If the battery on your next MP3 player lasts significantly longer than the one on your last player, it may be thanks to Partha Ranganathan. The principal research scientist at Hewlett-Packard Labs (Palo Alto, Calif.) is on a quest to find ways to use power and multicore processors more effectively across a broad range of devices.
Ranganathan has spent the past seven years at HP Labs after getting his doctorate in electrical and computer engineering at Rice University. In recognition of his accomplishments, MIT Technology Review named him to its list of the top technology innovators under age 35 for 2007.
Ranganathan helped define a way to light only the pixels a user needs to see on a handheld device using an organic LED or other emissive display. The technique could extend battery life on the system tenfold. But most of his efforts have been in the area of data center computing, closer to HP's mainstream businesses in servers and storage arrays. Among other projects, he has helped define two benchmarks that could be useful in measuring a system's energy efficiency.
"Everyone knows we all want to go green, but no one knows when we can declare victory," Ranganathan said.
The Joulesort benchmark provides a guideline for optimizing the energy efficiency of a system in development. It is now going through academic review to determine its usefulness beyond HP's walls.
Another metric, the Energy Scale-Down Efficiency measurement, checks the power used by systems operating at the low utilization levels typical of many servers in the field. "This will be adopted faster because it is a big problem in our industry," he said.
An ambitious project called Power Struggle aims to define an overarching scheme for coordinating power management across systems and components. "Today we have power management technologies at the chip, operating system, blade, system and data center levels," he said. "One of the big challenges of the next three to five years is, how do we put these all together? Will they all work together and be globally optimal?"
Ranganathan and colleagues have defined a specification for a high-level framework that could manage interfaces between power management tech- nologies to coordinate their efforts. A prototype of the framework showed the potential to save 60 to 70 percent of typical power and 25 to 30 percent of capital expenses for a data center.
He is also researching the best uses of multicore processors. A recent paper showed the benefits of dedicating some cores to accelerating key operating system calls that do not require much context switching. "We saw tremendous benefits in power efficiency, performance and security," he said.
Another paper explored how to manipulate large unstructured data sets in storage for jobs such as search, finding malware or superimposing images.
Computer science research was a natural path for Ranganathan, whose mother is a teacher and father is a math professor. He takes a practical approach to his work in areas such as power conservation. "I am not necessarily a tree hugger. These techniques impact the bottom line, saving people money and extending the life of batteries in their systems," he said.
"One of the fun things about working at HP is it has a product portfolio that really touches people's lives. The breadth across which I can operate is exciting."