[music-dsp] DOS [or DOS mode] for low latency on PC?

David Olofson david at olofson.net
Tue Jan 6 10:48:01 EST 2004


On Tuesday 06 January 2004 18.55, Martin C. Martin wrote:
> > I need low latency between input and output for my
> > processing algorithms.
> > However Windows has horrible latency.
>
> Too bad BeOS died...

For "BeOS class" latencies, you could try Linux with lowlatency and 
preempt patches. It's usually no problem to get rock solid processing 
with less than 3 ms latency with decent hardware and a good 
lowlatency kernel.

	http://www.linuxdj.com/audio/lad/resourceslatency.php3

(Note that "decent hardware" means "no nasty BIOS super-NMIs or other 
RT killers", rather than "insanely fast CPU". Not even an industrial 
RTOS can do much about BIOS NMIs and chipset bugs. All you can do is 
try to disable power managment and similar crap in the BIOS. Also 
stay miles away from BIOS text emulation on video chipsets without 
h/w text modes. If you have one of those beasts, try using fbdev, to 
get Linux to do the text "emulation" instead of the BIOS.)

Unfortunately, the 2.6 kernel hasn't quite delivered the kind of real 
time performance we hoped for yet, but there are older versions that 
perform well and are pretty solid. I've had great results with good 
old 2.2.10-lowlatency. Never got any later versions to perform that 
well myself, though I haven't really tried to tune a Linux/lowlatency 
system in a good while.


//David Olofson - Programmer, Composer, Open Source Advocate

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