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    Subject[PATCH 05/19] selftests/timers: Add nsleep-lat test from timetest suite
    Date
    Adds my nanosleep latency test from the timetest suite.
    This checks to make sure we don't see "unreasonable"
    latencies (> 40ms) when calling nanosleep.

    Cc: Shuah Khan <shuahkh@osg.samsung.com>
    Cc: Prarit Bhargava <prarit@redhat.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Richard Cochran <richardcochran@gmail.com>
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    ---
    tools/testing/selftests/timers/Makefile | 3 +-
    tools/testing/selftests/timers/nsleep-lat.c | 190 ++++++++++++++++++++++++++++
    2 files changed, 192 insertions(+), 1 deletion(-)
    create mode 100644 tools/testing/selftests/timers/nsleep-lat.c

    diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
    index fcb7c2f..dae9ee7 100644
    --- a/tools/testing/selftests/timers/Makefile
    +++ b/tools/testing/selftests/timers/Makefile
    @@ -2,13 +2,14 @@ CC = $(CROSS_COMPILE)gcc
    BUILD_FLAGS = -DKTEST
    CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)
    LDFLAGS += -lrt -lpthread
    -bins = posix_timers nanosleep inconsistency-check
    +bins = posix_timers nanosleep inconsistency-check nsleep-lat

    all: ${bins}

    run_tests: all
    ./posix_timers
    ./nanosleep
    + ./nsleep-lat
    ./inconsistency-check
    clean:
    rm -f ${bins}
    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();
    +}
    --
    1.9.1


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