[PD] new raspberries

[Pierre Massat]

This is so exciting. Unfortunately they're out of stock now !

2015-02-10 0:05 GMT+01:00 katja <katjavetter at gmail.com>:

> Using the following command to check cpu frequency on RPi model 2B:
>
> sudo watch -n 1 cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
>
> I found that RPi model 2B does frequency scaling by default (nothing
> modified in /boot/config.txt). It switches between 600 and 900 MHz.
> This doesn't really give substantial power saving so I wanted to
> replace 'ondemand' governor with 'performance' by setting
> 'force_turbo=1' in config.txt. But this caused all sorts of
> instabilities, at least in combination with Pd, and I had to disable
> turbo.
>
> So there's two things going on which Pd doesn't like: frequency
> scaling and core switching. Both happen on my core2duo laptop as well,
> where Pd doesn't have a problem. Anyway, pd's '-nosleep' option saves
> the day.
>
> Now for the good news: performance gain. I compared model B+ with 2B
> by running instances of Martin Brinkmann's chaosmonster1.pd
> (http://www.martin-brinkmann.de/pd-patches.html) at default samplerate
> and with 10 ms buffer. Model B+ can run one chaosmonster without
> xruns, but not two. Model 2B can run five instances of
> chaosmonster1.pd without xruns, while the GUI remains fully
> responsive. This is not poor Pi as we know it, it's a different beast.
> I must say that puredata 0.46-2 was compiled from Raspbian jessie
> source on the Pi itself in both cases. This process uses GNU autotools
> which may have set platform specific optimizations. In any case,
> performance gain is much more substantial than I would expect.
> Hopefully I'm not dreaming.
>
> Katja
>
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