Re: re0 fix that works with polling

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To: John-Mark Gurney <gurney_j@resnet.uoregon.edu>
Date: Mon, 18 Oct 2004 23:00:11 -0700

On Mon, 2004-10-18 at 22:33, John-Mark Gurney wrote:
> Sean McNeil wrote this message on Mon, Oct 18, 2004 at 16:25 -0700:
> > > Do you have a video that you could send me, that I could do some testing
> > > with this? (and vls config)? I've been doing my testing on an i386,
> > > but that shouldn't be different enough to cause problems... (if it is,
> > > then we need to think about what the re is behaving badly)...
> >
> > I have placed 11 megs of the stream in
> >
> > http://mcneil.com/~sean/freebsd/stream.mpg
>
> damn, is that hdtv quality?? :) looks pretty nice...

Yes, that is low-quality HD at 15mbps. It isn't too bad, though, until
it gets to a part I don't think was in the short sample I provided.
Gandalf is attacking the fire demon as they fall. Very blocky.

> > You can install vls from ports (net/vls) and I run it with
> >
> > vls -d udp:224.1.1.1:1234 file:stream.mpg
> >
> > I agree that your assesment appears to be accurate in identifying no
> > packet loss. Are you going through a switch or is this a cross from
> > machine-machine?
>
> The bad news is that it appears that I'm not dropping any packets at
> all... I'm using vlc on my mac (which is also at gige), and it appears
> to be getting full data rate.. though things are gittery,but the logs
> are kinda wierd...

The mac probably doesn't have enough horse power. Typically you need an
Intel 3GHz processor to get it to play smoothly with software.

> now the bad part of the news... if I drop my re0 card over to my 100mbit
> switch:
> media: Ethernet autoselect (100baseTX <full-duplex>)
>
> Ok, here's a more complete run of what happened:
> re0 <-> SMC gige switch <-> NetGear gige switch <-> MacOSX laptop (gige)
> no packet loss observed.. ~1.9megs/sec or 1400pps received at MacOSX
> laptop
>
> re0 <-> summit48 (100mbit) <-> SMC gige switch <-> MacOSX laptop (gige)
> w/ or w/o netgear switch between SMC and laptop, packet loss is
> observed, only about 700-900kbyte/sec or 500-600pps

This is very interesting. This is completely opposite to my
experience. I have

re0 <-> linksys gige <-> hardware decoder or freebsd box just doing
capture both at 100bt

        packet loss. With mods, no loss.

re0 at 100bt <-> linksys 100bt <-> same as above

        no packet loss.

Could this be some sort of n-way negotiation issue?

> now a bit more information, I did use snmpnetstat on the switch to verify
> that the switch was receiving (but I forgot to verify that it was sending
> all packets to the gige port) all packets even w/ the final packet loss..
>
> re0 <-> summit48 (100mbit) <-> MacOSX laptop
> no packet loss observed... similar stats as to the straight gige above..
>
> now, I also tried receiving on win2k box, and I received a bit better
> frame rate.. I don't think my macosx laptop can handle rendering the
> data stream (or at least vlc doesn't know how to make use of the proper
> acceleration).. the frame rate was really choppy, and sound not to good..

Yes, that would be expected. Fastest laptop being a 1.5GHz and vlc may
not be taking advantage of altivec. But then again maybe it is. Never
tried it on mine.

> Do you have an application that gets good stats from vlc? I did see
> a few messages in the message log about dropped packets... but I coudln't
> really figure out how many/much they were, and considering it was udp,
> I expected some loss...

The best thing I can recommend is to just capture the stream. I have a
program at

http://www.mcneil.com/~sean/freebsd/stream.c

just compile as cc -o stream stream.c and run as

./stream 224.1.1.1:1234 >capture.mpg

assuming address:port as before.

I have another program that will compare the streams and report missing
packets if you find that they appear to be dropping for you.

> again, most of the stats was gathered with netstat, since this is the
> easiest way I know to see things happening..

I really do appreciate the attention you are giving this, Jean-Mark.

Sean

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