[PD] how to optimize system for pd performance?

[Roman Haefeli]

you might have guessed it, but for the sake of correctness:

this is:
- linux / ubuntu hardy
- intel core 2 duo (800 -> 2401 MHz)
- pd vanilla 0.42 test5


On Sun, 2008-12-07 at 16:58 +0100, Roman Haefeli wrote:
> 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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