Power, Performance at the Core of Future Intel ChipsBy John G. Spooner | Print
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Intel's forthcoming chips will use less power but offer more performance, thanks to a new microarchitecture.SAN FRANCISCOAttention to power consumption has formed the core of a new generation of Intel chips coming out later this year.
Justin Rattner, Intel's chief financial officer, kicked off the company's spring Developer Forum here March 7 by taking the wraps off some of the features behind the chip maker's Core Microarchitecture. Core Microarchitecture, otherwise known as Next Generation Microarchitecture, is a redesign of the circuitry that underpins Intel's entire chip line. It not only delivers double-digit performance gains across desktops, notebooks and servers, but it will also help deliver double-digit cuts in power consumption, Rattner said. Intel first discussed it last August.
The main focus of the new architecture is cutting power consumptiona growing worry among businesses whose data centers are straining under increases in demand for electricity and cooling from deploying larger numbers of x86 servers and whose road warriors demand light laptops with longer battery lifewhile also increasing performance. Thus, the new architecture is, in some ways, paradoxical. Typically, bumping performance also involves making sacrifices in power.
Using Detroit as an analogy, car makers can deliver models that offer tremendous acceleration and top speeds, but which use lots of gasoline, or cars that offer tremendous range, but whose performance is less exciting, Rattner said. However, Intel claims to have turned that formula on its ear with the new architectures.
"Core combines energy efficiency with the same features that are expected in top-of-the-line microprocessors" such as virtualization, Rattner said. "Together, they deliver outstanding performance not just in mobile platform, where the technology originated, but across the entire range."
Thus, the first of three new Core Microarchitecture chipsMerom, Conroe and Woodcrest, dual-core chips for notebooks, desktops and servers, respectively, all of which are due later this yearwill offer 20 to 40 percent increases in performance while cutting desktop and server power. Merom, for its part, offers a performance increase while holding the line on power.
Merom will offer a 20 percent performance boost versus today's Core Duo processors while operating within the same power envelope, Rattner said.
Conroe, a desktop chip due in the third quarter, will deliver a 40 percent improvement in performance with a 40 percent reduction in power. It will offer a 65-watt thermal design power measurement, Intel officials said.
Woodcrest, which will be of particular interest to IT managers, offers an 80 percent performance improvement, along with a 35 percent reduction in power relative to Intel's current Xeon DP 2.8GHz dual-core chip for dual-processor servers, Rattner said.
Among the key elements of the architectureand the heart of the reason Intel says it can deliver performance gains while cutting powerare features such as its ability to executive four instructions in a single clock.
"That has given us the ability to get more done in fewer cycles. By doing so we consume less power," Rattner said.
The Core Microarchitecture uses a 14-stage pipeline, a sort of assembly line for instructions that breaks them down in order to act on them in parallel, in addition to a more advanced cache that features improved access times, meaning processor cores aren't waiting for data.
Pipeline length is an important element for chip performance and power. A longer pipeline allows a chip to hit higher clock speedsalthough clock speed brings increases in power consumptionbut performance gains don't always ensue. Longer pipeline chips take longer to recover from errors in later stages, something analysts call the pipeline tax.
Thus, chip makers must arrive at a balance. The Core Microarchitecture's 14-stage pipeline is slightly longer than that of some chips, such as the Core Duo, which has 12. But it's about half that of the Pentium 4, later versions of which had 31 stages. The Pentium 4, meanwhile, employed a complicated scheme that allowed it to process between one and three instructions per clock cycle.
Next Page: Other Core Microarchitecture features.
Several other new Core Microarchitecture features act to speed up the processing of Intel's SSE multimedia add-on instructions, consolidate multiple smaller instructions to run them as one and to increase the efficiency of accessing system memory, Rattner said.
Meanwhile, the company also employed some other design tricks, including one called power gating, which will down parts of a chip that are not needed at a particular instance to save power.
Although chips based on the new Core Microarchitecture are still several months away, at least on industry watcher says Intel's heading in the right direction with its new architecture.
"I've been extremely impressed with the work that's going on in the new Core architecture," said Kevin Krewell, editor in chief of the Microprocessor Report, following the Rattner keynote.
It's not a derivative of Yonah, the code name for Intel's current Core processor family for notebooks. Intel's current Core Solo and Core Duo notebook chips are not based on Core Architecture, however, at the moment.
Aside from the cache design, "this is a completely redesigned core," Krewell said. "It's almost as substantial a change as going from the Pentium III to the Pentium 4."
Intel has done its "homework in fine-tuning and crafting every aspect of the chip to increase performance .while in some cases lowering the power."
Aside from delivering new chips, Intel is also working on platform-level work to help cut the power consumption of hardware that surrounds its chips, Rattner said. It's also working with software developers to create multithreaded applications that can better take advantage of multicore chips.
Intel will move from dual-core or two-processor-inside-one-chip designs to quad-core chips in 2007.
"The potential for managing power at the platform is great, and it's something we need to take the opportunity to improve in all of our systems," he said.
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