Before we pass over to discussing the results of our tests, I would like to say a few words about the marking we are going to use on our diagrams hereinafter. Even though we actually tested AMD Opteron 875 processors, we will mark the results of our workstation in the “correct terms”. In other words, we will call it “Dual Opteron 275” The performance results shown by our workstation platform with a single processor installed will be marked as “Single Opteron 175”.
We decided to start our test session with a popular PCMark05 from Futuremark. Although we cannot regard it as a professional application, it will still be very interesting to take a look at the dual-processor system performance there. Especially, since this benchmark has some scenarios running four parallel threads at a time. And this is exactly what we need to load our workstation based on two dual-core CPUs to the full extent.
As we have expected, the processor test shows the indisputable advantage of the dual-processor system over the single-processor one. The workstation with two Opteron 275 processors outperforms the same platform with only one Opteron 175 processor by about 25%. As a result, it proves the fastest system of all testing participants in PCMark05.
In fact, we should also point out the high result demonstrated by the Pentium Extreme Edition 840 based platform in this test. This CPU can also process four computational threads at a time as it contains two processor cores, each supporting virtual multi-core technology – Hyper-Threading.
The memory test from the same PCMark05 benchmarking set reveals a rather strange result, I should say. As we can see our dual-processor workstation based on dual-core Opteron CPUs runs quite low. It wouldn’t be surprising at all, if it didn’t support NUMA technology, because the Registered memory modules are initially slower than their unbuffered fellows. However, in this case the dual-processor system has four memory access channels, and should theoretically be at least as fast as the same single-processor platform.
However, there appears to be a pretty logical explanation to this seemingly strange behavior of our Dual Opteron 275. Only if you address the memory in two independent threads, you can really benefit from the NUMA technology. The PCMark05 memory test is single-threaded, that is why it is not really representative of what the memory subsystem of our dual-processor Opteron workstation is capable of.