[ECOS] Hard-Realtime behaviour

[Fabian Scheler]

> > So you at least need to disable caches when you determine what the
> > worst case is, assuming the cache is actually helping you.
>
> What about invalidating the caches instead of disabling them before measuring
> the worst case execution time? (I am assuming sufficient cache size to fit
> both the system call and any interrupt handlers.) Especially if there are
> loops, that will make a big difference.

This is only an option, when you can ensure, that your code will not
be preempted. That also might be a reason why it is clever to switch
off caches within the running system (regardless what I mentioned in
my foregoing post ;-)): In a loop, for instance, you can be preempted
after every iteration, so you would have to invalidate the caches
after every iteration, otherwise, you determine some execution time
but not the worst case execution time.

Ciao, Fabian

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