Cisco Blogs

Cisco Blog > High Performance Computing Networking

Short message latency and NUMA effects

I’ve previously written a bunch about the effects of location, Location, LOCATION! on MPI applications.

Here’s another subtle NUMA effect that a well-tuned MPI implementation can hide from you: intelligently distributing traffic between multiple network interfaces.

Yeah, yeah, most MPI implementations have had so-called “multi-rail” support for a long time (i.e., using multiple network interfaces for MPI traffic).  But there’s more to it than that.

Read More »

Tags: , , , , ,

Ultra low latency Ethernet (UCS “usNIC”): questions and answers

I have previously written a few details about our upcoming ultra low latency solution for High Performance Computing (HPC).  Since my last blog post, a few of you sent me emails asking for more technical details about it.

So let’s just put it all out there.

Read More »

Tags: , , , , ,

Open MPI and the MPI-3 MPI_T interface

Open MPI recently revamped its entire run-time parameter system (a.k.a., “MCA parameter system”) as part of its implementation effort for the “MPI_T” interface from MPI-3.

The MPI_T interface is a standardized interface designed for MPI tools, but can be used by regular MPI application programs, too.

Specifically, MPI_T provides programatic access to two types of MPI implementation data:

  1. Control variables: used to control the behavior of an MPI implementation
  2. Performance variables: provide access to internal MPI implementation performance metrics

Read More »

Tags: , , ,

Cisco’s Philosophy on Open Source

Last weekend, I was fortunate enough to be able to attend the Midwest Open Source Software Conference (MOSSCon 2013).  I met some fascinating people, listened to some great talks, and learned a bunch of new things.

All in all, a win.

I also presented a talk on two things:

  1. The general open source philosophy at Cisco
  2. My specific open source work at Cisco

The slides that I presented are below (slightly edited from their original form; I used a few animations in my original slides, which don’t work on Slideshare):
Read More »

Tags: , , , , , ,

MPI and Java: redux

In a prior blog entry, I discussed how we are resurrecting a Java interface for MPI in the upcoming v1.7 release of Open MPI.

Some users have already experimented with this interface and found it lacking, in at least two ways:

  1. Creating datatypes of multi-dimensional arrays doesn’t work because of how Java handles them internally
  2. The interface only supports a subset of MPI-1.1 functions

These are completely valid criticisms.  And I’m incredibly thankful to the Open MPI user community for taking the time to kick the tires on this interface and give us valid feedback.

Read More »

Tags: , , ,