RE: [beagleboard] Use PRUSS to measure Linux's realtime behavior

[Gregory Perry]

>________________________________________
>From: beagl...@googlegroups.com [beagl...@googlegroups.com] on behalf of Ronny Meeus [ronny...@gmail.com]
>Sent: Sunday, January 20, 2013 1:41 PM
>To: beagl...@googlegroups.com
>Subject: [beagleboard] Use PRUSS to measure Linux's realtime behavior
>
>Hello
>
>I want to use the PRUSS to measure the realtime behavior of Linux in different configurations. Some examples:
>- the pruss generates periodically interrupts that are "acknowledged" by the Linux SW. The pruss measures the delay and variation of the reaction time of the Linux code.
>- Linux generates periodically triggers to the pruss, which measures the delay between 2 events and keeps the largest,smallest and average value.
>
>In this setup the beaglebone can be used to get a view on the Linux's behaviour in different configurations, like with and without RT patch, when using Xenomai, under >load or when running IDLE etc.
>
>Is such code already available somewhere or does somebody have good references to examples that I can use to get started.
>
>Please note that I have no experience with writing SW for the PRUSS.
>
>Thanks,
>Ronny

That's a really neat idea.

Some links:

http://elinux.org/ECE497_BeagleBone_PRU
http://blog.boxysean.com/2012/08/12/first-steps-with-the-beaglebone-pru
http://www.youtube.com/watch?v=1irR4TQ5aMA

[Tallak Tveide]

There is some discussion about measuring real time behavior in the following book. I suggest you read the real time chapters and perhaps may save you some time coding. http://books.google.nl/books?id=I-hVqkX6A9cC&printsec=frontcover&hl=no#v=onepage&q&f=false

The book is called 'Building Embedded Linux Systems'

[Alexander Holler]

Am 20.01.2013 19:41, schrieb Ronny Meeus:
> Hello
>
> I want to use the PRUSS to measure the realtime behavior of Linux in
> different configurations. Some examples:
> - the pruss generates periodically interrupts that are "acknowledged" by
> the Linux SW. The pruss measures the delay and variation of the reaction
> time of the Linux code.
> - Linux generates periodically triggers to the pruss, which measures the
> delay between 2 events and keeps the largest,smallest and average value.
>
> In this setup the beaglebone can be used to get a view on the Linux's
> behaviour in different configurations, like with and without RT patch, when
> using Xenomai, under load or when running IDLE etc.
>
> Is such code already available somewhere or does somebody have good
> references to examples that I can use to get started.
>
> Please note that I have no experience with writing SW for the PRUSS.

Maybe browsing around at osadl.org will reveal some infos. They are
doing a lot with realtime, e.g. here is a bench from an OMAP system

https://www.osadl.org/Latency-plot-of-system-in-rack-2-slot.qa-latencyplot-r2s2.0.html

and also are offering a lot of other informations, e.g.

https://www.osadl.org/Single-View.111+M5f6c0e654c7.0.html

is worth to read.

It's unlikely that they use the PRUSS but maybe you can catch some other
ideas there.

Regards,

Alexander