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Date:      Wed, 04 Dec 2002 11:08:45 +0200
From:      ianf@za.uu.net
To:        Joshua Goodall <joshua@roughtrade.net>
Cc:        Brad Knowles <brad.knowles@skynet.be>, Craig Reyenga <creyenga@connectmail.carleton.ca>, Terry Lambert <tlambert2@mindspring.com>, freebsd-current@freebsd.org, Christopher J Olson <chriso@tamu.edu>
Subject:   Re: Any ideas at all about network problem? 
Message-ID:  <69354.1038992925@wcom.com>
In-Reply-To: Your message of "Wed, 04 Dec 2002 12:58:18 %2B1100." <20021204015818.GB54075@roughtrade.net> 
References:  <20021204015818.GB54075@roughtrade.net> 

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Joshua Goodall wrote:
> On Wed, Dec 04, 2002 at 01:32:58AM +0100, Brad Knowles wrote:
> > At 12:31 PM +0200 2002/12/03, ianf@za.uu.net wrote:
> > 
> > > The two machines involved are connected by a crossover cable:
> > 
> > 	I've heard of lots of problems with machines using cross-over 
> > cables.  Can you connect the machines through a switch, and ensure 
> > that they are hard-wired to 100Base-TX full duplex at both ends, as 
> > opposed to auto-negotiating?
> 
> Just to add to this a-la-carte selection of possibilities; I recently
> debugged a NIC throughput problem which was resolved by a flash BIOS
> upgrade.  This was an ASUS A7VL-VM motherboard, which appeared to do
> unpleasant things to PCI IRQs.

Wipes egg off face: it seems that most of the bottleneck was an old
drive in the one machine, although systat showed it as only 67%
busy.  If I fetch a file off the machine with the slow disk twice,
the second time it's served from cache and the transfer rate is
60.9 megabits per second (test file is 90984206 bytes).  The receiving
machine's disk is reported as 10% busy by systat.  Much better, but
I'd still expect the ethernet to be saturated since transferring
data to faster disk using the transaction size from systat yields
about 143 megabits per second.

[brane] ~ $ dd if=/dev/zero of=t bs=126k count=705
705+0 records in
705+0 records out
90961920 bytes transferred in 5.100551 secs (17833744 bytes/sec)

I'll try a long cable tonight and see if I can borrow a switch from
work for the evening.

Ian

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