The great 64-bit shootout

To paraphrase Benjamin Disraeli, there are lies, damn lies, and benchmarks. Synthetic CPU tests can provide numbers pointing one way or the other and can help unmask weaknesses and strengths in chip architectures, but what matters most is how the processors perform in production.

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Last month, I used real-world, application-based benchmarks to test a Dell PowerEdge server sporting the spanking new Xeon with EM64T (Extended Memory 64 Technology), otherwise known as Intel’s answer to AMD’s Opteron. But the Intel processor was so fresh, we had to stick with 32-bit benchmarks and postpone tests of the chip’s 64-bit x86 capabilities, which are based on, but not identical to, the AMD’s x86-64 standard.

Well, the wait is over. We’ve polished our 64-bit, app-based benchmarks for EM64T and let ’em rip. The results confirm what Test Center Technical Director Tom Yager asserted in early August: AMD has the first-mover advantage in the x86-64 space, and Intel has some catching up to do. Whereas the EM64T Xeon is no slouch, the Opteron reigns supreme.

Battleof the 64-bit engines

I settled on some simple, real-world benchmarks to meet the goal of measuring production performance. And because the objective was to compare the 64-bit performance of the two processors, only 64-bit code was used throughout.

I made every effort to maintain as much similarity as possible between the test systems. In Intel’s corner, I tested a Dell PowerEdge 2800 with dual 3.6GHz Xeon EM64T CPUs, 4GB of RAM, and 36GB U320 SCSI drives. On the AMD side, I tested a Newisys 2100 with dual 2.4Ghz Opteron 250 CPUs, 4GB of RAM, and 36GB U320 SCSI drives. The client generation system used for the external tests was a Compaq ProLiant ML370 running Red Hat AS 3.0 with two 32-bit, 2.8GHz Xeon processors and 4GB of RAM. All systems were connected via gigabit copper on a flat network.

Linux was the obvious operating system choice for both the Xeon EM64T and Opteron systems. Although Microsoft has yet to ship a 64-bit server platform, Linux has been there for years. On both systems, the base distribution was Red Hat Advanced Server 3.0, running the latest Red Hat kernel, 2.4.21-15.EL. Red Hat’s AS 3.0 U3 for x86-64 was installed and updated with all updates available at the time of the tests.

The benchmarks themselves included MySQL 3.23.58 performance tests run with MySQL’s sql-bench tool, static and dynamic Web serving via Apache 2.0.46. In a nod to those concerned with HPC performance, I also ran Linpack benchmarks via HPL (High Performance Linpack).

The test results were conclusive. In every real-world test, the Opteron 250-based Newisys server bested the EM64T Xeon server, despite the fact that the latter had a faster clock speed. For years, Intel has emphasized clock speed, implying that a 3.6GHz CPU will best a 2.4Ghz CPU without fail. In these tests, the 2.4Ghz Opteron system beat the 3.6Ghz EM64T Xeon system across the board. Clock, it seems, isn’t everything.