Comment by archi42

13 hours ago

What surprises me is the 24 GB of DDR4 DRAM on a dual channel memory controller? AFAIK there are only 8 GB or 16 GB modules, no 12 GB modules. At least I can only find 12 GB DDR5 modules listed, but not DDR4.

This means: The system likely uses 3x 8 GB modules. As a result, one channel has two modules with 16 GB total, while the other channel has only a single 8 GB module.

Not sure how big this impact is with the given memory access patterns and assuming [mostly] exclusive single-threaded access. It's just something I noted, and could be a source of unexpected artifacts.

4 comments

archi42

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sestep  8 hours ago

Yes, sorry for not being more explicit! It's 3x8GiB. Originally 4x, but one of my RAM sticks broke and I never bothered to replace it.

  • archi42  3 hours ago

    I'm not deep into the details of the AMD DRAM controller, but this detail could cause some of your anomalies. If this was an academic paper, the findings would be borderline invalid. You might want to remove the extra module and run the benchmarks again.

    At least once the tests become big enough to have some data in both partitions, the bandwidth will start to matter.

    • sestep  2 hours ago

      Thanks, I may try that.

      Out of curiosity, what do you see when running the same code on your machine?