enable optimal defaults on linux kernels that can support newer features.

src/switch_core.c

@@ -1662,9 +1662,6 @@ static void switch_load_core_config(const char *file)
 					switch_time_set_monotonic(switch_true(val));
 				} else if (!strcasecmp(var, "enable-softtimer-timerfd")) {
 					switch_time_set_timerfd(switch_true(val));
-					if (switch_true(val)) {
-						switch_clear_flag((&runtime), SCF_CALIBRATE_CLOCK);
-					}
 				} else if (!strcasecmp(var, "enable-clock-nanosleep")) {
 					switch_time_set_nanosleep(switch_true(val));
 				} else if (!strcasecmp(var, "enable-cond-yield")) {

src/switch_time.c

@@ -61,14 +61,20 @@ static int MONO = 1;
 static int MONO = 0;
 #endif
 
+/* clock_nanosleep works badly on some kernels but really well on others.
+   timerfd seems to work well as long as it exists so if you have timerfd we'll also enable clock_nanosleep by default.
+*/
 #if defined(HAVE_TIMERFD_CREATE)
-// We'll default this to 1 after we have had some positive feedback that it works well
-static int TFD = 0;
+static int TFD = 1;
+#if defined(HAVE_CLOCK_NANOSLEEP)
+static int NANO = 1;
 #else
-static int TFD = 0;
+static int NANO = 0;
 #endif
-
+#else
+static int TFD = 0;
 static int NANO = 0;
+#endif
 
 static int OFFSET = 0;
 
@@ -326,6 +332,7 @@ SWITCH_DECLARE(void) switch_time_set_timerfd(switch_bool_t enable)
 #if defined(HAVE_TIMERFD_CREATE)
 	TFD = enable ? 1 : 0;
 	switch_time_sync();
+
 #else
 	TFD = 0;
 #endif
@@ -1116,6 +1123,10 @@ SWITCH_MODULE_LOAD_FUNCTION(softtimer_load)
 		switch_time_set_cond_yield(SWITCH_FALSE);
 	}
 
+	if (TFD) {
+		switch_clear_flag((&runtime), SCF_CALIBRATE_CLOCK);
+	}
+
 	if (switch_test_flag((&runtime), SCF_CALIBRATE_CLOCK)) {
 		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_CONSOLE, "Calibrating timer, please wait...\n");
 		switch_time_calibrate_clock();