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AMD touts ‘TDP Power Cap’ for forthcoming chips

Jun 28, 2011 — by LinuxDevices Staff — from the LinuxDevices Archive — views

In its upcoming “Interlagos” and “Valencia” Opteron chips for servers, AMD will offer a feature called TDP Power Cap. The technology, designed to let users reduce power usage while minimizing the performance consequences, could find a home in future AMD-powered embedded devices too.

Advanced Micro Devices for the past several years has been able to work with some of its largest users to create customized Opteron chips to meet their performance and power needs. They're the companies with massive data centers and tens of thousands of servers — who need as much performance as they can get while maintaining high-density and lower-power costs, according to Brent Kerby, senior product marketing manager for servers with AMD.

"A lot of the big cloud guys, the big mega-data center types, are focused specifically on meeting the demands of their parallel workloads," Kerby said in an interview with eWEEK, but declined to name the customers.

AMD engineers have put "knobs" into the Opteron BIOS over the years that can be manipulated to meet specific performance and power demands. But until now, such customization has been reserved for these large customers that buy thousands or tens of thousands of AMD-powered servers at a time.

However, with the upcoming 16-core "Interlagos" and eight-core "Valencia" Opteron chips based on the "Bulldozer" core, AMD is looking to give mainstream customers greater control over the performance and power consumption of their processors, according to Kerby.

With the new Bulldozer-based Opterons, which are set for release in the third quarter, AMD is introducing TDP Power Cap, which will give enterprises the ability to set the TDP (thermal design power) of their processors, essentially customizing their chips to meet power and workload demands.

Using various knobs in the BIOS, businesses will be able to reduce the overall TDP of the chip — they won't be able to increase it beyond the maximum level set by AMD — which will help in power consumption. Then, they'll also be able to tweak the frequency of the cores as needed to get the maximum amount of performance allowed under the TDP setting, according to Kerby.

"While you set the [TDP] cap, you can still operate at a high frequency," he said.

In other words, businesses can keep the TDP at the level set by AMD, and change the frequencies of the processors to add power, while keeping the overall power use under the TDP.

For high-density, highly bladed data center environments, such as cloud computing and Web serving, such capabilities can be key in keeping the power consumption down while maximizing the performance of the systems, Kerby said.

Being able to lower the TDP of a chip can result in an enterprise being able to add more blade systems to a rack, and do so without significantly reducing performance.

The TDP Power Cap feature improves on AMD's existing PowerCap Manager feature, which similarly lets managers cap the power consumption of a processor in its p-state (or operational state). PowerCap Manager can help improve energy efficiency but comes with a performance hit as well, John Fruehe, director of product marketing for server, embedded and FireStream products at AMD, said in an interview with eWEEK.

Nathan Brookwood, principal analyst at Insight 64, said AMD's TDP Power Cap technology could be a benefit for data center managers looking to squeeze more performance out of their infrastructures while keeping the power consumption down. The technology gives them "the ability to customize their processor and at the same time not sacrifice all the performance," Brookwood told eWEEK.

Whether it will give users reason to choose Opterons over Intel's Xeons comes down to a key metric, he added.

"Ultimately it will depend on the performance-per-watt in the Bulldozer versus the performance-per-watt in [Intel's] 'Westmere' and 'Sandy Bridge,' [Xeons]," Brookwood said. "Performance-per-watt is what people are always going to look at."

An enhanced Turbo Core, too

Along with TDP Power Cap, AMD in the Bulldozer-based Opterons will introduce an enhanced version of Turbo Core, a technology that was first launched last year in AMD's Phenom chips and that essentially enables users to push the chip's base speed up closer to the level of the TDP. The feature enables users to squeeze extra performance out of the chip and gain maximum clock speeds, and will complement TDP Power Cap in the area of customization, according to AMD.

APML (Advanced Platform Management Link), which allows for remote power management, also will work with TDP Power Cap, according to AMD's Kerby. Once the TDP limit is set, the APML software will determine the power budget and manage the power usage, including pushing power to specific cores when needed to keep use below the TDP setting.

AMD officials have been talking power efficiency since the first Opterons were rolled out almost a decade ago. Over the years, the vendor has added a host of power-management technologies, including PowerCap Manager, PowerNow, Dual Dynamic Power Management and CoolCore.

All these technologies — including TDP Power Cap — will help AMD in its efforts to court the large cloud and Internet businesses, which are trying to cram as much performance into their facilities as possible without ramping up the power consumption, Insight 64's Brookwood said.

"These days, more and more, it comes down to performance-per-watt," he said. "In these Internet-scale data centers, where there are thousands or tens of thousands of servers, these guys are extremely sensitive to performance-per-watt. So anything that you can do in this area will go a long way to making them like your product."

Not only is larger rival Intel also making inroads in driving down power consumption while increasing performance, but mobile chip designer ARM Holdings and many of its partners — including Nvidia, Marvell Technologies and Calxeda — are looking to move their highly energy-efficient chip designs up into the data center, for servers aimed at such environments as web serving and cloud computing.

Others also are looking at that sector, including Tilera, which is rolling out its own low-power, multi-core designs.

Jeffrey Burt is a writer for eWEEK.

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