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How to test interrupt latency (AM3517, PSP-SDK-03.00.01.06)?

Reinyn Bedlington
Intellectual 380 points
Other Parts Discussed in Thread: AM3517

I was wondering what a good way to test the interrupt latency on a 3517 would be (under Linux)?

On Windows CE there is a  Intrtime.exe utility, but I'm not sure if Linux has a equivalent test.

thanks,

-Reinyn

Also if anyone has any interrupt latency numbers under Linux that would be great.

  • 0
    TI__Mastermind 44306 points

    There are RT test tools that are normally used with RT-preemption patches:

    https://rt.wiki.kernel.org/index.php/Cyclictest

    On a 'normal' Linux Kernel (depending on version) you might see max latencies for task switching in the ms range. Using the RT-patch e.g. for 2.6.33.7 you can get this down to <100us. You may also look at the OSADL QA web farm where an AM3517 board is running RT Linux.

    Regards.

  • 0 in reply to Frank Walzer
    Intellectual 380 points

    Thank you,

     

    The Cyclictest program seems very useful. Do you know the proper command to cross compile it for the 3517? I am using Ubuntu with Code Sourcery. I tried

    make CROSS_COMPILE=arm-none-linux-gnueabi

    but that didn't seem to work (the Cyclictest program compiled for the host Ubuntu environment).

     

    Thanks,

    -Reinyn

  • 0 in reply to Reinyn Bedlington
    TI__Expert 4590 points

    You may want to try:

    make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi-

    Note the "-" at end of CROSS_COMPILE

  • 0 in reply to Sanjeev Premi
    Intellectual 380 points

    I gave up on compiling it for the AM3517 for now. Even after opening it up as a makefile project in Code Sourcery I could only ever get it to build the x86 version.

  • 0 in reply to Reinyn Bedlington
    TI__Expert 4590 points

    I jut browsed through the Makefile. It uses CC for compiler.

    I am not sure about how CodeSourcery projects handle the compiler definitions - but on command-line that would always translate to the host gcc. And you'll get a native binary.

    To cross compile, you'll need to do following (ideally in a shell script - that can be sourced when required):

    1) Ensure that codesourcery tools are in your current path

    2) Re-define all tools to corresponding codesourcery tools e.g, (in bash):

    export CC=arm-none-linux-gnueabi-gcc

    export LD=arm-none-linux-gnueabi-ld

    export AR=arm-none-linux-gnueabi-ar

    3) source the shell script and try build once again.

    Only one issue I see is dependency on librt - not sure if you have it in your devkit.

    EDIT: I just verified that "librt" is part of the default codesourcery distribution (in arm-none-linux-gnueabi/libc/lib directory). So, there should be no issues.

  • 0 in reply to Sanjeev Premi
    Intellectual 380 points

    Thank you!!! I was able to build the "cyclictest" app and run it on the 3517.