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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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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.

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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.

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Why MPI is Good for You (part 3)

I’ve previously posted on “Why MPI is Good for You” (blog tag: why-mpi-is-good-for-you).  The short version is that it hides the typical application programmer from lots and lots of underlying network stuff; stuff that they really, really don’t want to be involved in.

Here’s another case study…

Cisco’s upcoming ultra-low latency MPI transport is implemented over an “unreliable” transport: raw Ethernet L2 frames. For latency reasons, it’s using the OpenFabrics verbs operating-system bypass API. These two facts mean that a) userspace is directly talking to the NIC hardware, and b) we don’t have a driver thread running down in the kernel that can service incoming frames regardless of what the MPI application is doing.

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