[PD] Pd 20% idle CPU usage on MBP

Jamie Bullock jamie at postlude.co.uk
Mon Nov 8 13:15:03 CET 2010


On 7 Nov 2010, at 18:36, Hans-Christoph Steiner wrote:

> 
> As far as I understand it, Pd only does the 20% idle thing when its not really doing anything.  So if Pd is working hard, it'll stop spending 20% of the CPU idling.  I could be wrong tho, and that would be worth profiling.  That's the key point: is Pd efficient when its doing stuff, rather than whether it uses extra CPU when idling.
> 

- Pd uses X% of the CPU talking with audio drivers when it is idle (even if audio is off)
- When the audio driver is portaudio Pd uses ~20% of the CPU talking with the driver (under OS X on a 2.5 GHz MBP)

2 separate problems, the second being the most pressing.

And yes, ~20% is the base level, so as soon as you start adding processing, CPU load goes up from there...

I don't think portaudio is that great for realtime work, although I think this is bordering on worst-case (compared to other apps). I've a feeling the problem might lie in the buffer size used for passing audio to portaudio.

Jamie





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