Currently GPUPerfStudio does not support PerfMarkers in OpenGL, although it is on our list of desired features. One possible alternative is to use the version of gDEBugger from http://www.gremedy.com/download.php and to use the GL_GREMEDY_string_marker extension (http://www.opengl.org/registry/specs/GREMEDY/string_marker.txt) to mark your code.
Best of luck to you,
Thanks Peter. I'd been delaying using gDEBugger until I really needed to, as I don't want to waste the free trial over some trivial matter. Not sure this is important enough
Interesting that the extension exists, but it doesn't go far enough for my liking - it only allows for instantaneous markers as with D3DPERF_SetMarker. For me a structured view is key to understanding a frame.