Tokamak 6 Kicking Off: Why switch graphics stacks?

We (the KDE Plasma Team) are sitting at the SUSE office in N├╝rnberg, Germany right now, kicking off the already 6th edition of Tokamak, which is the name for (most of) our Plasma meetings. A Tokamak is a container for Plasma, which uses magnetic force to keep the Plasma in one (very hot) place. For the Plasma team, it provides a high-bandwidth setting where we can discuss, design, review and hack on the technology behind the Plasma workspaces. This meeting’s topic is Plasma2, the evolution of Plasma into the Qt5 and Wayland world.

First, we agreed on a bottom line: “Plasma 2 will be at least as good as the current Plasma, and probably better in many aspects.” This means that we’ll have to invest considerable effort and time into stabilization. At this point, where we are probably still a year or so away from a Plasma2-based release, making it part of our planning now will allow us to focus on the things that we think, matter. Among that is making sure the transition to KDE Frameworks 5, Plasma 2 and Wayland will be as seamless as possible, and perceived as an upgrade to our users.

But why are we doing this? Why are we putting so much work into it, what’s the benefit for the user?

Why switch graphics stacks?

In the past years, the landscape of graphics under Linux has changed quite a bit. Many things, like memory management of the graphics stack, rendering of primitives, font rendering, and a few other things involved in the process of “getting pixels onto your screen” have changed, and they’ve changed for the better. With a stack based on Wayland (and in extension Qt5), we are able to utilise modern graphics hardware better, to reduce maintainance effort and hopefully grow the community around the graphics stack, and not at least, to make sure that every frame that ends up on the screen is perfect. In the X11 world, we can’t really control it, since we have no idea when something is painted, in which way it is, where it’s painted, and when the pixels end up on the screen. With Wayland, this process of event processing, rendering and blitting is structured and guaranteed to happen in a certain order. In the end, this transition will enable us to put 60 perfect frames every second on the screen.
The new architecture also allows us to split the rendering into its own thread, so data processing or event handling in the application doesn’t end up delaying rendering. 60 frames per second will make the UI feel smooth as buttery silk, leading to less strain on the eyes and a nicer user experience.