Mastodawn

Brandon Jones Mar 11, 2025

I've written a brief guide for profiling WebGPU commands with Xcode's Metal debugger. It's... not exactly easy, but it works! I've got several ideas for how to improve it in the future, too.

Also, if you know Xcode better than me (a very VERY low bar) then I'd be thrilled if you have any suggestions to make this process better!

https://toji.dev/webgpu-profiling/xcode

Profiling WebGPU with Xcode’s Metal Debugger

Brandon Jones - Graphics and XR on the web

Toji.dev

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cassie Mar 11, 2025

@tojiro If you have control over the application you want to capture, it’s nice to explicitly instrument it with MTLCaptureManager with a file output so you can capture traces during normal execution and open the capture files afterwards. I set up one of my graphics apps so when you launch it in debug mode, it adds a menu item “capture frame” which will save a frame capture to the downloads folder so I don’t have to fiddle with attaching a debugger.

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Brandon Jones Mar 11, 2025

@porglezomp Yeah, I'm investigating exactly that now. Want to see if there's some reasonable common ground with Metal/RenderDoc/PIX so that we can set up some developer-only utils to easily spit out a capture file wherever.

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stephan

@tojiro @porglezomp
Thanks for the blog post! Was quite helpful for my endeavors to figure out how to capture WebGL2 workloads using Metal frame debugger through ANGLE. There is already some MTLCaptureManager support built-in and it’s relatively easy to patch ANGLE for Chrome Canary. But chrome GPU crashes right after a capture leading to empty or incomplete gputrace data.