Intel Delves Deeper into 'Nehalem'

Intel is offering a chance to peek under the hood of its new "Nehalem" microarchitecture and get a glimpse at some of the technologies it's using, including its approach to saving power and transferring data from one chip to another.

At the VLSI Symposia held June 17 to June 20, Intel will present a new paper June 19 called "Next Generation Intel Micro-architecture (Nehalem) Clocking Architecture," which will offer an account of some of the new technologies and innovations going into this particular microarchitecture.

The first of the Nehalem processors for servers and high-end desktops will likely debut in the fourth quarter with more chips based on the architecture entering the market by the first half of 2009. The first of the Nehalem chips will include four processing cores.

In describing Intel's research paper, Rajesh Kumar, an Intel Fellow and director of Circuit and Low Power Technologies for the company, dwelt on two aspects of Nehalem: the integrated memory controller and a feature called QuickPath, which allows the processors to connect to another component or another chip on the motherboard.

"Here, the path to memory and the path to the chip are all integrated into the CPU itself," Kumar said during a briefing before the start of conference. "The reason we are doing this is to get much lower latency to memory and much higher bandwidth to memory. The numbers we are going to achieve with Nehalem are 25GB per second for socket-to-socket communication and 32GB per second for going to main memory."

Kumar added that this means Nehalem is about three times faster than other chips in the market. In this case, Intel is referring to Advanced Micro Devices' Opteron processors, which have used integrated memory controllers and high-speed interconnects for a number of years.

For years, Intel lagged behind AMD in these types of technologies, which allowed AMD to gain market share, especially for high-end multisocket servers where higher bandwidth is a must. Although it's too early to say for certain if Intel will catch up with AMD, the chip giant is certainly moving in that direction and its customers can expect more details later in 2008.

"I would say that this paper is the beginning of a rolling thunder campaign that will last at least through the end of this year and only let up once all of Intel's Nehalem processors have been launched," said John Spooner, an analyst with Technology Business Research. "During this time, the company is going to begin building the case for Nehalem to be the highest-performing x86 chip in history, with huge benefits in performance per watt for servers in particular. Intel is betting big on Nehalem and it wants the processor family to be well received. So it's working to begin building interest in the platform."

Since the Nehalem architecture will be used across an array of product segments—servers, desktops, notebooks—Kumar said Intel engineers had to consider how they could change the structure of the chips to fit within these different segments. They made the processing cores modular so the cores could be easily switched out to meet the needs of different products.

Intel also decoupled the main components, allowing the voltage and the clock frequencies of the different parts to be set independently of one another. This allows Intel to design chips off the same basic architecture that can offer energy efficiency for one product and high performance for another.

"The CPU core, for example, can be running at its own frequency and voltage while the memory system is running on its own and I/O is running on its own and each of them can be tuned for a different segment," Kumar said.

"This idea itself is not new, but the implementation is new," he added. "So far, most have tried to do this with asynchronous interfaces, which happen to be fairly slow … so the main innovation here is to do this in a synchronous fashion, which is very low latency and [offers] high performance."

Finally, Kumar said Nehalem will adjust to the type of applications a system is running and will adjust its frequency to the power it needs to run these different pieces of software.

Intel did not say what clock speeds the Nehalem chips will offer. The paper also did not detail the exact power envelope these processors will have, although Kumar noted that Nehalem gives Intel the ability to integrate a graphics core into the processor.

Intel is expected to give full details about Nehalem at its Developer Forum in August.