selftests/timers: Add nsleep-lat test from timetest suite

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>
Tested-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

2 files changed, 192 insertions, 1 deletions

diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
index fcb7c2fcafe5..dae9ee76b74b 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 000000000000..2d7898fda0f1
--- /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();
+}