Power efficiency is a key metric for Advanced Micro Devices engineers when they’re designing the company’s processors, and that is best illustrated by the vendor’s stated goal of improving the energy efficiency of its mobile platform by 25 times between 2014 and 2020.
AMD’s new “Carrizo” accelerated processing unit (APU) is a key step in that journey, according to company officials. Offering 23 percent greater density and lower power over the previous “Kaveri” chip, Carrizo is the first product introduced under the 25×20 initiative.
Carrizo—the 6th Generation A-Series APUs—and the need for greater energy efficiency in the industry and the world were the subject of an afternoon-long event last week at AMD’s Sunnyvale, Calif. offices, where company officials talked about how engineers were able to increase the density, power efficiency and performance of Carrizo while keeping it in the same 28-nanometer technology node.
They also talked about the need to drive down power consumption in technology products, particularly given the staggering growth in the expected numbers of electronic devices as the Internet of things (IoT) evolves, the push by companies to save money in the systems they run and the international efforts to battle the threat of climate change.
By 2020, ICT will represent more than 14 percent of electricity use in the world, according to Tim Mohin, director of corporate responsibility at AMD.
“Energy use is correlated to climate change,” Mohin said during a presentation. “This represents a threat but also an opportunity.”
For AMD, that is the opportunity to continue to make power efficiency a cornerstone of its products and to carve out more market share in a PC chip space dominated by larger rival Intel. It’s also an opportunity to help customers drive down the cost of their PC infrastructures and to reach the sustainability goals that many have set for themselves.
The challenge is doing all this at a time when the energy and compute demands are going up and climate change becomes an increasing concern, he said.
Both AMD and Intel have been driving power efficiency in their chips in recent years. Intel is making its next generation of processors—the 14nm “Skylake” chips—both more powerful and more efficient.
AMD on Sept. 17 released the results of a carbon footprint analysis of Carrizo and its new “Excavator” CPU core. It found that using the processor can lead to a 50 percent reduction in greenhouse gas emissions when compared with Kaveri and its “Steamroller” core. For enterprises, the savings can be significant, according to AMD officials.
A business refreshing 100,000 PCs that used the Kaveri processors for systems powered by Carrizo could save about 4.9 million kilowatt hours of electricity and 3,350 metric tons of carbon—enough to power 461 homes—over three years, Mohin said. The electricity savings translate to about $495,000.
That financial impact is important given corporate demand for a return on investments made in more energy-efficient technologies, according to Mohin and officials with AMD partners and customers. Adobe Systems buys thousands of PCs every year, according to Vince Digneo, sustainability strategist at the company. While the average energy savings of $5 per every PC with Carrizo doesn’t look impressive, if viewed through the purchase of thousands of PCs at a time, “it becomes a really significant story,” Digneo said during a panel discussion at the AMD event.
“It has a large bearing on our purchasing decisions,” Digneo said. “We can reduce our carbon footprint over time with an improvement to PCs.”
Ryan Kanzler, sustainability insights and engagement manager at Hewlett-Packard, said power efficiency can be a selling point for PC vendors if they’re talking to the right customers and at the right time in the purchasing process.
“It can move the needle,” Kanzler said.
Editor’s note: This story was changed to reflect that AMD’s goal is to improve the energy efficiency of its mobile processors by 25 times by 2020.
AMD Puts Focus on Power Efficiency of Carrizo
Power efficiency is a growing concern for many businesses, Mohin said, noting that 60 percent of Fortune 100 companies have established goals for reducing greenhouse gas emissions. Businesses “are starting to be forward-looking and starting to ask the right questions,” said Aditi Mohapatra, associate director of the ICT practice at Business for Social Responsibility.
For AMD, reaching the goals set forth in its 25×20 initiative is daunting, according to Sam Naffziger, AMD corporate fellow. Moore’s Law called for the doubling in the number of transistors on chips every 18 to 24 months, leading to improvements in both performance and power efficiency. However, gains in energy efficiency have slowed since about 2000 due to the challenges inherent in shrinking the components inside the chips. AMD’s goal is to exceed the historical efficiency trend predicted by Moore’s Law by at least 70 percent, Naffziger said during a presentation.
Carrizo gets AMD on its way. According to Naffziger, for the vendor to reach its goal by 2020, each chip generation will have to improve its power efficiency 1.7 times over the previous generation. AMD got a 2.4-times improvement with Carrizo.
For its engineers, the challenge was improving the performance and power efficiency while staying within the same 28nm node as Kaveri. Naffziger outlined some of the steps the engineers took when developing Carrizo. Among them were a high-density library design, better power management between the CPU and GPU on the die, and a reduction in the power needed for communications between the CPU and GPU. They increased the Level 1 cache while reducing the L2 cache, and reduced power consumption through better clock gating and other array changes.
The chip’s shared memory interface also saves power, he said.
However, the engineers also had to balance the drive for power reduction with the need for performance gains, Naffziger said.
“This isn’t just about low power and efficiency, because low power isn’t anything without performance,” he said.
The company was able to increase the frequency of the Excavator core—which is optimized for a 15-watt design point—by 39 percent. In addition, various enhancements—from the larger L1 cache and pre-fetch improvements to better branch prediction and new instruction support—translate to a 10 percent to 15 percent improvement in instructions per clock.
On the graphics side, AMD was able to increase the frequency up to 18 percent, and Carrizo is able to use all eight graphics cores, while Kaveri could use just six.