[PD] PD and latency on kernel

thewade pdman at aproximation.org
Fri Nov 18 20:58:43 CET 2005

derek holzer wrote:

> Hi Wade,
> thewade wrote:
>> How do I tune PD to run as fast as possible?
> I'm sure you have a lot of these covered already!
> * Run as root (or with LSM).
> * Run with the -rt flag.
> * Ditch Gnome and use something super-lightweight like fluxbox.
> * Make sure there is no IRQ conflicts between your graphics card, 
> sound card and peripherals:
> --> http://tinyurl.com/7vhmc
> * Using a shared-memory graphics card, such as the Intel chipset Frank 
> Barknecht discussed with Ed Kelly this week, is reported by RME to 
> cause dropouts:
> --> http://tinyurl.com/dcdvk
> * Also look into your hard drive access times if any disk activity 
> needs to happen during performance:
> --> http://tinyurl.com/cedtl
> * Realtime, low latency kernel patches (does not apply to PPC 
> achitecture!)
> * Check out Linux Security Mode patches to run RT as non-root.
> * Don't use frequently-updated graphics in your patches (i.e. VU 
> meters or number boxes connected to a fast stream of numbers, etc etc).
> * Run one instance of pd -noaudio for your GUI, and use OSC to 
> communicate with another instance of pd -nogui for your DSP. The poor 
> man's multithreading!
> * Only start PD with as many ALSA/JACK channels as you need.
> * Consider using -nodac/-noadc if they are not needed.
That kicks arse! I am using fluxbox now. I installed it last night 
(building tools like that is good busywork to distract from the 
hangover). It just died on me when I switched workspaces though...
Someone should post this on some wiki somewhere!
I am going to look into the irq issue as someone on the LAU list 
mentioned this as well.
A couple of questions though:
Does it help to run PD using nice? e.g. 'nice -5 pd' and jack with a 
priority of 70 or so?
if I use -jack in my pdrc then -rt does nothing, right? I thought -rt 
wsa for alsa opperation.
Thanks again for this list! I did cover many of thoes points, but I 
forgot a lot of them as well!

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