Xeon 2.8GHz DP & 2.0GHz MP - Part I: Taking over the Enterprise

Final Words

Just recently we showed the benefits of Hyper-Threading on the desktop but it is clear that the true potential of Intel's new technology is fully realized in the server market.

While unable to replace the power of additional CPUs, Hyper-Threading provides no less than a 30% boost in I/O loaded situations, which occurs quite often in reality. In fact, once you factor in the latency introduced by traffic flowing over the network before getting to the server there are quite a few opportunities for Hyper-Threading to fill those moments of idle execution.

However, for lightly loaded servers that don't experience much I/O utilization there may actually be a small performance drop if Hyper-Threading is enabled. In any situation where CPU performance is a key issue, enabling Hyper-Threading does seem to provide a performance gain. We can attribute this to an updated revision of the Hyper-Threading architecture in the new Xeons as well as the faster clock speeds that these processors are running at.

Needless to say, that if developers can come even remotely close to implementing this sort of thread level parallelism in desktop applications then Hyper-Threading will bring the Pentium 4 much more success than any other single architectural improvement.

Intel's new 533MHz FSB Xeon DPs perform quite well at their new 2.80GHz clock speed. As our tests have shown, the increased clock speed provides performance that's equal to if not greater than a Xeon MP system with an identical number of CPUs; the performance advantage only tilts in favor of the Xeon MP once you move to 4 processors.

We can also conclude that Intel's decision to make the Xeon DPs limited to 2-way configurations is solely to prevent cannabalizing 4-way Xeon MP sales. There are indeed many situations that would benefit from having a cheaper 4-way configuration of 2.8GHz CPUs but without any on-die L3 cache. This isn't to discount the power of the 108 million transistor Xeon MPs, but they are definitely not the most economical solution for enterprise customers and in many cases a 4-way Xeon DP configuration (if one existed) would suffice.

What is very interesting to note is the impressive scalability we saw when going from 2 to 4 processors, despite the fact that Intel's implements a shared bus architecture with the Xeon. Even though all 4 CPUs are sharing the same 3.2GB/s of FSB bandwidth, they are able to outperform a similarly configured 2-way setup by up to 88% in heavily loaded situations. Keeping this in mind, we are curious to see if AMD's Opteron architecture improves 4-way scalability even more or if it is unlikely that even this much load would saturate the Xeon's FSB.

That concludes part I of our Xeon DP & MP coverage, next we will be taking a look at the web server performance of these platforms. Be sure to check back after Comdex for part II...