The Latest GNOME Performance Issue Being Addressed Are OpenGL Pipeline Stalls
Van Vugt continues working on some terrific upstream contributions to GNOME for improving the default desktop of Ubuntu. As is the case with most of his GNOME work, it's in the area of bettering the performance by often addressing various long-standing bugs. On top of his other fixes so far for GNOME 3.34, he has been investigating OpenGL pipeline stalls most recently. These OpenGL pipeline stalls lead to frame skips and limiting the frame-rate when such situations occur.
He has discovered GL pipeline stalls within glReadPixels during cursor movements or animations under the cursor. For the NVIDIA driver stack on X.Org, he discovered stalls happening with every frame during calls to glFinish.
Those stalls are what he's encountered so far. Fortunately, his other work being done on geometric picking and dropping the threaded swap-wait for the NVIDIA driver should help in this area.
OpenGL pipeline stalls typically happen when stuck waiting on the client for more rendering commands/data / waiting on the CPU or having to stop the rendering process in order to read back / deal with other data.
Here's to hoping he will be able to uncover more performance fixes in time for GNOME 3.34 and in turn improving Ubuntu 19.10.
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