[Jackit-devel] Re: [linux-audio-user] Re: quattro

Jack O'Quin joq at io.com
Sun Nov 9 11:16:09 EST 2003

Patrick Shirkey <pshirkey at boosthardware.com> writes:

> Brian Redfern wrote:
> > If I run jackd as root it freezes my machine, but if I run it as as a
> > normal user that it hasn't frozen, but as root after about 2 minutes it
> > totally freezes up.
> >
> This doesn't happen for me.
> I use jack + quattro with a celeron 1 Ghz pIII, ASUS microATX mobo,
> 512 MB RAM, sis630 VGA.
> kernel-2.4.21-ll
> usb-ohci.
> gcc-2.95.4
> enlightenment-0.16.x
> alsa-driver-0.9.4 (Jul 31 2003 cvs)
> jackd-0.90 tarball which Paul made because I cannot compile cvs for
> some reason.
> I can run for hours without dropouts as root with:
> jackd -v -R -a -d alsa -d quattro2 -p 1024 -n 3 -zt

Thanks for the report, Patrick.  I added your comments above as a
bugnote to Mantis bug #0000016.  It's quite possible that Brian's
problem might be fixed in current CVS.  I don't know, he still has not
told us what version of JACK he is using.

BTW, Mantis allows anyone interested in a problem to monitor that bug
report.  You get e-mail whenever bugnotes or status changes happen.

> jackd seems to be happy as long as the late driver wakeup doesn't
> exceed 3072. Maybe this could be enforced somehow to make a simple fix
> for USB devices. Although I would rather see the complete solution
> implemented. (hint hint nudge nudge).

I suspect that what you are seeing is the continual latency slippage
as the USB cycle gets more and more out of sync with the JACK cycle.

The solution that has been discussed should address this.  It is
non-trivial to implement, so I don't want to start messing with the
buffer management again until we finish repairing the damage from the
last set of changes in that area.

With all the complaints we've heard about USB block size problems, I
am surprised that so far no one has opened a Mantis feature request to
get it resolved.  Would you be willing to do that?


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