Lies, Damned Lies, And Statistics . . . And Benchmarks

I have been working on a research document, to be published this quarter, on the impact of 8-socket x86 servers based on Intel’s new Xeon 7500 CPU. In a nutshell, these systems have the performance of the best-of-breed RISC/UNIX systems of three years ago, at a substantially better price, and their overall performance improvement trajectory has been steeper than competing technologies for the past decade.

This is probably not shocking news and is not the subject of this current post, although I would encourage you to read it when it is finally published. During the course of researching this document I spent time trying to prove or disprove my thesis that x86 system performance solidly overlapped that of RISC/UNIX with available benchmark results. The process highlighted for me the limitations of using standardized benchmarks for performance comparisons. There are now so many benchmarks available that system vendors are only performing each benchmark on selected subsets of their product lines, if at all. Additionally, most benchmarks suffer from several common flaws:

  • They are results from high-end configurations, in many cases far beyond the norm for any normal use cases, but results cannot be interpolated to smaller, more realistic configurations.
  • They are often the result of teams of very smart experts tuning the system configurations, application and system software parameters for optimal results. For a large benchmark such as SAP or TPC, it is probably reasonable to assume that there are over 1,000 variables involved in the tuning effort. This makes the results very much like EPA mileage figures — the consumer is guaranteed not to exceed these numbers.
Read more