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AM6442: DDR Bandwidth Testing Tools

Anjana Rao
Prodigy 50 points
Part Number: AM6442


Tool/software:

Hi,

I have been using memtester and stress for DDR testing, and they work well for stress testing. However, I am specifically looking for a tool that can display the bandwidth of DDR memory.

Could you kindly recommend any tools that would help in measuring DDR bandwidth?

Thanks,
Anjana

  • 0
    TI__Guru* 88450 points

    Please check https://www.ti.com/lit/pdf/spracv1  We usually use LMBench

    Regards,

    James

  • 0 in reply to JJD
    Prodigy 50 points

    Hello,
    Based on the output from /proc/meminfo, we see the following:
    MemTotal:        1842376 kB
    MemFree:         1627832 kB
    MemAvailable:    1671724 kB

    However, when I run the bw_mem tool with a request for 1.9GB (bw_mem 1.9G rd), it still displays the bandwidth results:
    1000.00 1343.56

    Could you explain why this happens and could you also clarify the measurement unit for the result obtained?

    Thanks,
    Anjana

  • 0 in reply to Anjana Rao
    TI__Mastermind 27050 points
    Anjana Rao said:
    However, when I run the bw_mem tool with a request for 1.9GB (bw_mem 1.9G rd), it still displays the bandwidth results:
    1000.00 1343.56

    Please attach the exact command you are running and the printouts. Asking for 1.9GB memory read in a system with ~1.6GB of memory free does not make sense, will probably lead to process getting killed. Anything above few hundred MB does not make sense, your application won't be able to use more than that in a system with ~1.6GB of physical memory. bw_mem is an open source program see for example https://github.com/tonyho/ARM_BenchMark/tree/master/lmbench/src for what it does and what are the limits, and https://www.ti.com/lit/pdf/spracv1 for an intro

    For a throughput test a few megabytes read will be representative, better to do multiple times that try to do a gigabyte level read.

      Pekka

  • 0 in reply to Pekka Varis
    Prodigy 50 points

    Hi,

    What is the unit for the bandwidth displayed in the output of the bw_mem command, as the unit is not explicitly mentioned?

    root@am64xx-evm:~# bw_mem -P 2 8M bcopy                                                                                                                                                                    
    8.00 1260.56

    Thanks,
    Anjana

  • 0 in reply to Anjana Rao
    TI__Mastermind 27050 points

    Please look at the links provided. From https://www.ti.com/lit/pdf/spracv1 

    The bandwidth is calculated as byte read and written counts as 1, which should be roughly half of STREAM copy result. The table below shows the measured bandwidth and the efficiency compared to theoretical wire rate.

    MB/s

      Pekka