[Jack-Devel] intel_pstate vs. jack?

Hi all,

New upgrades (Fedora 20), new kernels and suddenly I don't seem to get 
the performance I used to from jack & friends (no hardware changes, 
using a pretty beefy workstation with 6 core processor and 64G ram), I'm 
seeing xruns when I used to have very solid performance[*].

To make the story short, I used to change the cpu frequency governor to 
"performance" and set the frequencies to the maximum to get the best out 
of jack. I have read many of you have no problems using jack with 
frequency scaling active, but that has not been my experience. But I was 
surprised to find the frequencies fluctuating even after telling my 
computer to not change them... sigh...

I found that the method of controlling frequency on new cpus has changed 
(apparently as of 3.10.x) to the intel_pstate driver. Disabling it (you 
have to add intel_pstate=disable in the kernel command line and reboot) 
seems to have returned the system to its usual behavior although I need 
to test more.

Anyone our there also having fun with this??
Any recommendations?

-- Fernando


[*] running a LOT of software, several instances of jconvolver, two of 
ambdec, a big ardour session, supercollider, etc, etc. All cores 
fluctuate around 30-50% of capacity.

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