[PlanetCCRMA] The JACK Story

Orcan Ogetbil oget.fedora at gmail.com
Sat Nov 21 23:58:16 PST 2009

On Sun, Nov 22, 2009 at 12:37 AM, Fernando Lopez-Lezcano wrote:
> On Sat, 2009-11-21 at 23:20 -0500, Orcan Ogetbil wrote:
>> On Sat, Nov 21, 2009 at 10:55 PM, Fernando Lopez-Lezcano wrote:
>> > On Sat, 2009-11-21 at 22:02 -0500, Orcan Ogetbil wrote:
>> >> Would you like to have them parallelly installable? We can achieve
>> >> parallel installation via "alternatives".
>> >
>> > I'm not completely sure if that is possible. Keep in mind that all jack
>> > server and client _libraries_ need to be switched in and out (ie: it is
>> > not just a matter of switching the jackd binaries.
>> >
>> I am confident that we can handle it. Java, as a much bigger suite
>> with many libraries, does it. We will have to reside the actual
>> binaries+libraries in certain directories and alternatives will do its
>> magic with the symlinks.
> Ok, it would be worth trying. Having them both would be good. And the
> user can choose the default.
> What is the default default? :-), the last one installed? Sorry, I'm not
> familiar with the alternatives system.

As far as I know, "alternatives" has a priority measure that you
specify in the %post of your package. I don't know which one should be
the default. I use both from time to time and I can't decide. I would
say whichever is more stable.

> The priority I'm talking about is the one jackd runs at so it is
> internal to jack. I change the default in the source code to match
> rtirq's tweaked priorities. Jackd does not look for it anywhere, you can
> change it from the command line or qjackctl but it would be best to have
> the best choice be automatic for the rt kernel, of course :-)

So, what would priority 60 do with Fedora's kernel? Sorry I'm rather
ignorant with kernel related stuff. I run your jack2 on Fedora's
kernel quite frequently. Although I haven't done anything other than
simple 3-4 track recording recently, I didn't have trouble with the
current setting.

>> (By the way, the current convention is to use that folder rather than
>> editing limits.conf.)
> Ah, I did not know that. I should change my current package to do that
> instead of adding to limits.conf (when did this start? fc11?)

I think it started with F-11 but I'm not sure. You don't need to do an
update just for this change. Maybe next time you update the package,
you can do it this way.

> Thanks for bringing this up! I'm all for jack2 moving to Fedora proper,
> the trick would be to figure out the jackd rt priority stuff so that it
> can run under both kernels with no tweaking on the part of the user. No
> answer to that yet.... :-(

Yeah, it would be cool if we can figure out a best way. By the way,
(maybe I should have said this in the beginning) I don't maintain
Fedora's jack and I hope the current maintainer will cooperate.


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