Sounds similar to the issue I spoke of here a week ago.
If its the latest Qjackctl built with QT4, its a QT4 problem of yet
to be defined origin. Only difference I had, going by your description, was that
My CPU was running at 99% and staying there.

If you run jack from the command line and see normal Cpu, this
would point to the same problem.

I have not yeilded a root cause from my Googling. Only some 
similar instances from other users, not only with Qjackctl & Qsynth,
but also Skype and others built with QT4.

My fix for now was to revert to an older version of qjackctl.

Thanks!



On Apr 5, 2008, at 10:26 AM, Mysth-R <mysthr21@gmail.com> wrote:

Hello list,
Since I have installed Gentoo I got some issue with JACK. I am using Jackdmp
When I run qjackctl all is right but the CPU percent, in spite of staying around 3 or 4% it is moving : 4% then 3 %, then it passes to 27% then 10% and 53% and 4%  ...

I don't understand very well what it is going wrong.
My config :  gentoo 64 bits version on a Dell Insprion 9400 Intel Core Duo 2 T7200 with 2 Go Ram.
Firstly I had installed jack 0.109 and the issue was worse that jackdmp :sometimes CPU load until 80%

The kernel I use was compiled by my own. Perhpas I forgot an option or something...
uname -a  :
2.6.24-rt1 #4 SMP PREEMPT RT Sun Mar 16 21:42:41:CET 2008 x86_64 Intel(R) Core(TM)2 CPU T7200 @ 2.00GHz GenuineIntel GNU/Linux

Thank you very much for your help.

Cheers,
Mysth-R

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