[PD] PD and latency on kernel 2.6.14.2-lsm

Peter Plessas plessas at sbox.tugraz.at
Fri Nov 18 23:01:47 CET 2005


Hi,

on my boxes it helped to set the nice value of the xserver from -10 to 0 
(on debian -10 seems to be the default). You can set it in 
/etc/X11/Xwrapper.config.

see also:   http://plessas.mur.at/audio_computer.html

apropos jack: i always thought that pd's -rt flag and jackd's -R are two 
different things...?

peter

thewade wrote:
> 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!
> -thewade
> 
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