[PD] PD and cpu freq scaling in Linux

[danomatika]

Howdy,

I recently got a new Thinkpad T500 with a duo core 2.53Ghz processor
running Ubuntu Intrepid and was a bit annoyed that I was getting far
more audio DIO dropouts in PD than my previous single core Pentium M
2Ghz Thinkpad T42p.

Last night I realized that the cpu frequency scaling was actually
interfering and running both cores at 800Mhz while I had Jack and PD
running in realtime mode! I had little to no dropouts on the T42p since
the OnDemand scaling algorithm used by default only had one core to do
the work and automatically bumped the cpu to max freq.  With two cores
it seems to think it can keep the freq lower and I get dropouts.

For those of you who might have noticed the same problem ("WTF! How can
my NEW FAST machine be running PD like crap!!??!"), you can set the cpu
scaling manually.  Once I set my machine to Performance it bumped the
speed to max and PD runs smooth as silk.

(I highly recommend this machine BTW, it is super quiet and super cool
temperature wise.  My previous Thinkpad feels like a hurricane toaster
by comparison)

In Gnome you can add the CPU Frequency Scaling Monitor applet or you can
use the commandline.  SUID root control of the applet is enabled in
Intrepid, so you can skip the sudo dpkg-reconfigure gnome-applets step.

Hope this helps.
---
Dan Wilcox
danomatika.com
robotcowboy.com
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