Breakthrough in electricity usage could lead to big savings for data centers

Serial links are responsible for transferring data between microprocessors and other electronic devices. Although serial links are indeed important, they are idle 50% to 70% of the time. However, idle does not mean powered off.

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Current technology requires that the serial link remain powered, consuming as much as 20 percent of the microprocessor's power, which, when all else is considered, amounts to 70 percent of the data center's power consumption.

Breakthrough by University of Illinois researchers

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Pavan Kumar Hanumolu

A team of researchers in the Department of Electrical and Computer Engineering at the University of Illinois, led by Associate Professor Pavan Kumar Hanumolu and PhD student Tejasvi Anand, lead author of the paper, has developed a transceiver that transforms an "always-on" serial link into a burst-mode communications link that powers down when the link is idle but powers up again when needed.

"Ideally, a burst-mode link must be powered on/off for zero time, consume zero power in the powered-off state, and incur zero energy overhead during the powered-on/off transitions," reads the abstract of the research paper written by the team. "However, these requirements are difficult to meet in practice; burst-mode communication suffers from reduced efficiency in achieving energy proportional operation."

It’s difficult, but it can be done

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Tejasvi Anand

The research, sponsored by Semiconductor Research Corp. of Research Triangle Park, North Carolina, aims to reduce the power consumption of serial links by eliminating power-hungry components of the link, Hanumolu explained.

"Zero power consumption" may or may not be possible, but the research team has improved on previous burst mode technology, which has a power-on/power-off time of hundreds of nanoseconds for memory interfaces and a few microseconds for Energy Efficient Ethernet. "Long power-on lock times limit the opportunity to save power in serial links," explains a press release introducing the breakthrough. "This research at the University of Illinois has reduced the power-on lock time to less than 20 nanoseconds, which has the effect of reducing power consumption by 44 times."

"The team estimates that North American data centers could save $870 million per year using this approach, and by 2020, data centers around the world could save an equivalent amount of serial link power to Japan in a single year," the release from the Department of Electrical and Computer Engineering at the University of Illinois states.

Transceiver Hardware Specifications

To get a rough idea of ​​what the researchers achieved, you need to unpack the title of the paper: 3.7A 7Gb/s Fast Power-On/Off Embedded Clock Serial Link Transceiver with 20ns Power-On Time and Power-Proportional Link Consumption of Only 740uW in the Power-Off State in 65nm CMOS.

The device includes a 7 Gbps transceiver that takes 20 nanoseconds to switch from a powered-off state to a fully powered-on state. When the link is powered off, the power consumption of the link in the powered-off state is 740 microwatts, which Hanumolu and Anand achieved almost zero power consumption. The 65-nanometer CMOS mentioned in the title of the paper refers to the complementary metal oxide semiconductor (CMOS) manufacturing process with a board line width of 65 nanometers.

“The reduction in serial link power consumption not only benefits processors and mobile platforms, but also continues to reap the benefits of Moore’s Law, as computing power and off-chip bandwidth can increase for several more years without adding pressure on processor power consumption,” Hanumolu said.

The transceiver technology developed by Hanumolu and Anand is suitable for applications in memory and network environments, and from a manufacturing perspective, it can be applied to any technology node. If I understand correctly, this research is also expected to improve the power consumption of mobile devices.

English: Save millions on data centers, thanks to a power usage breakthrough