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Date:      Wed, 24 Jan 2001 22:01:12 -0700
From:      "Kenneth D. Merry" <ken@kdm.org>
To:        Joong Hyun Kim <better@ns1.betterbox.net>
Cc:        hardware@FreeBSD.ORG
Subject:   Re: New Netgear Model GA620T gigabit cards installed, but slow speeds... any ideas?
Message-ID:  <20010124220112.B24460@panzer.kdm.org>
In-Reply-To: <EKEPIMFMEPAAELGAIDALMEPODJAA.better@ns1.betterbox.net>; from better@ns1.betterbox.net on Wed, Jan 24, 2001 at 10:57:33PM -0600
References:  <EKEPIMFMEPAAELGAIDALKEPJDJAA.better@ns1.betterbox.net> <EKEPIMFMEPAAELGAIDALMEPODJAA.better@ns1.betterbox.net>

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On Wed, Jan 24, 2001 at 22:57:33 -0600, Joong Hyun Kim wrote:
> Hi folks... I've found the problem.  The hardware does play a major role.
> Looks like today's 32bit pci bus is only capable of doing 300 to
> 400MBits/sec.  We had one box with Dual Xeon 500Mhz that was able to push
> close to 400MBits/sec... we've found this by using netpipe on it's own ti0
> interface.
> 
> The other machine only has Quad Pentium Pro 200Mhz machine... that's where
> the bottleneck showed about 80MBits/sec.
> 
> According to 3Com, 64Bit PCI bus can push the gigabit ethernet even further.
> We are now looking into replacing the Quad Pentium Pro server with new
> hardware. :-)

It isn't really the PCI bus that's the bottleneck in your case, but rather
the CPU.

Since the kernel can only run on one processor at a time, you're
effectively limited to one Pentium Pro 200's worth of bandwidth at any
given time.

I've gotten 760Mbps performance between two Pentium II 350's with Tigon
boards.  Both had 440BX chipsets and 32 bit PCI.  But that was with zero
copy TCP and checksum offloading.  See:

http://people.FreeBSD.org/~ken/zero_copy/

That said, using jumbo frames might increase the performance somewhat if
you haven't already tried it.

Ken
-- 
Kenneth Merry
ken@kdm.org


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