[LAU] Kxstudio RT kernel vs low latency

[Jeremy Jongepier]

On 07/24/2014 09:16 PM, Russell Hanaghan wrote:
> 
> 
>> On Jul 24, 2014, at 12:06 PM, Jeremy Jongepier <jeremy at autostatic.com> wrote:
>>
>>> On 07/24/2014 08:18 PM, Russell Hanaghan wrote:
>>> Hey,
>>>
>>> Is anyone achieving significant audio latency gains or xrun stability using a RT kernel with Kxstudio or similar Ubuntu studio distro's? 
>>>
>>> If so, which kernel / where /do I gotta roll my own?
>>>
>>> Thanks!
>>>
>>> ~ Russell
>>
>> Hi Rusell,
>>
>> I'm using stripped down Ubuntu installs with 3.2 and 3.8 RT kernels
>> which I roll myself. RT kernels allow me to achieve slightly lower
>> latencies and a bit more stable systems. But I don't think this is all
>> due to the RT kernels, it's also doing the right tweaks with the right
>> tools.
>>
>> Jeremy
>>
> 
> Thnks Jeremy,
> 
> Anything specific of notable effect? 
> 

No not really. With a lowlatency kernel I can barely run my audio
interface at 8 / 3 @ 48kHz which works in a bit more stable way with a
RT kernel. I typically run at 64 / 3 and then xruns pop up faster with a
lowlatency kernel compared to a RT kernel.

You write:
"But in testing with Enlightenment, also killing all unnecessary
processes, it really appears to make very little difference to how
firewire interface performs.

Running Mixbus 2.5, 8 mono trx, 5 Harrison plugins (EQ, master EQ, etc).
 Older laptop... Sony Vaio dual core 1.6ghz, 2g, firewire Maudio solo.
Disabled ACPI stuff, wireless and so forth. 256 / 3 is barely stable
with plugins not running w/ record."

So you're using FireWire, in that case the FireWire host controller
chipset is key, maybe you could post the output of ffado-diag. Also
getting the IRQ prios right can make a huge difference when using FireWire.


Jeremy

> I've read up on most of it I think. Top items;
> 
> Shut wireless networking off.
> Dedicated irq to audio device.
> Kill or disable power saving stuff
> Minimize background proc intensive processes.
> 
> Realtimescan app reports all is well bar no RT kernel. Typical recording is at 44.1/16. 
> 
> Thnx
> R
> 


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