Subject: Re: [linux-audio-dev] It's time to vote (n. 1)
From: Jörn Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Thu May 24 2001 - 14:53:56 EEST
Steve Harris wrote:
>
> On Wed, May 23, 2001 at 07:25:37PM -0400, Paul Davis wrote:
> > >> I'm just wondering, since I'm getting a .7 ms roundtrip time when
> > >> pinging my other Linux system here, which is connected to this one
> > >> by 100 Mbps ethernet through a 100 Mbps switch. Is that number
> > >> for real? Because it seems almost too good.
> > >
> > >I get 150-250usec (yes, microseconds) roundtrip through 100mbps switch.
> >
> > is this on a previously quiescent connection (TCP or UDP) ? my
> > impression is that once things get rolling round trip times are pretty
> > good, but that moving a packet or two when there's been no traffic in
> > a few msecs produces much worse numbers. my impression may be wrong.
>
> This is definatly true on ATM, the ramping up time is more like 30 seconds
> though.
>
> Over ethernet it seem to be only the first packet that is slow, probably
> depends on the make of switch though. Unswitched private networks should
> be fine. But as Paul said these times are too slow to be useful.
even if larger switched networks are unusable, it would still be a
nice option to be able to connect two audio boxen via a dedicated
100mb ether network to use their combined power for audio
applications.
at 20 US$ per card and 10$ for a crosslinked cat5 cable, this is a
dead cheap solution for studios.
are there any obstacles in this setup i have overlooked ?
from my experience, ping latency is well below 500 usecs. if that's
a measure for the actual audio latency, we'll be doing fine.
i must confess i don't see all the implications of net transparency
for our glue api, but boy would it be cool.
does the low-latency patch cover network drivers ? or can network
traffic be stalled when the box is busy ?
-- Jörn Nettingsmeier home://Kurfürstenstr.49.45138.Essen.Germany phone://+49.201.491621 http://icem-www.folkwang-hochschule.de/~nettings/ http://www.linuxdj.com/audio/lad/
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