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Advanced Micro Devices Inc.s announcement that its new PowerNow technology will be available on its Opteron line of processors could mean a lot to some enterprise customers.
The technology, which actually became available in May, despite AMDs announcement this week, is designed to let the processor run more slowly when demand is light, and then to return to full speed when needed. The technology is the same as the companys “Cool and Quiet” technology intended for laptop applications.
For AMD customers this technology could be crucial. “We have a lot of our customers in the server world who are really facing a lot of power infrastructure issues,” said Margaret Lewis, AMDs commercial software strategist. According to Lewis, customers are finding that they cant provide more power to their data centers than they already have, and they cant provide more cooling, either. She said that the best they can do is make judicious use of the power they have.
“Hotter processors take more power, and they require more power to cool,” Lewis said. She added that in many cases, data center constraints mean they cant have more power, and even those enterprises that can add more would rather not do it. By slowing the processor down when its not working hard, the power requirement is reduced, and the resulting heat generation is reduced.
While the PowerNow technology has been built into Opteron processors produced since May, machines with these processors need a BIOS update from AMD to make it work. And, of course their operating system needs to support PowerNow. To date, according to Lewis, there are two operating systems that have support, with another on the way: SuSE Linux Version 9 for the desktop and server, and Microsoft Windows XP with Service Pack 2. Still to come is Windows 2003 Server, which will support PowerNow when Service Pack 1 arrives. Lewis said that support for PowerNow is available in the Linux kernel, but most distributions have yet to include it. She said that Red Hat Linux should include the capability soon.
Part of a Trend
“This is definitely a trend,” says Kevin Krewell, editor in chief of the Microprocessor Report. “Intel [Corp.] has signaled that theyre putting power management into the next generation of Itanium,” Krewell said, adding that this is “not a new concept.” He noted that Intel processors designed for the mobile market have had a similar technology for years.
Krewell said that theres the possibility that the time required to ramp up the processor speed when theres an increase in demand could add latency to the server. “There could be some lag if the processor is fairly idle and then theres a surge of traffic,” he said.
He noted that while it might be possible to measure such latency, it wouldnt be a problem to users of a server because it would affect only the first access attempt and then only by a few milliseconds. “The overall impact on system performance is negligible.” Krewell said. “Anybody running data centers with lots of processors that arent all under full demand at the same time” will benefit from this technology, Krewell said, adding that this is a “pretty typical” scenario.
Krewell said that while companies with fully committed data centers would benefit the most from this technology, he thinks that nearly any company will choose it, or Intels version of the same thing, if only because it will save money on power and cooling. He also said that such technology would make an even greater difference in blade servers with their even-higher density.
Lewis said that, to date, AMD hasnt seen any adverse performance effects from the PowerNow technology. She said tests have shown that processors perform just as well with it enabled, and even running benchmarks flat-out shows a decrease in power consumption of about 3 percent. “We can reduce power usage by as much as 85 percent,” Lewis said. She added that the additional capabilities of the Opteron help save money, but dont add to the cost themselves. Opterons equipped with PowerNow cost the same as Opterons did without it, she said.