From 082f3f91cf75aeda6889c0b61109ce1604f3b875 Mon Sep 17 00:00:00 2001
From: Richard Fuchs <rfuchs@sipwise.com>
Date: Wed, 5 Mar 2025 12:46:05 -0400
Subject: [PATCH] MT#55283 add timer-accuracy= option

Change-Id: I32eb05a5eaacccd2ef3e553a90a1eada33a9f50d
---
 daemon/main.c        | 5 +++++
 daemon/timerthread.c | 5 ++++-
 docs/rtpengine.md    | 8 ++++++++
 include/main.h       | 1 +
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/daemon/main.c b/daemon/main.c
index 2a402aac2..b9d418a04 100644
--- a/daemon/main.c
+++ b/daemon/main.c
@@ -121,6 +121,7 @@ struct rtpengine_config rtpe_config = {
 	},
 	.max_recv_iters = MAX_RECV_ITERS,
 	.kernel_player_media = 128,
+	.timer_accuracy = 500,
 };
 
 struct interface_config_callback_arg {
@@ -738,6 +739,7 @@ static void options(int *argc, char ***argv, charp_ht templates) {
 		{ "http-threads", 0,0,	G_OPTION_ARG_INT,	&rtpe_config.http_threads,"Number of worker threads for HTTP and WS","INT"},
 		{ "software-id", 0,0,	G_OPTION_ARG_STRING,	&rtpe_config.software_id,"Identification string of this software presented to external systems","STRING"},
 		{ "poller-per-thread", 0,0,	G_OPTION_ARG_NONE,	&rtpe_config.poller_per_thread,	"Use poller per thread",	NULL },
+		{ "timer-accuracy", 0,0,G_OPTION_ARG_INT,	&rtpe_config.timer_accuracy,"Minimum number of microseconds to sleep","INT"},
 #ifdef WITH_TRANSCODING
 		{ "dtx-delay",	0,0,	G_OPTION_ARG_INT,	&rtpe_config.dtx_delay,	"Delay in milliseconds to trigger DTX handling","INT"},
 		{ "max-dtx",	0,0,	G_OPTION_ARG_INT,	&rtpe_config.max_dtx,	"Maximum duration of DTX handling",	"INT"},
@@ -1280,6 +1282,9 @@ static void options(int *argc, char ***argv, charp_ht templates) {
 			die("Number of CPU cores is unknown, cannot auto-set socket CPU affinity");
 	}
 
+	if (rtpe_config.timer_accuracy < 0)
+		die("Invalid --timer-accuracy value (%d)", rtpe_config.timer_accuracy);
+
 	// everything OK, do post-processing
 
 }
diff --git a/daemon/timerthread.c b/daemon/timerthread.c
index 7e30b91c8..58f1139d4 100644
--- a/daemon/timerthread.c
+++ b/daemon/timerthread.c
@@ -3,6 +3,7 @@
 #include "helpers.h"
 #include "log_funcs.h"
 #include "poller.h"
+#include "main.h"
 
 
 static int tt_obj_cmp(const void *a, const void *b) {
@@ -55,6 +56,8 @@ static void timerthread_run(void *p) {
 	struct thread_waker waker = { .lock = &tt->lock, .cond = &tt->cond };
 	thread_waker_add(&waker);
 
+	long long accuracy = rtpe_config.timer_accuracy;
+
 	mutex_lock(&tt->lock);
 
 	while (!rtpe_shutdown) {
@@ -76,7 +79,7 @@ static void timerthread_run(void *p) {
 		// scheduled to run? if not, then we remember this object/reference and go to sleep
 		sleeptime = timeval_diff(&tt_obj->next_check, &rtpe_now);
 
-		if (sleeptime > 0) {
+		if (sleeptime > accuracy) {
 			tt->obj = tt_obj;
 			goto sleep;
 		}
diff --git a/docs/rtpengine.md b/docs/rtpengine.md
index b23ade206..90f9560f9 100644
--- a/docs/rtpengine.md
+++ b/docs/rtpengine.md
@@ -1322,6 +1322,14 @@ call to inject-DTMF won't be sent to __\-\-dtmf-log-dest=__ or __\-\-listen-tcp-
     thus maintaining the order of the packets. Might help when having issues with
     DTMF packets (RFC 2833).
 
+- __\-\-timer-accuracy=__*INT*
+
+    Minimum number of microseconds that a timer thread is allowed to sleep. In
+    other words, if a timed event is scheduled sooner than this many
+    microseconds in the future, then the event will be executed immediately.
+    Set to zero for highest accuracy. Default is 500 microseconds (half a
+    millisecond).
+
 - __\-\-io-uring__
 
     Enable **experimental** support for `io_uring`. Requires Linux kernel 6.0
diff --git a/include/main.h b/include/main.h
index 5636c4008..515255d24 100644
--- a/include/main.h
+++ b/include/main.h
@@ -99,6 +99,7 @@ enum endpoint_learning {
 	X(media_expire) \
 	X(db_expire) \
 	X(cache_expire) \
+	X(timer_accuracy) \
 
 #define RTPE_CONFIG_UINT64_PARAMS \
 	X(bw_limit)