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SMI problem on AMD Epyc 7301

Question asked by f.popchenko on Jun 3, 2019

Hello!

I'm working with AMD Epyc 7301 (AMD64 Family 17h model 00h-0Fh) with QNX (real-time OS) and have SMI interruptions on all CPUs every 32 ms for ~400 us. But in Linux (SLES RT) i dont't see such behaviour and the SMI counter in MSR results 0. I've read Performance Tuning Guidelines for Low Latency Response on AMD EPYC™-Based Servers Application Note and perform all BIOS optimization to decrease or remove SMIs, but it didn't work in this case. 

So, I have some questions:

1. Is there a way to disable SMI or sources of SMI in MSR or other specific registers, that I can write from OS?

2. Do you have any suggestions what can be a reason for such behaviour?

3. In case if you known with this promlem, what should I do to reduse SMIs in QNX like it works in Linux?

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