MAINT-3131 Attempt to work around drivers that lack timer query and ignore glFinish calls.

1 files changed, 22 insertions, 2 deletions

diff --git a/indra/newview/llglsandbox.cpp b/indra/newview/llglsandbox.cpp
index f620bf19fb..0a423e6785 100755
--- a/indra/newview/llglsandbox.cpp
+++ b/indra/newview/llglsandbox.cpp
@@ -969,6 +969,8 @@ F32 gpu_benchmark()
 	//wait for any previoius GL commands to finish
 	glFinish();
 	
+	bool busted_finish = false;
+
 	for (S32 c = -1; c < samples; ++c)
 	{
 		LLTimer timer;
@@ -983,7 +985,18 @@ F32 gpu_benchmark()
 		}
 		
 		//wait for current batch of copies to finish
-		glFinish();
+		if (busted_finish)
+		{
+			//read a pixel off the last target since some drivers seem to ignore glFinish
+			dest[count-1].bindTarget();
+			U32 pixel = 0;
+			glReadPixels(0,0,1,1,GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
+			dest[count-1].flush();
+		}
+		else
+		{
+			glFinish();
+		}
 
 		F32 time = timer.getElapsedTimeF32();
 
@@ -994,7 +1007,14 @@ F32 gpu_benchmark()
 
 			F32 gbps = gb/time;
 
-			results.push_back(gbps);
+			if (!gGLManager.mHasTimerQuery && !busted_finish && gbps > 128.f)
+			{ //unrealistically high bandwidth for a card without timer queries, glFinish is probably ignored
+				busted_finish = true;
+			}
+			else
+			{
+				results.push_back(gbps);
+			}		
 		}
 	}