Comment 290 for bug 252094

Richard, yes those bar charts indicate there is performance regressions, but that's nothing we don't already know. Unfortunately the author didn't gather Xorg.0.log, glxinfo, xdpyinfo, or other data which could help in investigating the problem.

For those of you looking at glxgears fps, you're going to get a rude shock pretty soon. You've heard that glxgears is not a benchmark. It measures the blitting speed of writing a pixmap to the graphics buffer. Well, video monitors display that data at a limited rate (your refresh rate in fact). Most monitors display at a rate of 60-100 Hz (essentially 60-100 fps). So when you see glxgears saying it is writing frames at 800 FPS, well probably 700 of those frames never even get to the monitor, and thus are just a waste of electricity. Cleverly, upstream is now synchronizing the blitting speed to the monitor's refresh rate, so that it writes only as fast as the monitor can display. So you should see your glxgears FPS values drop down to something nearly equaling your monitor refresh rate. ;-)