[music-dsp] Pre-emptive kernel for DSP

Truong, Loc l-truong at ti.com
Wed Jun 9 12:01:52 EDT 2004


A process can be interrupted "any time" by a higher priority process or
processes that use certain kernel calls to preempt besides by the kernel
itself once time is up. This is the area that Real Time Linux addresses
for embedded application. For desktop PCs I don't think RT Linux is
available. So for music and DSP on desktops one will just have to either
live with the macro-response of the Linux package (about 1ms), or
implement a subsystem that has its own interrupt response.
Regards,
Loc.

-----Original Message-----
From: music-dsp-bounces at shoko.calarts.edu
[mailto:music-dsp-bounces at shoko.calarts.edu] On Behalf Of Payan, Remi
Sent: Wednesday, June 09, 2004 9:33 AM
To: a list for musical digital signal processing
Subject: RE: [music-dsp] Pre-emptive kernel for DSP


David,
Yes, precisely. "At any time" is the keyword here. This is exactly the
point I wanted to make ;)
Still, I would like to confirm this is what the "preemption" option of
the Linux kernel actually does.
Any reference will be appreciated.

To answer the original question, I doubt one can notice a difference,
unless running a sample-based processing, which traditional non-real
time kernels cannot do (or are not meant to do).
In terms of scheduling, it really is much more difficult to handle,
which is probably why it is observed as less stable. Furthermore,
experience shows that, like any recent feature, it might be buggy. 

Bottom line is I would not recommend enabling it unless it is critical
for your application. 

Cheers,
-Remi

> But anyway, a process can be interrupted at any 
> time before eating enterily its slice, if preemption is 
> activated, can't 
> it ?

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