Some further notes (and experiments) on optimizations

1 files changed, 9 insertions, 4 deletions

diff --git a/libs/ardour/port_manager.cc b/libs/ardour/port_manager.cc
index 98b85e03b7..df6eee247b 100644
--- a/libs/ardour/port_manager.cc
+++ b/libs/ardour/port_manager.cc
@@ -755,7 +755,7 @@ PortManager::cycle_start (pframes_t nframes, Session* s)
 
 	/* TODO optimize
 	 *  - when speed == 1.0, the resampler copies data without processing
-	 *   it may be more efficient to just run all in sequence
+	 *   it may (or may not) be more efficient to just run all in sequence.
 	 *
 	 *  - single sequential task for 'lightweight' tasks would make sense
 	 *    (run it in parallel with 'heavy' resampling.
@@ -766,8 +766,13 @@ PortManager::cycle_start (pframes_t nframes, Session* s)
 	 *    amount of work (how many connected ports are there, how
 	 *    many resamplers need to run) vs. available CPU cores and semaphore
 	 *    synchronization overhead.
+	 *
+	 *  - input ports: it would make sense to resample each input only once
+	 *    (rather than resample into each ardour-owned input port).
+	 *    A single external source-port may be connected to many ardour
+	 *    input-ports. Currently re-sampling is per input.
 	 */
-	if (s && s->rt_tasklist () /* && fabs (Port::speed_ratio ()) != 1.0 */) {
+	if (s && s->rt_tasklist () && fabs (Port::speed_ratio ()) != 1.0) {
 		RTTaskList::TaskList tl;
 		for (Ports::iterator p = _cycle_ports->begin(); p != _cycle_ports->end(); ++p) {
 			tl.push_back (boost::bind (&Port::cycle_start, p->second, nframes));
@@ -784,7 +789,7 @@ void
 PortManager::cycle_end (pframes_t nframes, Session* s)
 {
 	// see optimzation note in ::cycle_start()
-	if (s && s->rt_tasklist () /* && fabs (Port::speed_ratio ()) != 1.0 */) {
+	if (s && s->rt_tasklist () && fabs (Port::speed_ratio ()) != 1.0) {
 		RTTaskList::TaskList tl;
 		for (Ports::iterator p = _cycle_ports->begin(); p != _cycle_ports->end(); ++p) {
 			tl.push_back (boost::bind (&Port::cycle_end, p->second, nframes));
@@ -887,7 +892,7 @@ void
 PortManager::cycle_end_fade_out (gain_t base_gain, gain_t gain_step, pframes_t nframes, Session* s)
 {
 	// see optimzation note in ::cycle_start()
-	if (s && s->rt_tasklist () /* && fabs (Port::speed_ratio ()) != 1.0 */) {
+	if (s && s->rt_tasklist () && fabs (Port::speed_ratio ()) != 1.0) {
 		RTTaskList::TaskList tl;
 		for (Ports::iterator p = _cycle_ports->begin(); p != _cycle_ports->end(); ++p) {
 			tl.push_back (boost::bind (&Port::cycle_end, p->second, nframes));