Re: [RFC] [rt-tests] change to cyclictest behavior

Clark Williams
2010-01-07T14:47:13Z

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On Thu, 07 Jan 2010 08:23:52 +0100
Carsten Emde <Carsten.Emde@osadl.org> wrote:

> Clark,
>
> >> -S --smp Standard SMP testing (equals -a -t -n -d0),
> >> same priority on all threads.
> After having done some tests with a quickly hacked cyclictest version, I
> have found an issue with including -d0. Apparently, small numbers make
> life especially difficult for the scheduler; this is why we often used
> -d1. Specifying -d0 seems a special case where all threads are in sync.
> Maybe, we may miss some important latency constellations, if we do not
> let the tasks slightly interfere. In any case, I would like to be able
> to specify a distance _in addition_ to -S. This would create a scenario
> where
>
> cyclictest -d1 -S
>
> results in a distance of 0, and
>
> cyclictest -S -d1
>
> results in a distance of 1. Would this be acceptable?
>
> Carsten.

I don't have a problem not having -d in the -S option. I was looking at
the possibility of synchronous sampling as well so it's probably a good
idea to keep it separate.

The main things we want are implied -t, -a and -n.

Clark

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