Memory Bandwidth - default scan how does it work?

jwarner's Avatar

jwarner

07 Jun, 2018 03:23 PM

Is there any documentation on how the Memory Bandwidth tests are run, or why if I use the --memory-bandwith option runs different? I happened across this on accident why trying to figure out automating the run, and looking at some results that seemed kind of odd from a older system I have that I was running Geekbench on.

The reason I ask is that on a system that I have been running on depending on the number of threads I have selected in the command line I have found a swing of memory bandwidth for the multi-core, single core results come back with pretty much the same score every time.

If I use the GUI on the Geekbench4 and run the x64 architecture CPU test and open the task manager I can see all 56 cores being used on the system during the multi-core test. If I use the console with the --memory-workers 56 Memory bandwidth increases, memory latency slows as expected .

GUI:
Memory copy 24.4 GB sec
Memory Latency 97.6
Memory bandwidth 35.6

Command line: Geekbench4 --no-upload --memory-workers 56
Memory copy 37.5 gb/sec
Memory Latency 219.2 ns
Memory bandwidth 43.2

Processor Information
  Name Intel(R) Xeon(R) Gold 5120 CPU @ 2.20GHz
  Topology 2 Processors, 28 Cores, 56 Threads
  Identifier GenuineIntel Family 6 Model 85 Stepping 4
  Base Frequency 2.19 GHz
  Maximum Frequency 3.19 GHz
  Processor Package Socket 3647 LGA
  Processor Codename Skylake-E/EP
  L1 Instruction Cache 32.0 KB x 14
  L1 Data Cache 32.0 KB x 14
  L2 Cache 1.00 MB x 14
  L3 Cache 19.3 MB

There is a 192 GB of ram (12x16GB)of DDR4 2666 Ram which slows to 2400 due to the processor.

I have included the command line results and the command lines I used, and the GUI run. Any help would be appreciated as to why it makes a difference.

  1. Support Staff 1 Posted by Sarah on 07 Jun, 2018 06:55 PM

    Sarah's Avatar

    Hi jwarner,

    Thanks for posting and for attaching the files. Are you able to provide a .gb4 file containing the benchmark results from the GUI? Are you also able to take a screenshot of what it looks like in the task manager while you run the benchmark using the GUI? I'd like to take a closer look at what this looks like on your end.

    Thanks,

    Sarah
    Primate Labs Inc.

  2. 2 Posted by jwarner on 07 Jun, 2018 07:01 PM

    jwarner's Avatar

    Greetings Sarah,

    So you would like a .gb4 file run from the GUI and from the command line with the –memory-benchmark 56 correct?
    Yes I can take screen shots I assume you would like a screen shot for both cases as well?

  3. Support Staff 3 Posted by Sarah on 07 Jun, 2018 07:08 PM

    Sarah's Avatar

    Hi jwarner,

    Yes, exactly. That would be super helpful if you could attach one for the command line as well.

    Thanks,

    Sarah
    Primate Labs Inc.

  4. 4 Posted by jwarner on 12 Jun, 2018 03:12 PM

    jwarner's Avatar

    Added GUI screenshot using 56 threads and GUI run GB4 file.

  5. 5 Posted by jwarner on 12 Jun, 2018 03:25 PM

    jwarner's Avatar

    Command line runs and screenshots.

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