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Comment by slowmovintarget | Hacker News Reader

I recall Jonathan Blow talking about how it's basically impossible to eliminate stutter on Windows now due to a number of design decisions in the OS driver system itself.

I'm wondering if this is the moment for Linux gaming. Valve has certainly taken it a long ways from where it was.

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Linux has the same issue in principle, the problem is that shaders must be compiled anew for each driver version, at runtime. It is impractical for the developer, but a distributor like Steam can actually track and redistribute caches for most combinations of drivers and GPUs in active use. Also, warming up the cache (not just precompiling) is possible.

Steam is always compiling shaders before starting a game.

What is this needed for actually, can't these come precompiled with the game, just like the game's executable?

There are 3 brands of GPU so max 3 precompiled versions needed? Is that naive to assume this? CPU's need only one version mostly between AMD and Intel (or at most a few for different SIMD instructions)

Unlike low level SIMD instructions, GPUs work on higher level APIs: Vulkan, DirectX, OpenGL. How that gets interpreted by the GPU changes with driver updates. That's how Intel Arc GPU performance started off in a somewhat bad state yet are steadily improving. Changes in interpretation also mean changes in shaders, so you can't just take shaders on one version of a driver and use it on another.

Internal pipelines can vary between GPU architecture too. Currently AMD ships a different branch of their own Windows drivers for the new RDNA3 architecture GPUs (RX 7000 series). So precompiled shaders probably work won't between architectures.

But why do they change this per driver update? That sounds horrible to do!

CPU's are not changing their instructions based on driver updates either.

IMHO, time for CPU's to offer thousands-of-floats-wide SIMD instruction sets instead of the measily 512 bits, that can do the same as GPU's but are way more stable, and get rid of those annoying, version-of-driver-dependent, install-100-python-libraries-to-use-them GPU's.

Performance. Vendors will literally go in and hack the shaders for major titles. Also, drivers have bugs.

GPUs will never be outperformed by a CPU with wider SIMD. Intel learned that the hard way with Larrabee. They are on a different place on the pareto front.

Performance at the cost of stutter. So not really performance...

When did compiling of shaders become a thing? Nvidia GeForce had shaders in the year 2001 but I don't remember ever seeing this then. The first time I saw compiling of shaders happen was in 2017 in a console emulator I think.

So how did it work before then, and what exactly has this compiling now improved compared to before?

It only stutters the first time the shader is used, but modern games use a lot of shaders and they are more complex. In modern APIs it is not just shaders but a combination of shaders and state.

They can be precompiled, but not to the point where there is no stutter, because some optimizations only happen at the point where the shader is executed. That is why you need a warmup. You need to actually execute the shader. Theoretically with Vk/D3D12 you can cache and ship the entire state, but again, it is a combinatorial explosion of drivers and devices.

I think it’s not the moment for Linux gaming in general, but more so the moment for certain devices like the Steam Deck. Fixed hardware platform is what you need to precompile shaders and eliminate stutter. I would love for Valve to put out a box that sits under your TV with an APU on par with the PS5

Mesa (the Linux OpenGL driver) supports caching shaders on any GPU. And Vulkan essentially has shader caching built in at the specification level. I know that Steam ships precompiled Vulkan shaders, and while there's no equivalent for Mesa's shader cache yet, it shouldn't be a huge issue since it would only cause a short delay the first time the shader is loaded.

Playing Cyberpunk 2077 in Linux on Steam Proton currently. I've not seen any stutter whatsoever. I frame limit it to 60fps and it never dips below that, with most settings on the highest (though ray tracing is grayed out in settings despite supported Nvidia card so that's disabled).

Linux has noticeably worse framepacing than Windows ime

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