From: Robin Gareus <robin@gareus.org>
Date: Tue, 18 Dec 2018 12:30:31 +0000 (+0100)
Subject: Add LV2 option/extension for plugin thread sched priority
X-Git-Url: https://main.carlh.net/gitweb/?p=ardour.git;a=commitdiff_plain;h=0a3fc4a87fcdab7f7c1ed95d42ec7ac28c95c3e1

Add LV2 option/extension for plugin thread sched priority

This allows plugins that need threads to process to configure their
thread priority to not interfere with the host's process threads.
---

diff --git a/libs/ardour/lv2_plugin.cc b/libs/ardour/lv2_plugin.cc
index 79bef11cdd..15c96ac83e 100644
--- a/libs/ardour/lv2_plugin.cc
+++ b/libs/ardour/lv2_plugin.cc
@@ -37,6 +37,7 @@
 #include "pbd/compose.h"
 #include "pbd/error.h"
 #include "pbd/locale_guard.h"
+#include "pbd/pthread_utils.h"
 #include "pbd/replace_all.h"
 #include "pbd/xml++.h"
 
@@ -495,6 +496,8 @@ LV2Plugin::init(const void* c_plugin, samplecnt_t rate)
 	LV2_URID atom_Int = _uri_map.uri_to_id(LV2_ATOM__Int);
 	static const int32_t _min_block_length = 1;   // may happen during split-cycles
 	static const int32_t _max_block_length = 8192; // max possible (with all engines and during export)
+	static const int32_t rt_policy = PBD_SCHED_FIFO;
+	static const int32_t rt_priority = pbd_absolute_rt_priority (PBD_SCHED_FIFO, AudioEngine::instance()->client_real_time_priority () - 2);
 	/* Consider updating max-block-size whenever the buffersize changes.
 	 * It requires re-instantiating the plugin (which is a non-realtime operation),
 	 * so it should be done lightly and only for plugins that require it.
@@ -511,6 +514,10 @@ LV2Plugin::init(const void* c_plugin, samplecnt_t rate)
 		  sizeof(int32_t), atom_Int, &_seq_size },
 		{ LV2_OPTIONS_INSTANCE, 0, _uri_map.uri_to_id("http://lv2plug.in/ns/ext/buf-size#nominalBlockLength"),
 		  sizeof(int32_t), atom_Int, &_impl->block_length },
+		{ LV2_OPTIONS_INSTANCE, 0, _uri_map.uri_to_id("http://ardour.org/lv2/threads/#schedPolicy"),
+		  sizeof(int32_t), atom_Int, &rt_policy },
+		{ LV2_OPTIONS_INSTANCE, 0, _uri_map.uri_to_id("http://ardour.org/lv2/threads/#schedPriority"),
+		  sizeof(int32_t), atom_Int, &rt_priority },
 		{ LV2_OPTIONS_INSTANCE, 0, 0, 0, 0, NULL }
 	};