From d314f25424cb8ce50c1fe15e28b4162fc792b8b2 Mon Sep 17 00:00:00 2001
From: Anthony Minessale <anthony.minessale@gmail.com>
Date: Wed, 13 Jan 2010 21:07:39 +0000
Subject: [PATCH] update timer calibration

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@16290 d0543943-73ff-0310-b7d9-9358b9ac24b2
---
 configure.in      |  1 +
 src/switch_time.c | 22 ++++++++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/configure.in b/configure.in
index 0a330366b4..c0dbeb5c08 100644
--- a/configure.in
+++ b/configure.in
@@ -437,6 +437,7 @@ AC_CHECK_FUNCS([wcsncmp setgroups asprintf setenv pselect gettimeofday localtime
 AX_HAVE_CPU_SET
 
 AC_CHECK_LIB(rt, clock_gettime, [AC_DEFINE(HAVE_CLOCK_GETTIME, 1, [Define if you have clock_gettime()])])
+AC_CHECK_LIB(rt, clock_getres, [AC_DEFINE(HAVE_CLOCK_GETRES, 1, [Define if you have clock_getres()])])
 AC_CHECK_LIB(rt, clock_nanosleep, [AC_DEFINE(HAVE_CLOCK_NANOSLEEP, 1, [Define if you have clock_nanosleep()])])
 AC_CHECK_FUNC(socket, , AC_CHECK_LIB(socket, socket))
 
diff --git a/src/switch_time.c b/src/switch_time.c
index 0e44a8fd91..ab2f03e711 100644
--- a/src/switch_time.c
+++ b/src/switch_time.c
@@ -181,13 +181,31 @@ static void calibrate_clock(void)
 {
 	int x;
 	switch_interval_time_t avg, val = 1000, want = 1000;
-	int over = 0, under = 0, good = 0, step = 50;
+	int over = 0, under = 0, good = 0, step = 50, diff = 0;
+
+#ifdef HAVE_CLOCK_GETRES
+	struct timespec ts;
+	clock_getres(CLOCK_MONOTONIC, &ts);
+	if (ts.tv_nsec / 1000 > 1500) {
+		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, 
+						  "Timer resolution of %ld microseconds detected do you have your kernel timer set to higher than 1khz?\n", ts.tv_nsec / 1000);
+		return;
+	}
+#endif
 
 	for (x = 0; x < 500; x++) {
 		avg = average_time(val, 100);
 		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_CONSOLE, "Test: %ld Average: %ld Step: %d\n", val, avg, step);
 
-		if (abs((int)(want - avg)) <= 2) {
+		diff = abs((int)(want - avg));
+		if (diff > 1500) {
+			switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, 
+							  "Abnormally large timer gap detected, do you have your kernel timer set to higher than 1khz?\n");
+			return;
+		}
+
+
+		if (diff <= 2) {
 			under = over = 0;
 			if (++good > 10) {
 				break;