[maemo-developers] Frequencies scaling with OS2008

[From: Simon Pickering]

> As ARM core is quite fast in N8x0, probably it would make sense to try
> keeping DSP out of the way whenever possible (restrict it to 133MHz only,
> keep DSP tasks which are fast enough to run at this frequency, port
> all the other DSP tasks to ARM)? That is unless improvements to support
> more intelligent DSP clock frequency selection are still possible.
>
> But for those interested in C55x development, Nokia 770 is still a very
> interesting device as it runs DSP at full speed.

It would be interesting to see whether the mp3 task (for example) can  
decode in real time when the DSP is run at 133MHz or are your  
audio/video sync problems because it's running too slowly? This would  
remove some load from the CPU and allow us to use the DSP for something.

I've done a quick test, and although one can't use gstreamer to decode  
two mp3 files at the same time (presumably as the dsp task doesn't  
support being loaded more than once due to the shared memory buffers),  
it's possible to decode AAC and MP3 at the same time without any  
glitches (though as they are mixed it does make listening a bit hard ;)

The loadinfo file in the sysfs doesn't appear to do anything useful  
(always produces 0.00% as the load) so I don't have any load figures  
to go with the test.


Simon