AMD Talks Energy Efficiency, Performance With Carrizo Chip

At the ISSCC, the chip maker said its latest APU offers significant gains in performance-per-watt, energy efficiency and battery life.

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Advanced Micro Devices officials several months ago announced the company's forthcoming "Carrizo" processors for notebooks and low-power desktops in an effort to regain momentum in a PC chip market dominated by larger rival Intel.

The officials have since boasted about the significant power savings of the processors, along with longer battery life and improvements in performance due to new compute cores and graphics technologies.

On Feb. 23, during a presentation at the International Solid-State Circuits Conference (ISSCC) in San Francisco, AMD engineers offered up more details about the chips, saying Carrizo offers the greatest performance-per-watt gains in the company's mainstream accelerated processing units (APUs).

"We've come up with a very competitive product from a performance and battery life perspective … with a very efficient design," AMD Corporate Fellow Sam Naffziger told eWEEK.

The chips will be fully compliant with the Heterogeneous System Architecture (HSA) 1.0—which makes it easier to move workloads between the CPU and GPU. Enhanced energy management technologies are helping to drive down power consumption, said Naffziger, who gave the presentation on Carrizo.

Carrizo is the last of the chips based on the Bulldozer architecture and introduces the "Excavator" x86 CPU cores and the latest generation of AMD's Radeon Graphics Cores Next (GCN) architecture. Using a system-on-a-chip (SoC) design, Naffziger said he expects Carrizo's x86 cores—through a 5 percent increase in instructions-per-clock on a size 23 percent smaller than on the current Kaveri APUs—to drive down power consumption by 40 percent over Kaveri. In addition, the eight Radeon cores consume 20 percent less power than those on Kaveri.

At the conference, the AMD engineer disclosed that the 28-nanometer Carrizo will offer 29 percent more transistors—3.1 billion—on a die size almost the same as Kaveri's. The new Radeon GPU cores come with dedicated power supplies and will offer double- digit percentage increases in both performance and battery life, he said. The new chip, which will begin appearing in systems later this year, also supports H.265 video decoding.

Carrizo will be an important chip for AMD, according to Patrick Moorhead, principal analyst with Moor Insights and Strategy. "Carrizo is the chance to win back 3, 4, 5 percent of market share not only with an improved core, but also with significant improvements in graphics and significant improvements in performance-per-watt," Moorhead told eWEEK. "It's huge for AMD, which has been in a little bit of a market-share free fall."

He noted the full HSA capabilities hold the potential to enable AMD to differentiate itself in the market by enabling systems powered by Carrizo to run difficult workloads well. Software will be able to do a lot with the GPU that it couldn't do before, Moorhead said. The challenge for AMD will be whether operating systems will be able to take advantage of a fully-compliance HSA processor.

"There's a lot of potential, but there's also a lot of unknowns," he said.

On the architectural side, the greater transistor density on a die almost the equal of Kaveri means greater real estate for graphics and multimedia on a single chip. It also allows for the integration of the Southbridge on the chip as well.

The power efficiency gains come from several new technologies, including some to optimize voltage. One brings what AMD calls voltage adaptive operation functions to both the CPU and GPU. The technology makes frequency adjustments a the nanosecond level, which preserves the compute performance but cuts power consumption by up to 10 percent in the GPU and 19 percent in the CPU.

AMD also is leveraging adaptive voltage and frequency scaling (AVFS), which enables APUs to adapt in real time to their own silicon characteristics, platform behavior and operating environment, which can result in power savings of up to 30 percent. In addition, the tuning of the GPU for optimal power efficiency leads to the 20 percent power reduction over the Kaveri GPUs.

Carrizo and the new technologies in the chips also represent another step forward in AMD's ambitious effort to improve the energy efficiency of its APUs 25-fold by 2020. The company announced the initiative last year.

"We don't know how we're going to get there for sure," AMD's Naffziger said. "With Carrizo, we pulled a lot of knobs, so we're getting there."