@@ -1,12 +1,13 @@
CFLAGS += -O3 -Wl,-no-as-needed
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}
new file mode 100644
@@ -0,0 +1,178 @@
+/* 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>
+
+#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 failed = 0, 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 -1;
+ }
+ printf("[OK]\n");
+ }
+ return 0;
+}
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 | 178 ++++++++++++++++++++++++++++ 2 files changed, 180 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/timers/nsleep-lat.c