Editor's Note: A few months ago I published what could be described as a small case study on the ATA-133 interface. It was a very specific, very limited-scope, but detailed article designed to answer a very specific question. It was somewhat of a new venture for me personally, and I enjoyed writing it. The feedback I received was tremendous as well, so I decided to experiment with that type of article more often in the future. You are about to read my latest attempt -- as always, feedback is welcomed.
When technical details regarding Intel's Pentium 4 (then known only as Willamette) began to surface in the months before the launch, there was a growing level of concern regarding the processor's extremely deep pipeline, and the potential effect on IPC. When the processor debuted, those concerns were justified, as the Pentium 4 exhibited an uncharacteristically low IPC, even for an unseasoned architecture. Many were quick to condemn the Pentium 4 platform for that lack of performance, however others insisted that the Pentium 4 was not designed for today; rather it was designed for tomorrow.
The Pentium 4's 20-stage deep pipeline, while certainly having an adverse effect on IPC, would allow the core to scale to massive clock speeds, and to do so without heavy reliance on new process technologies. Certainly this has held true with respect to clock speed -- the Pentium 4, now at 2.2 GHz, has nearly doubled its introductory frequencies in just over a year. However, there was never very much doubt as to the platform's ability to scale in clock speeds. The real question mark, instead, is whether or not performance
has scaled along with clock speed. One of the biggest factors that will affect performance scaling is the ability of the memory subsystem to keep the bandwidth-hungry processor amply fed.
And thus, we arrived at the topic of today's article. We decided to take a look at just how well the performance of the Pentium 4 platform has scaled along with clock speed, from 1.4 GHz up to 2 GHz on current SDRAM and DDR platforms, as well as upcoming DDR platforms (DDR333). Before reading on, please note that this article is merely meant to be a small case study. We have a very specific question which we will be addressing in as much detail as possible, and we will remain within the very limited scope of that question. This article is not meant to be a comprehensive guide to the Pentium 4, nor is it meant to in any way compare the Pentium 4 to AMD's offerings. The intent here is merely to provide some information you might not have seen before, and hopefully to answer a few questions (and, we can only hope, create a few new ones as well).
To those of you who will undoubtedly read this article and ask "What’s the point?"; the point is curiosity.