hi all
i encountered, that 'ondemand' cpu scaling doesn't work correctly when running pd with realtime priority. even if pd is using 80% or more resources (of one core), the cpu frequency is not raised and staying at 800MHz. i can force it to go up by running an instance of 'burnMMX' (or something else, that burns as many cycles as possible). when running pd with '-nrt', automatic scaling works fine. also, as a workaround, i can set the scaling_governor to 'userspace' and then set the cpu frequency manually.
could it be, that when pd is running in realtime mode, its priority is higher then the one of the process, that controls the cpu frequency, so that cpu time is assigned rather to pd and only at times, when pd is not using it, the governor can adjust the frequency (which would be the loweset, since pd is not using much cpu at that time)?
i wonder, what other people do in a performative situation? do you simply turn automatic scaling off and set frequency to the highest value? or is it only me having this issue?
while we are at priorities: i figured out, that all four combinatios are possible: pd -rt, jackd -R pd -nrt, jackd -R pd -rt, jackd pd -nrt, jackd
i guess, that the first one should be used for best performance, right? but how to set priorities between jackd and pd? can this be fine-tuned at all (i know you can fine-tune jackd) ? if so, which should have higher priority?
roman
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