Re: TCP performance on GBE LAN

From: Stephen Hemminger
Date: Thu Mar 03 2005 - 13:04:45 EST


On Thu, 3 Mar 2005 02:20:36 -0800 (PST)
sai narasimhamurthy <sai_narasi@xxxxxxxxx> wrote:

> Hi,
> I just do not understand why the throughputs indicated
> by IPERF on a GBE LAN is so very low!!! I am speaking
> of throughputs around 50-100 Mb/s!! I understand all
> the optimizations of jumbo frames(I have max'd it!)
> and large windows etc(which shouldnt actually matter
> in a LAN since the RTTs are so very low) . The two
> machines I am working on are not even 10 meters
> away!!!:))
>
> My iSCSI application is heavily hampered by TCP. I am
> working with the 2.6.10 kernel..(has any one faced low
> throughputs in a GBE with 2.6.10? let me know ) .
>
> I would be very happy to push the TCP throughput to
> around 600-700 Mb/s atleast. any suggestions?
>
> Thanks
> Sai

I get 800-900 Mbits/sec using iperf on 64 bit PCI hardware (E1000, skge, tg3).
Less on 32 bit PCI hardware because of bus limitations.
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