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From: Richard L. Graham (rlgraham_at_[hidden])
Date: 2006-08-29 09:15:38


Remember that the kernel uses a fair amount of cpu time in the case
of TCP,
and the network portion of the transfer (where you would gain in
parallelism)
is relatively small. One sees most of the advantages of network
parallelism,
with respect to performance, when the on-host network protocol is low
relative
to the network processing, which at this stage is mostly with OS
bypass type
protocols...

Rich

On Aug 22, 2006, at 9:00 AM, Jayanta Roy wrote:

> Hi Galen,
>
> The GigE is on the ESB2. This lives on a 4GB/sec link to the MCH.
> I believe we aren't really running close to the I/O bandwidth limit.
>
> This MPI transfer uses both the ports as there are increment in RX
> and TX bytes
> of both eth0 and eth1. But I am getting the same bandwidth with or
> without
> using "--mca btl_tcp_if_include eth0" in the mpirun command line.
> Are we
> missing something? Or I have to go for linux ethernet channel bonding?
>
> Regards,
> Jayanta
>
> On Tue, 22 Aug 2006, Galen M. Shipman 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
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> ~~~~
>>> _______________________________________________
>>> users mailing list
>>> users_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>
>>>
>>
>> _______________________________________________
>> users mailing list
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>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ~~
> 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
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ~~
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users