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MPI newbie: Building MPI applications

October 12, 2013 at 7:30 am PST

In a previous post, I gave some (very) general requirements for how to setup / install an MPI installation.

This is post #2 in the series: now that you’ve got a shiny new computational cluster, and you’ve got one or more MPI implementations installed, I’ll talk about how to build, compile, and link applications that use MPI.

To be clear: MPI implementations are middleware — they do not do anything remarkable by themselves.  MPI implementations are generally only useful when you have an application that uses the MPI middleware to do something interesting.

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EuroMPI’13 Cisco slides: Open MPI Process Affinity User Interface

September 18, 2013 at 5:17 am PST

The slides below are from my presentation at EuroMPI’13 about Open MPI’s flexible process affinity interface (in OMPI 1.7.2 and later).  I described this system in a prior blog entries (one, two, three), but many people keep asking me about it.

Josh Hursey from U. Wisconsin, LaCrosse, wrote this IMUDI paper about the interface (IMUDI is a sub-workshop of EuroMPI focusing on end-user issues) to get a little more publicity and awareness of this process affinity system.  Specifically, we designed this affinity system so that we could get feedback from real end users about what is useful and what is not.

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EuroMPI’13 Cisco slides: UCS, Nexus, usNIC

September 17, 2013 at 5:22 am PST

A few people asked me to post the slides that I just presented in the Cisco vendor session at EuroMPI’13.  In short, I gave a brief overview of our servers and switches, and then some technical details of how we use SR-IOV in our usNIC, etc.

Here’s the slides: Read More »

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usNIC released!

I’m excited to announce that Cisco has just released usNIC as a feature of the UCS C-Series Rack Servers product line.

usNIC is available since the release 1.5(2) of the Cisco UCS C-Series Integrated Management Controller.

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Why is SR-IOV relevant in the HPC world ?

One feature of the usNIC ultra-low latency Ethernet solution for the UCS Cisco VIC that we think is interesting is the fact that it is based on SR-IOV.

What is SR-IOV, and why is it relevant in the HPC world?

SR-IOV (Single Root I/O Virtualization) is commonly used in the server virtualization world. The most commonly described purpose of SR-IOV in the hypervisor world is to allow a device partition, called VF (Virtual Function), to be mapped in the guest operating system address space. This allows the guest operating system to enjoy higher I/O performance and lower CPU utilization as compared to the alternative: software-emulated devices that are traditionally implemented in hypervisors.

Compared to the old world before hypervisors came along, that use of SR-IOV seems to allow to regain back some performance lost due to the hypervisor software intervention in the I/O data path. But why should I care about SR-IOV in the world of my network-latency-bound HPC applications running on common operating systems on bare metal servers?

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