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[76.115.103.22]) by smtp.gmail.com with ESMTPSA id fx4sm29847730pbb.92.2015.10.05.18.17.01 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 05 Oct 2015 18:17:01 -0700 (PDT) From: John Stultz To: linux-kernel@vger.kernel.org Cc: John Stultz , =?UTF-8?q?Nuno=20Gon=C3=A7alves?= , Miroslav Lichvar , Prarit Bhargava , Richard Cochran , Ingo Molnar , Thomas Gleixner , Shuah Khan Subject: [PATCH v4] kselftest: timers: Add adjtick test to validate adjtimex() tick adjustments Date: Mon, 5 Oct 2015 18:16:57 -0700 Message-Id: <1444094217-20258-1-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: john.stultz@linaro.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of patch+caf_=patchwork-forward=linaro.org@linaro.org designates 209.85.215.49 as permitted sender) smtp.mailfrom=patch+caf_=patchwork-forward=linaro.org@linaro.org Precedence: list Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org List-ID: X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , Recently an issue was reported that was difficult to detect except by tweaking the adjtimex tick value, and noticing how quickly the adjustment took to be made: https://lkml.org/lkml/2015/9/1/488 Thus this patch introduces a new test which manipulates the adjtimex tick value and validates the results are what we expect. Cc: Nuno Gonçalves Cc: Miroslav Lichvar Cc: Prarit Bhargava Cc: Richard Cochran Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Shuah Khan Signed-off-by: John Stultz --- v2: - Use sysconf(_SC_CLK_TCK) to properly get USER_HZ value. v3: - Set STA_PLL to ensure offset is cleared - Add rational for 100ppm error bound v4: - Add message informing each iteration takes ~15 secs - Cleanup error message when ntpd is suspected of running tools/testing/selftests/timers/Makefile | 3 +- tools/testing/selftests/timers/adjtick.c | 210 +++++++++++++++++++++++++++++++ 2 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/timers/adjtick.c diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile index 89a3f44..4a1be1b 100644 --- a/tools/testing/selftests/timers/Makefile +++ b/tools/testing/selftests/timers/Makefile @@ -8,7 +8,7 @@ LDFLAGS += -lrt -lpthread TEST_PROGS = posix_timers nanosleep nsleep-lat set-timer-lat mqueue-lat \ inconsistency-check raw_skew threadtest rtctest -TEST_PROGS_EXTENDED = alarmtimer-suspend valid-adjtimex change_skew \ +TEST_PROGS_EXTENDED = alarmtimer-suspend valid-adjtimex adjtick change_skew \ skew_consistency clocksource-switch leap-a-day \ leapcrash set-tai set-2038 @@ -24,6 +24,7 @@ include ../lib.mk run_destructive_tests: run_tests ./alarmtimer-suspend ./valid-adjtimex + ./adjtick ./change_skew ./skew_consistency ./clocksource-switch diff --git a/tools/testing/selftests/timers/adjtick.c b/tools/testing/selftests/timers/adjtick.c new file mode 100644 index 0000000..253f684 --- /dev/null +++ b/tools/testing/selftests/timers/adjtick.c @@ -0,0 +1,210 @@ +/* adjtimex() tick adjustment test + * by: John Stultz + * (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 +#include +#include +#include +#include +#include +#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(); +}