Open MPI logo

Open MPI Development Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

From: Tim S. Woodall (twoodall_at_[hidden])
Date: 2005-11-29 12:36:26


George,

Can you try out the changes I just commited on the trunk? We were doing
more select/recvs then necessary.

Thanks,
Tim

George Bosilca wrote:
> I run Netpipe on 4 different clusters with differents OSes and Eternet
> devices. The results is that nearly the same behaviour happens all the
> time for small messages. Basically, our latency is really bad. Attached
> are 2 of the graphs on one MAC OS X cluster (wotan) and a Linux 2.6.10
> 32 bits one. The graph are for Netpipe compiled over tcp, and for Open
> MPI with all the PMLs (uniq, teg and ob1).Here is the global trend:
>
> - we are always slower than native TCP (what a guess!)
>
> - uniq is faster than teg by a fraction of second (it's more visible on
> fast networks).
>
> - teg and uniq are always better than ob1 in terms of latency.
>
> - the behaviour of ob1 differ on wotan and boba. On boba the
> performances are a lot closer to the other PML when on wotan it's like
> 40 micro-second slower (it nearly double the raw TCP latency).
>
> On the same nodes I run other Netpipe with SM and MX and the results are
> pretty good. So I think we have this latency problem only on TCP. I will
> take a look to see how exactly is happens but any help is welcome.
>
> george.
>
> "We must accept finite disappointment, but we must never lose infinite
> hope."
> Martin Luther King
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> devel mailing list
> devel_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/devel