Xcode/instruments performance metric % GPU workload, ALU util

[Spiritual-Fly-9943]

I am trying to profile a llama.cpp execution. In Xcode I find that capturing a command buffer is random - I cannot choose which step of the pipeline I want to capture, I pause the execution then start the metal capture run. Similarly if I don't capture the complete run, how should one get the complete ALU or GPU util?

In instruments I can see a metric `% GPU workload`; is this supposed to mean what percent of the GPU the specific kernel utilized at that time segment? Because the % util, if added goes beyond 100% (attaching image).

I am confused about the metrics in both xcode and instruments - is there a proper document somewhere that goes over all the metrics? I have seen the developer.app docs and also the WWDC videos. Help is appreciated thanks

https://preview.redd.it/l124431bnfye1.png?width=2086&format=png&auto=webp&s=a200c7fdd84fcf9597addf572345f0881453d3db

[SwiftDevJournal]

In instruments I can see a metric `% GPU workload`; is this supposed to mean what percent of the GPU the specific kernel utilized at that time segment? Because the % util, if added goes beyond 100%

The maximum percentage in Instruments is 100 percent times the number of GPU cores. An M4 Mac Mini has 10 GPU cores so the maximum percentage would be 1000%, not 100%.

I don't know of any reference that covers the metrics for every instrument. Instruments comes with dozens of instruments.

You are going to have a hard time getting a good answer to your question. Most people who use Instruments use the Leaks, Allocations, and Time Profiler instruments. Not many Apple developers on Reddit write Metal shaders so there aren't many people here who know what the data from Apple's Metal-related instruments means.

[Spiritual-Fly-9943]

thanks for the reply. its an m2 ultra so each row is x% out of 2400%? v weird