diff options
Diffstat (limited to 'tools/testing/selftests/timers/nsleep-lat.c')
| -rw-r--r-- | tools/testing/selftests/timers/nsleep-lat.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/tools/testing/selftests/timers/nsleep-lat.c b/tools/testing/selftests/timers/nsleep-lat.c new file mode 100644 index 0000000..2d7898f --- /dev/null +++ b/tools/testing/selftests/timers/nsleep-lat.c @@ -0,0 +1,190 @@ +/* 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> +#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 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)); + + 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(); +} |