Taking Flow for a spin on the Raspberry Pi 400

For me, one of the technology highlights of 2020 was the release of the Raspberry Pi 400. Its performance is very similar to high end set-top boxes and streaming media players. As the Raspberry Pi OS also includes an up to date Chromium browser, I was very keen to do some head-to-head performance comparisons with Flow.

I was really pleased with Flow’s performance on some of the benchmarks I tried. MotionMark, one of the benchmarks we regularly use, showed Flow to be over six times faster than Chromium. However, when I replaced my TV (720p) with an HD monitor (1080p), the margin on some was lower than I’d expected. Our engineers found the cause, but it took me a few minutes to get my head around what they were saying…

The Raspberry Pi 400 has an inbuilt algorithm which can slow down both the CPU and GPU to save power. It monitors the load on the CPU which, for many applications, is a good enough indicator. But for Flow, this doesn’t always hold. Unlike Chromium, Flow’s CPU load is often very small during heavy animation as all the drawing work is being done directly by the GPU. With the Particle Acceleration benchmark for instance, the Pi 400’s power management algorithm was wrongly assuming there was little to do and therefore starving the GPU. 

This algorithm can be disabled to keep the CPU running at full speed all the time. Making this change can improve the performance of both Flow and Chromium. The improvement for Flow is larger than that for Chromium whose load appears to be more CPU heavy. For Flow, the performance gain on the Particle Acceleration benchmark was the most impressive: at HD resolution, Flow ran at 56 fps compared with just 26 fps previously. Chromium ran at 15 fps in both cases.

As an embedded browser Flow is already very capable, but as a desktop browser it’s still a work in progress. There are a few things that don’t work on the Raspberry Pi 400 just yet, like video. There’s also no toolbar so it doesn’t feel like a desktop browser, but even with these restrictions it’s a good basis for an embedded browser evaluation. As we continue to improve Flow, we will update the Raspberry Pi preview so anyone interested can now see the progress for themselves.

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