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BBB USB Transfer Rates

Tiago Pinheiro73
Prodigy 30 points
Other Parts Discussed in Thread: AM3359

Hi all,

I have a device that requires transfering 3MP raw images to a BBB as quick as possible, using USB. I've been trying to make it work but it seems that even with DMA enabled I can't get no more than 11 MB/s read speed. I've tested this with multiple kernels. The best one was the 3.14.26-ti-R41.

My question is...is this the maximum I can expect to get from the AM3359? If not, how can I go any further?

As a note, I can also say that the processor frequency influences the USB transfer (read or write) speed. Read speeds can go from ~6.5MB/s @300 MHz to ~11 MB/s @1 GHz. I've compared this with the competition (RPi) and it can achieve (the same test, processor @ 700 MHz) ~26.5 MB/s.

Thank you and wishes of a great 2015 to everyone.

  • 0
    TI__Mastermind 27890 points
    Please refer to the following for USB (and other) interface performance metrics:
    http://processors.wiki.ti.com/index.php/Sitara_Linux_SDK_Kernel_Performance_Guide#USB_Driver
  • 0 in reply to -DK-
    Prodigy 30 points
    Hi DK,

    Thank you for your answer. In fact I already knew about that information. That is the point. If those are the values expected, how come no one can achieve them? Until now I haven't found a single person that confirms anywhere near that values.

    Thank you.
  • 0 in reply to Tiago Pinheiro73
    TI__Mastermind 27890 points
    Hi,
    Are you saying that both read AND write are limited to 11MB/s? Could you outline your test topology and the devices in use?
  • 0 in reply to -DK-
    Prodigy 30 points
    No, that's not what I'm saying. The test conditions were:

    Machines: Beaglebone Black, Kernel 3.14.26-ti-R41 (this Kernel was the one were I could get better results), processor running at 1 GHz.
    Test: Write 3MB to a USB Flash Drive attached directly to BBB. Read the same 3MB from the Flash Drive (clearing cache);

    Transfer rates achieved (average for 10 retries):
    Write: ~33 MB/s
    Read: ~11 MB/s

    In the RPi I could achieve (same test conditions, same USB Flash Drive):
    Write: ~43 MB/s
    Read: ~26.5 MB/s

    Thank you.