Performance on “secondary” GPUs has historically been suboptimal on Linux, especially with external GPUs. Let’s take a look at why it’s slow, and how we’re finally fixing it. How Multi-GPU even works To know how things work with multiple GP…
This year, there was another display next hackfest, this time in Nice, France. This was a very productive hackfest, so I’ll focus just on my personal highlights here. As mentioned in the blog post about the last hackfest, the current backli…
While most new applications use the GPU for rendering to achieve better performance and battery life, there are some new applications and a lot of older applications that still use CPU rendering. More specifically relevant for KDE, while Qt…
As an exception to my usual posts, this time I’ll write about a feature that’s already released. Since Plasma 6.6, you can enable automatic brightness in the display settings… let’s take a look at how it works, and why it took so long to ma…
In preparation for, and at the 2025 display next hackfest, I did a bunch of hacking on using more driver features for improved efficiency and performance. Since then, I polished up the results a lot more, held a talk about this at XDC 2025
This year there was another “Display Next Hackfest”, this time thanks to AMD organizing and hosting the event at their office in Markham, Toronto. Just like the last hackfests, there were other compositor developers and driver developers pr…
Many people are, understandably, confused about brightness levels in content creation and consumption - both for SDR and for HDR content. Even people that do content creation as their job sometimes get it really wrong. Before jumping into t…
Most operating systems nowadays provide a feature like night light: Colors are adjusted over the course of the day to remove blue light in the evening, to potentially help you sleep1 and make your eyes more comfortable. Linux is no differen…
This one required a few other features to be implemented first, so let’s jump right in. A big part of what a desktop compositor needs to get right with HDR content is to show SDR and HDR content properly side by side. KWin 6.0 added an SDR
In Plasma 6.2, KWin switched from doing linear blending with HDR to blending in a gamma 2.2 space. Let’s take a look at what that means, and why it was done. When KWin composites, it paints window by window, going by the order of how the wi…
Fractional scaling is hard. Anyone that had the misfortune of working on it knows that… so it won’t surprise a lot of people that it’s not all figured out yet! Today I’ll talk about the fractional scaling problems with KWin’s server side de…
Profiling displays is already not a super simple thing on its own, but things get more complicated when you try to profile your display in Wayland - profiling applications don’t support Wayland yet, some APIs on the compositor side to make