Behind AnandTech - The Search for the Perfect Servers

Athlons as servers?

A while ago we had the idea of doing a web server benchmark comparison, both for our own information and to include in an upcoming article. This was shortly after the release of AMD's Athlon processor last year, and as you can probably guess, the article never made it to publications. But the benchmarks were actually done and ready to go.

Our Senior Developer, Jason Clark, put together some custom tests that measured the performance of the processors in the scenario they would be put in if they were running in AnandTech Web Servers. It turns out that in these tests, the AMD Athlon 600 (512KB L2 cache running at 300MHz) was approximately 10% faster than the Pentium III 600 (512KB L2 cache running at 300MHz).

The release of the Coppermine with its on-die, full speed 256KB L2 cache would most likely cut down on that lead or even switch the possession of the top performer award, however we never continued the benchmarks with the Coppermine because the article never made it to publication.

We attributed a large amount of the Athlon's success to the fact that it has such a large L1 cache, but as its clock speed increased we were afraid that the slower L2 cache could become a performance hindrance if it were ever to be used in a server environment.

Now that the Athlon has a full speed 256KB L2 cache, in addition to its already large 128KB L1 cache, the processor is actually a perfect candidate for a Web Server; and as we mentioned earlier, you don't necessarily want to have a single dual processor web server, rather two single processor servers, so the current lack of any multiprocessor capable Athlon chipsets wasn't a problem.

The Athlon's effective 200MHz EV6 bus wouldn't be a bottleneck at all, whereas the 100MHz FSB we'd be forced to use on the BX chipset would cause a performance limitation, and the KT133 chipset supports a 133MHz memory bus which was just what we were looking for. Remember, in an ideal setup you want the content you're serving from your web server to come entirely from cache & system memory, so a fast path to the memory is a definite prerequisite.

The only question that remained was, would any of the currently available Socket-A motherboards stand the test of being used as a server platform with all three DIMM slots populated with 256MB modules? While we had done testing to ensure 256MB module compatibility and stability with all DIMM slots populated, we had never done the type of stress testing that would be necessary to simulate the load these boxes would be under as servers.