[linux-audio-user] JACK ports

Paul Davis paul at linuxaudiosystems.com
Mon Feb 6 13:40:11 EST 2006


On Mon, 2006-02-06 at 10:29 -0800, Ruben Lopez wrote:
>  On Mon, 06 Feb 2006 13:03:53 -0500, Paul Davis wrote:
> > On Mon, 2006-02-06 at 07:52 -0800, Ruben Lopez wrote:
> >
> >> In JACK, if the number of Maximum Ports is increased, does JACK
> >> use more system resources? If not, is there a down side to having
> >> a high number of ports?
> >>
> > it uses more shared memory, yes. each port consumes a relatively
> > small amount (basically period_size * 4 bytes plus a small constant
> > overhead).
> 
> So is this overhead enough to make an significant impact on latency, or is it too minimal to worry about?

either you have the physical RAM to support it (likely), in which case
it doesn't make a lot of difference. or you don't in which case its a
disaster.

the more clients you have and the more memory they touch while running,
the greater is the overhead of JACK's "independent process" model. the
effect is not negligble if you were already close to the limit of the
machine, but if you had plenty of headroom already, its not worth
worrying about.

--p





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