Another Intel 4K + GNOME Optimization Yields 5% Faster Render Times, 10% Lower Power Use

Daniel van Vugt of Canonical who has been responsible for many GNOME performance optimizations in recent years has another tantalizing improvement under review.

Recently the Canonical developer has been working on improving the Intel graphics experience on GNOME particularly at 4K after he upgraded his display and was unimpressed by the current level of performance for this default Ubuntu desktop environment.

A few days ago he discovered GNOME's window culling was broken leading to reduced performance. That issue has already been corrected in a newer merge request and merged for the GNOME 3.37/3.38 development code as well as back-porting for the 3.36 series.

Today, Daniel is presenting what should be another significant optimization. Daniel explained in the MR, "We were setting the pipeline colour to all white (1.0, 1.0, 1.0, 1.0) and so the default layer combine function multiplied each pixel (R, G, B, A) by all ones. Obviously multiplying by one four times per pixel is a waste of effort so we remove the colour setting and set the layer combine function to a trivial shader that will ignore whatever the current pipeline colour is set to. So now we do zero multiplies per pixel."

Daniel found that avoiding the extra and unnecessary operations on a 4K display driven by Intel graphics is now leading to around 5% faster render times and 10% lower graphics power usage. This can obviously help GNOME setups with displays of all sizes, but with 4K displays given the higher pixel count will obviously mean greater savings. Virtual machines relying upon software renderers should also see beneficial improvements thanks to this change.

As of writing, this change is still under review. It will be interesting to see what more Daniel and others manage to optimize by GNOME 3.38 due out in September.