Hacker News new | ask | show | jobs
by customkitchen 1373 days ago
That flag has been broken for years: https://bugreports.qt.io/browse/QTBUG-70387

I doubt it will ever be fixed, because it offers no benefits when the application itself uses actual hardware rendering with GL or Vulkan. XCB can't speed that up at all.
1 comments
jcelerier 1373 days ago
...? the bugreport you pasted seem to have been fixed and merged 3 years ago.

The vast, vast, vast majority of the apps i use daily don't do any GPU rendering, just plain classic widget-based productivity apps

link
customkitchen 1373 days ago
Sorry, I didn't clarify. The bug was fixed with some use of pixmaps, in other situations it's still broken.

It sounds like the vast majority of apps you use are very old. Even plain productivity apps benefit from GPU rendering. If they don't it's because those apps are far behind, compare to things like Electron apps where everything has been GPU accelerated for quite some time because of Skia.

link
jcelerier 1373 days ago
I find electron apps absolutely horrendous to use. The apps I use most are Zim, QtCreator, Strawberry, and the KDE apps: Okular, etc. - most of the time when I remote ssh it's for pavucontrol-qt, dolphin (the file manager) or mainly the app I develop, https://ossia.io (for instance for working on a show that is taking place over a raspberry pi). None of those force any kind of GPU rendering.

Also apps that do gpu rendering make my laptop really heat up and loose battery quickly compared to when it's not in use - I don't use a compositor partly for this (+ the occasional frame lag)

link
customkitchen 1373 days ago
That's not really relevant. You can personally choose to not use Electron apps, but many people cannot or do not want to choose to do that. Like it or not, it's a thing now. I've noticed a lot of developers seem to have this confusion that anyone else can avoid Electron. I guess you can if you spend all day in the terminal and the IDE but most other people cannot.

And that sounds like something is seriously wrong with your machine or your drivers. GPU rendering has massively improved performance and battery life on every machine I've ever tried. And especially on embedded devices with a low power mobile GPU, see for example here: https://social.librem.one/@dos/104984930233748319

Compositing should do so as well by avoiding unnecessary redraws. That sequencer would probably benefit greatly on a Raspberry by using GPU rendering, the screenshot even shows it rendering video and shaders...

link
jcelerier 1372 days ago
> Compositing should do so as well by avoiding unnecessary redraws.

I use a tiling WM so I doubt it would help much. If anything, if I run a whole system profile with perf, rendering does not even show up when compared to just running a git status here.

> That sequencer would probably benefit greatly on a Raspberry by using GPU rendering, the screenshot even shows it rendering video and shaders...

Sure, the video & shader parts use GPU of course. But for the main GUI, it can be rendered with OpenGL or with Qt's software renderer ; from my tests (and lord knows I've spent entire weeks profiling and doing everything I could to improve rendering performance) the OpenGL backend for the main GUI only becomes more worth it when using a 4k resolution - and GL is absolutely full of bugs on e.g. windows ; yes there are still people with GMA500 GPUs. Qt's software renderer has no issue rendering at a 1080 screen size on a Pi 3.

link