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Message-Id: <1424903544-26855-7-git-send-email-john.stultz@linaro.org>
Date: Wed, 25 Feb 2015 14:32:11 -0800
From: John Stultz <john.stultz@...aro.org>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: John Stultz <john.stultz@...aro.org>,
Shuah Khan <shuahkh@....samsung.com>,
Prarit Bhargava <prarit@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Richard Cochran <richardcochran@...il.com>
Subject: [PATCH 06/19] selftests/timers: Add clock skew estimation test from timetest suite
This adds my clock skew estimation test from the timetest suite.
It measures the drift between CLOCK_MONOTONIC and CLOCK_MONOTONIC_RAW
and compares it with the current frequency value from adjtimex.
It sometimes can trigger false failures when ntpd isn't in a
steady state, but its a useful too when doing adjtimex testing.
Cc: Shuah Khan <shuahkh@....samsung.com>
Cc: Prarit Bhargava <prarit@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Richard Cochran <richardcochran@...il.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
tools/testing/selftests/timers/Makefile | 3 +-
tools/testing/selftests/timers/raw_skew.c | 139 ++++++++++++++++++++++++++++++
2 files changed, 141 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/timers/raw_skew.c
diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
index 28c2184..3f41d18 100644
--- a/tools/testing/selftests/timers/Makefile
+++ b/tools/testing/selftests/timers/Makefile
@@ -1,6 +1,6 @@
CFLAGS += -O3 -Wl,-no-as-needed
LDFLAGS += -lrt -lpthread
-bins = posix_timers nanosleep inconsistency-check nsleep-lat
+bins = posix_timers nanosleep inconsistency-check nsleep-lat raw_skew
all: ${bins}
@@ -9,5 +9,6 @@ run_tests: all
./nanosleep
./nsleep-lat
./inconsistency-check
+ ./raw_skew
clean:
rm -f ${bins}
diff --git a/tools/testing/selftests/timers/raw_skew.c b/tools/testing/selftests/timers/raw_skew.c
new file mode 100644
index 0000000..997ff82
--- /dev/null
+++ b/tools/testing/selftests/timers/raw_skew.c
@@ -0,0 +1,139 @@
+/* CLOCK_MONOTONIC vs CLOCK_MONOTONIC_RAW skew test
+ * by: john stultz (johnstul@...ibm.com)
+ * John Stultz <john.stultz@...aro.org>
+ * (C) Copyright IBM 2012
+ * (C) Copyright Linaro Limited 2015
+ * Licensed under the GPLv2
+ *
+ * To build:
+ * $ gcc raw_skew.c -o raw_skew -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 <sys/time.h>
+#include <sys/timex.h>
+#include <time.h>
+
+#define CLOCK_MONOTONIC_RAW 4
+#define NSEC_PER_SEC 1000000000LL
+
+#define shift_right(x, s) ({ \
+ __typeof__(x) __x = (x); \
+ __typeof__(s) __s = (s); \
+ __x < 0 ? -(-__x >> __s) : __x >> __s; \
+})
+
+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;
+
+ 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);
+ }
+ }
+}
+
+int main(int argv, char **argc)
+{
+ struct timespec mon, raw, bound, start, end;
+ long long delta1, delta2, interval, eppm, ppm;
+ struct timex tx1, tx2;
+
+ setbuf(stdout, NULL);
+
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) {
+ printf("ERR: NO CLOCK_MONOTONIC_RAW\n");
+ return -1;
+ }
+
+ tx1.modes = 0;
+ adjtimex(&tx1);
+ get_monotonic_and_raw(&mon, &raw);
+ start = mon;
+ delta1 = diff_timespec(mon, raw);
+
+ if (tx1.offset)
+ printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n");
+
+ printf("Estimating clock drift: ");
+ sleep(120);
+
+ get_monotonic_and_raw(&mon, &raw);
+ end = mon;
+ tx2.modes = 0;
+ adjtimex(&tx2);
+ delta2 = diff_timespec(mon, raw);
+
+ interval = diff_timespec(start, end);
+
+ /* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */
+ eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval;
+ eppm = -eppm;
+ printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000)));
+
+ /* Avg the two actual freq samples adjtimex gave us */
+ ppm = (tx1.freq + tx2.freq) * 1000 / 2;
+ ppm = (long long)tx1.freq * 1000;
+ ppm = shift_right(ppm, 16);
+ printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000)));
+
+ if (llabs(eppm - ppm) > 1000) {
+ printf(" [FAILED]\n");
+ return -1;
+ }
+ printf(" [OK]\n");
+ return 0;
+}
--
1.9.1
--
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