Open MPI logo

Open MPI User's 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.

Subject: Re: [OMPI users] TCP Latency
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-07-28 14:59:51


On Jul 28, 2008, at 2:53 PM, Andy Georgi wrote:

> we use Chelsio S320E-CXA adapters (http://www.chelsio.com/assetlibrary/products/S320E%20Product%20Brief%20080424.pdf
> ) in one of our clusters. After tuning the kernel i measured the
> ping pong latency via NetPIPE and got ~12us which is pretty good for
> TCP i think. So i wrote a simple ping-pong-kernel and was really
> terrified about the ~45us i got with OpenMPI 1.2.6. Are there any
> hints how we can reduce the MPI latency? To increase the bandwidth
> we already set the buffer sizes but we couldn't find a parameter
> which can be relevant for the latency. Every hint is welcome.

The upcoming Open MPI v1.3 series will support iWARP, which gives much
better latency than that. I don't know all the Chelsio models
offhand; are those iWARP-capable cards?

-- 
Jeff Squyres
Cisco Systems