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Re: Hard-Realtime behaviour


> 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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