[LAU] Qjackctl 3.2, QT4, KDE 3.5.9, high CPU usage

[hanaghan at starband.net]

I think you might be having a different problem.

I can run jack from CL and any app that pipes to it without problem.

I did a little poking around and I think it's a QT4 problem. Others report
issues running GUI based apps that are not jack compatible or even
necessarily directly related to audio at all. They do all have QT4 use in
common.

I reverted back to an older version of Qjackctl and it's works just fine
again. I'm not necessarily needing any of the features that Qjackctl 3.2
had anyway so it's not a big deal for me.

Meanwhile, I need to write this up elsewhere and send to Thac now I think
about it.

Cheers!
R

> I just ran into this issue as well on my Gentoo system after a fresh
> system  install. I started jack from the command line to see if the
> problem had to do  with qjackctl and it didn't cause any excess CPU
> usage, but then when I  started Ardour, the excess CPU usage started up
> again.
>
> If I'm having the same issue as you, it would seem that the problem
> occurs  when a GUI based jack app starts up. Perhaps it's a jack related
> issue with  realtime and GUI libs?
>
> -Reuben
>
> Back on Sunday 30 March 2008, hanaghan at starband.net was like:
>> Hi Rui,
>> thanks for the reply.
>>
>> Ok...just to add, I rebuilt from the SRPM (same spec file though) and
>> no change. I also installed Gnome and it does it from there as well,
>> just to further support your point.
>>
>> I will email thac and see if we can figure it out.
>>
>> thanks,
>> R
>>
>> > hanaghan at starband.net wrote:
>> >> Hi folks...
>> >>
>> >> I still running PCLinuxOS and using Thacś RPMś.
>> >>
>> >> Without version numbers of lots of libs, the version numbers in the
>> subject line are relevant to my system. Hopefully thatś
>> enough.
>> >>
>> >>
>> >> I set up a new box from the live CD and added all the audio stuff
>> from apt. Everything worked fine...I updated to Qjackctl 3.2 from
>> and older version even and still no problems. I then did a jumbo
>> update out of Synaptic...
>> >>
>> >> When I run Qjackctl or Qsynth in KDE, the CPU usage shoots to the
>> moon. This has happened on another install of the same distro in
>> the the very same sequence and manner. I dont think itś
>> Qjackctl that is the issue..otherwise it would have done it when i
>> first upgraded to 3.2 using QT4. Even though Qsynth shows the same
>> symptoms, pointing toward a possible QT4 issue, that makes no sense
>> either...again, it would have done it before.
>> >>
>> >> I suspect something in KDE is doing it. I tried running from
>> Fluxbox, and same thing...but doesn Fluxbox use some KDS libs
>> anyway?
>> >>
>> >> I guess I can install Gnome and try that but really dont want the
>> clutter on the machine. Anyone know anything about this? I saw
>> another post on Linuxquestions.org about the same thing on another
>> distro...
>> >>
>> >> TIA for any help.
>> >
>> > a very similar issue has been experienced before, iirc. it has been
>> reported that on debian etch and ubuntu, qjackctl 0.3.x was peaking
>> to 100%cpu usage (not %dsp load) and right after jackd is started.
>> >
>> > this issues blame has been pointed to libqt4 itself, more
>> specifically to the QProcess class wich deals to process interface
>> coordination and to the extent of my knowledge a mere qt4 upgrade,
>> from the testing (or lenny) repositories, sufficed for the issue go
>> away.
>> >
>> > so it seems to be a strict qt4 issue, maybe related to the way it's
>> built but not sure (i never had the issue duplicated myself)
>> >
>> > hth
>> >
>> > cheers
>> > --
>> > rncbc aka Rui Nuno Capela
>> > rncbc at rncbc.org
>>
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