Can you run the attached script and run your testing again?
I think it might be the problem of your dual cores balance the
interrupts on your testing NIC.
As we do a lot of things with SACK, cache misses and etc. might affect
your performance.

In default setting, I disabled tcp segment offload and did a smp
affinity setting to CPU 0.
Please change "INF" to your interface name and let us know the results.

Sangtae


On Fri, Apr 4, 2008 at 6:14 PM, Wenji Wu <wenji@fnal.gov> wrote:
quoted text
>
> >...Assuming it wasn't disabled already. If you find that there's
> >significant difference, you could try also with SACK+basic FRTO (set
> >the tcp_frto sysctl to 1).
>
> No, still the same. I tried tcp_frto with 0, 1, 2.
>
> SACK On is worse than SACK off.
>
> wenji
>
>
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