From 137b596943a9a1ef853da7a3ba444adee48e2d68 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Tue, 15 Nov 2016 11:01:41 +0000
Subject: [PATCH] Enabled sharing of main threads processor affinity to the
 next required thread for CullDrawThreadPerCamera and
 CullThreadPerCameraDrawThreadPerContext

---
 src/osgViewer/ViewerBase.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/osgViewer/ViewerBase.cpp b/src/osgViewer/ViewerBase.cpp
index 510ab3adb..508889188 100644
--- a/src/osgViewer/ViewerBase.cpp
+++ b/src/osgViewer/ViewerBase.cpp
@@ -113,6 +113,13 @@ void ViewerBase::configureAffinity()
     bool requiresCameraThreads = false;
     bool requiresDrawThreads = false;
 
+    unsigned int availableProcessor = 0;
+
+    // set affinity for first processor
+    _affinity = OpenThreads::Affinity(availableProcessors[availableProcessor]);
+
+    // all threading models except DrawThreadPerContext can share the first cull or culldraw threads with thread with the main thread,
+    // so only increment the availableProcessor for DrawThreadPerContext to prevent draw threads sitting on the same thread as main thread that does cull
     switch(_threadingModel)
     {
         case(CullDrawThreadPerContext):
@@ -121,6 +128,7 @@ void ViewerBase::configureAffinity()
 
         case(DrawThreadPerContext):
             requiresDrawThreads = true;
+            ++availableProcessor;
             break;
 
         case(CullThreadPerCameraDrawThreadPerContext):
@@ -133,9 +141,7 @@ void ViewerBase::configureAffinity()
     };
 
 
-    unsigned int availableProcessor = 0;
 
-    _affinity = OpenThreads::Affinity(availableProcessors[availableProcessor++]);
 
     if (requiresCameraThreads)
     {