topic Re: μarch bottom up tab has a bad speculation metric that does not match event or summary views in Analyzers

μarch bottom up tab has a bad speculation metric that does not match event or summary views

TyL8 — Sun, 22 Dec 2024 16:42:31 GMT

I believe this question has been asked before, but the OP no longer responded:

https://community.intel.com/t5/Analyzers/Weird-result-when-testing-Cinebench2024-and-COMSOL/m-p/1522184/thread-id/23870

I am trying to profile PCSX2, a PlayStation 2 emulator. I'm finding that some functions have moderate to high levels of bad speculation due to "Machine Clears."

The summary of my sample shows 0.0% machine clears:

More interestingly, I'm reading that there should be three related events

MACHINE_CLEARS.COUNT

MACHINE_CLEARS.MEMORY_ORDERING

MACHINE_CLEARS.SMC

I can only find MACHINE_CLEARS.COUNT in the event view and as seen below when sorting by descending order there are a total of 0 machine clears during my entire sample.

I have tried the full finalization mode and have invoked VTune finalization from the command line with AMPLXE_SAMPLES_TO_LOAD=0 with no success.

Attached is my entire sample folder zipped.

I would like to know if the machine clears are actually happening, or if I should consider the machine clear metric in the bottom up view to be incorrect.

Note: A reproducible executable might will be difficult to produce, but it's not impossible.

Thanks,
Ty Lamontagne

Re: μarch bottom up tab has a bad speculation metric that does not match event or summary views

yuzhang3_intel — Tue, 24 Dec 2024 00:36:47 GMT

I am not sure if it is one bug, the platform is too old. But you can customize the uarch-exploration and add the other two related machine clear events for monitoring, try again.

Re: μarch bottom up tab has a bad speculation metric that does not match event or summary views

TyL8 — Thu, 26 Dec 2024 16:47:59 GMT

Thanks, I totally forgot that you can create your own analysis.

Good news, after enabling those events, and bringing the "Sample After" number way down, I can see the cause of the machine clears.

Thanks!