Benchmarking Methods

Not only are we going to provide the benchmark numbers, we also provide the benchmark methods and techniques. How is that for service. Now you can run your own benchmarks.

From the What's Watts Dept.

Some Clarity around TDP ratings

Managing power usage on multi-core processors has become an important aspect with modern computing systems. At the same time, finding an accurate specification of actual power usage has become more difficult. Knowing power usage is important in many areas and particularly when considering the efficiency of High Performance Computing (HPC) systems. In almost all modern CPUs and GPUs the only number that seems to give a hint about power usage is Thermal Design Power or TDP.

According to Wikipedia Thermal Design Power is defined as follows:

... is the maximum amount of heat generated by a computer chip or component (often a CPU, GPU or system on a chip) that the cooling system in a computer is designed to dissipate under any workload.

Some sources state that the peak power rating for a microprocessor is usually 1.5 times the TDP rating

Can more cores per node address HPC needs or are thin nodes on the horizon?

As multi-core continues the dominate the x86 marketplace, there has always been a nagging question for some HPC users; What is better, many single socket multi-core nodes or fewer fat nodes with as many sockets as possible. Of course the amortization of hardware costs (power supplies, cases, hard disk, etc) is a win for the fat node approach, but what about performance? As nodes offer more and more cores, does HPC performance follow?

It is 10pm, do you know where your cores are?

Ever since multi-core processors hit the market I have always been interested in testing how well they actually work. Of course, there are application benchmarks, which are always a good measure, but I like to look at some basic properties of a new processor (I look at networking and storage in other tests). The compute testing I do is rather straightforward, yet I have seen very few of these types of results. In particular, most results are for Windows or involve "web benchmarks." Since I work in Linux High Performance Computing (Linux Clusters) sector, I thought some examples of how I evaluate multi-core may be of interest to others.

Assume Nothing, Test Everything

In a previous article, we learned how to test an interface with Netpipe. In terms of clusters, Netpipe can be considered a micro-benchmark as it only tests a single (but important) component of the cluster. Can we conclude that good Netpipe performance means we have a good cluster? Well, it depends, maybe we can and then again more testing may be needed. Let's consider the fact that Netpipe performance tells us about the maximum limits of TCP/IP performance between two nodes. When we run parallel applications, there is usually more involved than just raw TCP/IP performance. There is usually an MPI layer between your application and the TCP/IP layer. In addition, there are effects due to compilers and node hardware (i.e. dual vs. single) and even the application itself may stress the interconnect in way not measured by Netpipe. Tests that run over multiple comments are usually referred to as macro-benchmarks because they involve a "whole system test" vs a single component test. Both are valuable, but neither may tell the whole story, however.

Do you know about the Beowulf Performance Suite?

The Beowulf Performance Suite (BPS) was designed to provide a comprehensive and comparative way of measuring cluster performance. Although BPS contains many benchmarking programs, BPS is not designed to directly benchmark clusters. BPS is designed as an analysis tool to measure differences due to hardware or software changes on the same cluster. In addition, successfully running all the tests provides some assurances that the cluster is configured properly.

The suite can run any or all programs and produce HTML output files. The use of HTML makes it trivial to share your results with others on the web. The following tests are available:

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