[boywitharupee]

can someone explain how is profiling tools like this written for GPU applications? wouldn't you need access to internal runtime api?

for ex. Apple wraps Metal buffers as "Debug" buffers to record allocations/deallocations.

[MindSpunk]

Some graphics APIs support commands that tell the GPU to record a timestamp when it gets to processing the command. This is oversimplified, but is essentially what you ask the GPU to do. There’s lots of gotchas in hardware that makes this more difficult in practice as a GPU won’t always execute and complete work exactly as you specify at the API level if it’s safe to. And the timestamp domain isn’t always the same as the CPU.

But in principle it’s not that different to how you just grab timestamps on the CPU. On Vulkan the API used is called “timestamp queries”

It’s quite tricky on tiled renderers like Arm/Qualcomm/Apple as they can’t provide meaningful timestamps at much tighter granularity than a whole renderpass. I believe Metal only allows you to query timestamps at the encoder level, which roughly maps to a render pass in Vulkan (at the hardware level anyway)

[ossobuco]

I don't know about Tracy, but I've seen a couple WebGPU JS debugging tools simply intercepting calls to the various WebGPU functions like writeBuffer, draw, etc, by modifying the prototypes of Device, Queue and so on[0].

- 0: https://github.com/brendan-duncan/webgpu_inspector/blob/main...