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.

over 14 years ago

0 Frank Walzer over 14 years ago

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 Reinyn Bedlington over 14 years ago 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 Sanjeev Premi over 14 years ago 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 Reinyn Bedlington over 14 years ago 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 Sanjeev Premi over 14 years ago 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 Reinyn Bedlington over 14 years ago in reply to Sanjeev Premi

Intellectual 380 points

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

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