Cannot lock down memory for RT thread (Cannot allocate memory)

hollunder at hollunder at
Sat Aug 2 19:16:29 BST 2008

On Sat, 2 Aug 2008 12:04:50 -0600
"holotone at" <holotone at> wrote:

> With my recent discovery of the awesomeness that is SooperLooper,
> today is the day that I'm really trying in earnest to get a click and
> XRUN-free setup going with my Behringer UCA200 audio interface. For
> your reference, here is a screencap of my current qjackctl settings,
> along with the messages pane during startup:
> This setup seems to work great (no XRUNS) except for the fact that
> there's a consistent "clicking" noise when I push it too hard, say
> with a polyphonic synth; With a higher Frames/Period setting, these
> same clicks were the sound that always preceded an XRUN, so it seems
> odd to me that it's not triggering any in this setup.
> Highlighted in the messages pane, you'll see the error message that
> has me worried:
> "cannot lock down memory for RT thread (Cannot allocate memory)"
> A quick search on this yeilds info that it may be related to not
> running my apps as root, a problem I was under the impression that
> UbuntuStudio solved:
> For what it's worth, it does appear that realtime is on, as the "RT"
> indicator flashes on and off periodically during operation.
> Any suggestions and / or ideas to get rid of these clicks and that
> strange error message?
> Thanks!
> ~holotone

Are you sure that the limits.conf stuff is set?
It can be done comfortably using the "Ubuntu Studio Controls" which can
be found in the administration menu.
Check 'rt' there and set the memlock value to something.. I usually set
it to 76%.

Good luck

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