (act: %ld usec, %lld ppm): ", tickval, ppm); + + eppm = get_ppm_drift(); + printf("%lld usec, %lld ppm", systick + (systick * eppm / MILLION), eppm); + + tx1.modes = 0; + adjtimex(&tx1); + + if (tx1.offset || tx1.freq || tx1.tick != tickval) { + printf(" [ERROR]\n"); + printf("\tUnexpected adjtimex return values, make sure ntpd is not running.\n"); + return -1; + } + + /* + * Here we use 100ppm difference as an error bound. + * We likely should see better, but some coarse clocksources + * cannot match the HZ tick size accurately, so we have a + * internal correction factor that doesn't scale exactly + * with the adjustment, resulting in > 10ppm error during + * a 10% adjustment. 100ppm also gives us more breathing + * room for interruptions during the measurement. + */ + if (llabs(eppm - ppm) > 100) { + printf(" [FAILED]\n"); + return -1; + } + printf(" [OK]\n"); + + return 0; +} + +int main(int argv, char **argc) +{ + struct timespec raw; + long tick, max, interval, err; + struct timex tx1; + + err = 0; + setbuf(stdout, NULL); + + if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) { + printf("ERR: NO CLOCK_MONOTONIC_RAW\n"); + return -1; + } + + printf("Each iteration takes about 15 seconds\n"); + + systick = sysconf(_SC_CLK_TCK); + systick = USEC_PER_SEC/sysconf(_SC_CLK_TCK); + max = systick/10; /* +/- 10% */ + interval = max/4; /* in 4 steps each side */ + + for (tick = (systick - max); tick < (systick + max); tick += interval) { + if (check_tick_adj(tick)) { + err = 1; + break; + } + } + + /* Reset things to zero */ + tx1.modes = ADJ_TICK; + tx1.modes |= ADJ_OFFSET; + tx1.modes |= ADJ_FREQUENCY; + + tx1.offset = 0; + tx1.freq = 0; + tx1.tick = systick; + + adjtimex(&tx1); + + if (err) + return ksft_exit_fail(); + + return ksft_exit_pass(); +} |