Took more than 10minutes to create compute pipeline on Linux

[GopherJ]

Description creating compute pipeline becomes super slow once some changes have been made to the shader

Repro steps Ideally, a runnable example we can check out. Expected vs observed behavior faster

Extra materials N/A

Platform Linux Mint based on ubuntu 22.04, i7-13gen, 64GB, GTX4090

[ErichDonGubler]

@GopherJ: This issue does not actually provide instructions for running an example of the behavior described. I don't think it's reasonable to expect contributors here to build and run binaries that are not trivial to validate for safety and security without instructions, so: Unless you can make your example small (i.e., everything in a pair of Cargo.toml and main.rs), determine what changes specifically are causing this behavior (perhaps as a diff), and quantify what "slow" means, I intend to close this issue.

[GopherJ]

hi @ErichDonGubler it's more a problem of running wgpu on linux. If more context is needed I can try to make one later.

And it's not related to my code because the bottle neck is on create_compute_pipeline API

[Wumpf]

our ci regularly runs create_compute_pipeline with various inputs on all platforms without this issue, so it clearly is related to either the sample at hand or your setup. So yes, more context is needed!

[GopherJ]

I'll try to provide a reproducible example later.

[cwfitzgerald]

It would be useful to know the timing of the underlying vkCreateComputePipelines call is taking, as I suspect that the hang is entirely within that call.

[GopherJ]

https://github.com/GopherJ/webgpu-shaders

@ErichDonGubler @cwfitzgerald here the reproduce repro

if you try to run:

cargo test --release --no-default-features --features std -- --test-threads 1 --nocapture

it basically hangs for a while to compile OR create compute pipeline, on macos I don't observe, things are super fast

Environment:

[GopherJ]

any idea?

[ErichDonGubler]

I don't have a Linux environment handy at the moment, so I can't directly contribute debugging hre. Inspecting the reproducible example repro, however, I suspect there is still some work to do to make the example smaller:

1. If the issue is creating a compute pipeline, not executing one, we shouldn't need to keep any of the code past the stage of creating a compute pipeline. Things like constructing and executing compute passes should be unnecessary.
2. I see multiple compute pipelines being created, but this bug has only mentioned a specific pipeline being slow. We should be able to limit the reproducible example to code that creates only that pipeline.
3. Your cargo test reproduction steps don't note which #[test] entries are slow. Is it all of them? Only some of them? We should narrow the reproduction steps down to only one of these cases, if possible.

[jimblandy]

The Mozilla folks aren't going to be prioritizing this for the moment. As always, others are welcome to investigate.