rt kernel

[Ralf Mardorf]

On Mon, 2011-04-04 at 18:34 +0200, Victor henri wrote:
> Hello
> 
> I compile myself the preempt kernel usually.
> 
>  
> > 2011/4/3 Gerhard Lang <lang.gerhard at gmail.com>:
> > [...]
> > > buffersize/xrun ratio. For tedious audio work on standard hardware I see no
> > > more need for -rt kernels.
> > 
> > I would be very happy if we could live without -rt kernel.
> > 
> > > I guess there might be a little profit for audio
> > > performance by compiling actual kernel cgroups disabled, no tics disabled,
> > > preemptible kernel enabled and  timer frequency set to 1000hz.
> > 
> 
> For the preemptible kernel, I was aware of the "preemptible kernel" and "timer frequency = 1000Hz" options; 
> 
> Could please tell for the @ other otptions:
>     - for the cgroups disabled: is it the "General Setup -> Control Group Support" set to 'no'?

For my script, see
https://lists.ubuntu.com/archives/ubuntu-studio-users/2011-February/007299.html , I disabled it by:

echo "CONFIG_RT_GROUP_SCHED=n" >> .config

>     - for the "no tics" options disabled, is is the "Processor Type and Features -> High Resolution Timer Support" set to 'no'? If not, what is the option to be disabled?

For NO TICs/TICLESS you need to enable the HR timer. There isn't a HR
timer for every motherboard. HR timer is enabled by default for the
generic kernel, at least for Maverick.
You need to load the module and to enable access by the user, see
https://lists.ubuntu.com/archives/ubuntu-studio-users/2011-April/007430.html .
You can load the module at startup by adding a script to /etc/rcS.d,
perhaps it's better to keep it as a module.

> > This is exactly the -lowlatency kernel.
> > 
> > > optional manipulating devices' IRQ assignment and priorities like this was
> > > done by rtirq should be a feature for standard kernels.
> > 
> > I hope to provide soon a new -lowlatency kernel which provide that
> > feature (which is available in 2.6.39).
> > 
> > Ciao,
> > Alessio
> > 
> 
> Thank you
> 
> Victor
> 		 	   		  

Hth,

Ralf