<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body text="#000000" bgcolor="#ffffff"> I'm running here into a heavy performance problem on both ATI and nVidia cards and the culprit is the glXSwapBuffers call. I've got here two performance readings showing the problem. The first reading is in a case where performance is somewhat okay. <pre>II [OpenGL] OpenGL Timer: BeginFrame: Run Optimizers = 3ys II [OpenGL] OpenGL Timer: BeginFrame: Make Current = 57ys II [OpenGL] OpenGL Timer: BeginFrame: Activate primary GC = 7ys II [OpenGL] OpenGL Timer: EndFrame: Entering = 2312ys II [OpenGL] OpenGL Timer: EndFrame: Activate primary GC = 28ys II [OpenGL] OpenGL Timer: EndFrame: Flush = 27ys II [OpenGL] OpenGL Timer: EndFrame: Swap Buffers = 4238ys II [OpenGL] OpenGL Timer-Total End Frame = 6694ys</pre> "EndFrame: Entering" is the time for all rendering for the window (hence the time between leaving BeginFrame and entering EndFrame calls). The flush there is only to make sure it is a problem with glXSwapBuffers. 4ms for a swap I would consider a bit high if the rendering itself is done in <3ms but maybe this is normal, I don't know. But when I show/hide the window to switch to another window rendering the same 3D scene (for testing purpose) and switching back (always only one of the two windows visible, aka mapped to the screen) performance breaks down horribly. <pre>II [OpenGL] OpenGL Timer: BeginFrame: Run Optimizers = 4ys II [OpenGL] OpenGL Timer: BeginFrame: Make Current = 59ys II [OpenGL] OpenGL Timer: BeginFrame: Activate primary GC = 14ys II [OpenGL] OpenGL Timer: EndFrame: Entering = 2560ys II [OpenGL] OpenGL Timer: EndFrame: Activate primary GC = 37ys II [OpenGL] OpenGL Timer: EndFrame: Flush = 45ys II [OpenGL] OpenGL Timer: EndFrame: Swap Buffers = 66642ys II [OpenGL] OpenGL Timer-Total End Frame = 69401ys</pre> As it is visible here swap buffers eats suddenly 66ms! This is on the ATI system. On the nVidia system there is no difference between the two situations but swap buffer always consumes 48ms. Any ideas what can cause glXSwapBuffer to horribly slow down like this? The DE is KDE4 with compositing present but disabled (so it should not have any influence). I read somewhere that somebody tried placing glXSwapBuffers in a separate thread. Would this not cause troubles with the X-server? (meaning, is X thread safe?). But even if this would work 68ms for a swap is brutal. x11-base/xorg-server: 1.8.2 x11-drivers/ati-drivers: 10.9-r1 <div class="moz-signature">-- Mit freundlichen Grüssen Plüss Roland Leader und Head Programmer - Game: Epsylon ( <a class="moz-txt-link-freetext" href="http://www.indiedb.com/games/epsylon">http://www.indiedb.com/games/epsylon</a> , <a class="moz-txt-link-freetext" href="http://epsylon.rptd.ch">http://epsylon.rptd.ch</a> ) - Game Engine: Drag[en]gine ( <a class="moz-txt-link-freetext" href="http://www.indiedb.com/engines/dragengine">http://www.indiedb.com/engines/dragengine</a> , <a class="moz-txt-link-freetext" href="http://dragengine.rptd.ch">http://dragengine.rptd.ch</a> ) - Normal Map Generator: DENormGen ( <a class="moz-txt-link-freetext" href="http://epsylon.rptd.ch/denormgen.php">http://epsylon.rptd.ch/denormgen.php</a> ) and others </div> </body> </html>