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From: Durga Choudhury (dpchoudh_at_[hidden])
Date: 2006-08-22 10:29:15


I am also guessing you might be actually using only one of the gigabit links
even though you have two available. I assume you have configured the
equal-cost-multi-path (ECMP) IP routes between the two hosts correctly; even
then, ECMP, as implemented in most IP stacks (not sure if there is an RFC
for this), really works if you are reaching the same destination network but
two different hosts. For example, ECMP would use one link to reach
10.0.0.1and another to reach
10.0.0.2, both on the 10.0.0.0/24 network. In your case, there is only one
end host, so your IP stack might be actually using one link all the time.

Also, the bus might be a bottleneck as Galen pointed out

Thanks
Durga

On 8/22/06, Galen M. Shipman <gshipman_at_[hidden]> wrote:
>
> Jayanta,
>
> What is your bus on this machine? If it is PCI-X 133 you are going to be
> limited, also memory bandwidth could also be the bottleneck.
>
> Thanks,
>
> Galen
>
>
> Jayanta Roy wrote:
>
> >Hi,
> >
> >In between two nodes I have dual Gigabit ethernet full duplex links. I
> was
> >doing benchmarking using non-blocking MPI send and receive. But I am
> >getting only speed corresponds to one Gigabit ethernet full duplex link
> >(< 2Gbps). I have checked using ifconfig, this transfer is using both the
> >ports, then why I am not getting full throughput from dual Gigabit
> >ethernet ports? Can anyone please help me in this?
> >
> >Regards,
> >Jayanta
> >
> >
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >Jayanta Roy
> >National Centre for Radio Astrophysics | Phone : +91-20-25697107
> >Tata Institute of Fundamental Research | Fax : +91-20-25692149 Pune
> >University Campus, Pune 411 007 | e-mail : jroy_at_[hidden]
> >India
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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