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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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MPI newbie: Requirements and installation of an MPI

July 31, 2013 at 9:00 am PST

I often get questions from those who are just starting with MPI; they want to know common things such as:

  • How to install / setup an MPI implementation
  • How to compile their MPI applications
  • How to run their MPI applications
  • How to learn more about MPI

This will be the first blog entry of several that attempts to guide MPI newbies down the parallelization path.

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Short message latency and NUMA effects

July 23, 2013 at 5:00 am PST

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.

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How many network links do you have for MPI traffic?

July 19, 2013 at 5:00 am PST

If you’re a bargain basement HPC user, you might well scoff at the idea of having more than one network interface for your MPI traffic.

“I’ve got (insert your favorite high bandwidth network name here)! That’s plenty to serve all my cores! Why would I need more than that?”

I can think of (at least) three reasons off the top of my head.

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