AMD lucks out on server benchmarks

The new benchmarks for AMD’s many cored server chips are out and they make disappointing reading for those who hoped that it would rally the outfit from a rash of gloomy news.

After Bulldozer was greeted by a big yawn, there was some hope that server benchmarks would redeem the chip and give AMD something to bash Intel with.

However it is starting to look like the 6200 Opterons (Interlagos) are only slightly better than their predecessor.

According to Hot Hardware, the new chips are a sidewise move from the older 6100 series, which is based on Magny-Cours.

Interlagos has the same problems which have crippled Bulldozer. A shared core design hurts SMP scaling which means that a a 16-core Interlagos scales more like a 13-14 core Magny-Cours.

While the clock speeds are better these are offset by Bulldozer’s lower single-thread performance. It also draws more power than its predecessor, which in turn prevents further clock speed scaling.

According to Ars Technica,  Interlagos is faster than its predecessor in some tests, but not by much.

In JBB2005, Interlagos is just 27 percent faster than Magny-Cours, despite 33 percent additional cores and a four percent clock speed advantage.

Part of he problem was that MD compromised single-threaded performance in order to allow Bulldozer to run more threads concurrently, and that trade-off simply hasn’t been worth it.

Ars said that it wondered what might have happened if AMD had simply extended its old architecture. Another four cores in a Magny-Cours processor would show close to the same 33 percent gain, and would do so without compromising single-threaded performance.

Bulldozer/Interlagos was supposed to save die space compared to Magny-Cours, but AMD just loaded the chip with 16MB of L2+L3 cache per eight-core configuration which made the space savings redundant.

So far, then, it looks like AMD is losing the technology war to Intel.