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    Low CPU Performance on AMD 3960X

    Scheduled Pinned Locked Moved Compute
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    • G Offline
      gabm
      last edited by gabm

      I have a system with a AMD Threadripper 3960X and the CPU performance on xcp-ng 8.1.0 seems to be very low. Has this kind of system been used successfully before?

      Here is how I come to this conclusion: I have an older XenServer-based machine with an Intel 6770HQ CPU and the computation tasks that run in the VMs are about 30% faster than on the new system after migration.

      So I dug a bit into it and ran a very simple benchmark in the guests and dom0: time $(i=0; while (( i < 999999 )); do (( i ++ )); done). On the old Intel machine this takes about 4s, on the new AMD machine almost 10s.

      Any ideas on what to do?

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      • olivierlambertO Offline
        olivierlambert Vates 🪐 Co-Founder CEO
        last edited by

        Might be a CPU power setting/governor. Check your BIOS settings.

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        • G Offline
          gabm
          last edited by gabm

          It looks like.

          Unfortunately there is no easy "Power mode" or "Performance mode" setting on our asrock trx40. But we managed to set the default frequency of the CPU to its max frequency and that solved the problem for now. We now get similar performance indicators as on the old intel CPU and as indicated in the IRC.

          When xcp-ng boots up, we see some ACPI error messages, maybe thats related?

          https://ibb.co/bgXW9Tv

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          • olivierlambertO Offline
            olivierlambert Vates 🪐 Co-Founder CEO
            last edited by

            Buggy ACPI tables is sadly more common on non-enterprise grade hardware 😞

            Might be related or not, but thanks for the feedback about frequency 🙂

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