Re: rt kernel, pro-audio use

[Clark Williams <williams@redhat.com>]

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On Wed, 19 Dec 2012 21:30:29 +0000
Damien Moody <webmaster@gentoostudio.org> wrote:

> Hi,
> 
> I have a couple of questions.
> 
> 1. I'd like to keep informed when the rt kernel gets updated, so I can 
> put up a new Gentoo ebuild on my site (gentoostudio.org). Is this the 
> list for that? If not, what is?
> 
> 2. I use the rt patches a la rt-sources on Gentoo. I'm a musician and 
> audio engineer. What advantages does the rt patch set provide over other 
> patch sets like ck-sources and pf-sources, where latency can be 
> configured to be very low? I'd like to document this on my site.
>

I use an RT-patched kernel with Fedora to record drum tracks with
Ardour3+jack+ffado. I can record 16-channels of 24-bit samples at
48000Hz through a pair of Presonus FP10s attached to a Lenovo W510
laptop and I honestly can't remember the last time I had an xrun. 

I'm sure plenty of people can do this with a standard kernel that's
been tuned but no matter how much they tune it, there's always the
possibility of running into a priority-inversion situation. The RT
patchset converts most of the spinlocks in the kernel to an
rt_mutext_t. The rt_mutex_t lock has a priority-inheritance chain that
allows for a temporary priority boost of a thread holding a lock when a
higher priority thread tries to claim the lock. This prevents
intermediate priority threads from preventng the lock-holder thread
from running, delaying the high priority thread indefinitely. 

Clark


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