Comment by meheleventyone
4 years ago
It's pretty straightforward case of prioritization. There are always more things to do on a game project than you have people and time to do.
The game runs well enough so the people who could optimize things by rewriting them from CPU to GPU are doing other things instead. Later performance is a noticeable problem to the dev team, from customer feedback and need to ship in more resource constrained environments (VR and XBox) and that person then can do work to improve performance.
It's also handy to have a reference CPU implementation both to get your head around a problem and because debugging on the GPU is extremely painful.
To go further down the rabbit hole it could be that they were resource constrained on the GPU and couldn't shift work there until other optimizations had been made. And so on with dependencies to getting a piece of work done on a complex project.
Makes sense and then it kinda agrees with parent comment that "Microsoft developers simply didn't have performance in the vocabulary".
Yes, there is no doubt that "there are always more things to do on a game project than you have people and time to do". However how there is time to firstly make "main thread on single core" monster and then redo it according to game development 101 - make use of GPU.
It is no joke - GPU was barely loaded, while CPU choking. On a modern game released by top software company proudly presenting their branding in the very title.
> However how there is time to firstly make "main thread on single core" monster and then redo it according to game development 101 - make use of GPU.
The single threaded code was taken from Microsoft Flight Simulator X, the previous version of this game from 2006. It was not done from scratch for the new game, and it still hasn't been replaced. They've just optimized parts of it now.
Another important performance bottleneck is due to the fact that the game's UI is basically Electron. That's right, they're running a full blown browser on top of the rest of the graphis for the UI. Browsers are notoriusly slow because they support a million edge cases that aren't always needed in a game UI.
For anyone interested in learning more about Microsoft Flight Simulator 2020 optimizations I can recommend checking out the Digital Foundry interview with the game's technical director. https://www.youtube.com/watch?v=32abllGf77g
It was actually made by a third-party game development studio rather than Microsoft.
Also the assumption that the culture of the Windows Terminal team is the same as the team building a flight simulator is a bit far fetched. Large organisations typically have very specific local cultures.
Rewriting stuff from CPU to GPU also isn't 101 game development. Both because it's actually quite hard and because not all problems are amenable to GPU compute and would actually slow things down.
I work within game development. Mainly on graphics programming and performance. There's always a number of things I know would speed various systems up but that I don't have time to implement because there are so many bigger fires to put out.
Also, I have rewritten CPU implementations to run on the GPU before and it's often nontrivial. Sometimes even in seemingly straightforward cases. The architectures are very different, you only gain speed if you can properly parallelize the computations, and a lot of things which are trivial on the CPU becomes a real hassle on the GPU.