[Asterisk-Dev] Re: ztdummy accuracy improvements on kernel 2.6

[Tony Mountifield]

In article <20050516053559.A99342 at xorpc.icir.org>,
Luigi Rizzo <rizzo at icir.org> wrote:
> On Mon, May 16, 2005 at 11:06:16AM +0000, Tony Mountifield wrote:
> > I've been using MeetMe via IAX with no problems on a FC1 box with the
> > 2.4 kernel and zaprtc for timing.
> > 
> > Recently I've set up a FC3 box with the 2.6 kernel, and have been using
> > ztdummy for timing. Using the same IAX sources to a MeetMe conference,
> > I found that there was an increasing delay between a participant speaking
> > and the others hearing him. Over 10-20 minutes this crept up to several
> > seconds!
> 
> i am unclear on one thing -- if there is such a delay, a queue
> somewhere must grow very long, and i wonder if this couldn't be
> used as a hint that there is clearly a timing mismatch that
> should be compensated.

I think what is happening is that the zaptel processing invoked by ztdummy
is not happening quite often enough due to missed jiffies. Consequently
I suspect the incoming IAX channels are not being serviced often enough,
and are building up a backlog.

Certainly, changing ztdummy to use the hardware timer in the RTC seems to
fix the problem nicely.

Cheers
Tony
-- 
Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org