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Date:      Wed, 24 Dec 1997 09:49:29 -0500
From:      dh2@netwalk.com
To:        Kapil Chowksey <kchowksey@hss.hns.com>
Cc:        hackers@FreeBSD.ORG
Subject:   Re: (?) lnc0: Transmit underflow error -- Resetting
Message-ID:  <19971224094929.26472@netwalk.com>
In-Reply-To: <199712241526.KAA17065@tarang.hss.hns.com>; from Kapil Chowksey on Wed, Dec 24, 1997 at 10:26:26AM -0500
References:  <19971223230921.57532@netwalk.com> <199712241526.KAA17065@tarang.hss.hns.com>

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Kapil Chowksey:
> On Tue, 23 December, dh2@netwalk.com wrote:
> > I'm trying to do transfers of a large amount of data between my FreeBSD
> > 3.0-971208-SNAP box with a NE2100 Lance card and a Linux 2.0.32 box with an
> > NE2000.
> > 
> > My effective transfer rate is measely 1.6kbytes per second over a 10Mbps
> > ethernet with FTP, and I'm getting loads of these in the FreeBSD error log:
> 
> Ditto here. I have a PCI based NE2100 card (lnc1) on an HP Vectra
> pentium 200Mhz class PC which gives equally pathetic performance (both
> under 2.2.5-RELEASE and 3.0-971208-SNAP) while ftp'ing to any other
> host (Solaris, HPUX, EtherExpress Linux's, ed0 based FreeBSDs).
> 
> It seems that packet sizes greater than 738 get delayed by 1-2 seconds
> in the driver itself !

That's interesting.  I found last night that if I cranked the lnc0 interface's
MTU down to 512, I got slightly better performance, but going even further 
down to 256 made a much bigger difference.

For example, FTPing a 540Meg file between the machines, at MTU=512, it was
still going to take > 100min to ftp it over a 10-base ethernet.  At MTU=256
however, it took only 15 min, just a few minutes longer than I'd expect at
an optimized config.

It appears that segment size is related as you said.  Though indications
here are that there's a significant difference with numbers below 738 --
between 256 and 512 for sure.

> I am not getting any messages from lnc driver however. Is there a
> maintainer for lnc driver currently ?

I'd also be interested.  Would be happy to try suggestions and patches here.

Thanks,

Randall Hopper




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