Microsoft's Lite Green: Saving Energy

The word Microsoft Research Labs sketches a, seemingly, impossible dream of prototypes of coffee-serving robots. There are prototypes but not as glamorous as bionic coffee-serving pastry chefs. The most exciting one of those is called Lite Green.

In this cumbersome economic atmosphere CIOs fear budget cuts, come the new-year allocations, and now with enterprises thrusting majority of the power bill on the IT department, the CIOs need a plan. Most CIOs have done what they could to turn greener, but the bills seem never to come down.

The Microsoft Research Labs in India have been working on a project-Lite Green-to reduce the bills, be energy efficient and increase efficiency.

The Problem

Desktops, when running at full capacity consume close to 100-200 watts and 60 to 80 Watts when running at close to zero percent CPU usage.

“If you put your machine to sleep, it will only consume 2 watts,” says Ramachandran Ramjee, Microsoft Research. But standby isn't preferred by many users; once the PC is put to sleep the machine would not be able to engage in network activity, it could potentially block-off system administrators who use inactive times to update software and general internal upkeep.

A white paper published by one of the researchers describes the challenges of putting the machine to sleep as: in some cases, sleep causes a hard failure, e.g., a broken connection; in other cases, it causes a soft failure. For example, if a user steps out for a meeting and their (idle) machine goes to sleep, IM might show them, somewhat misleadingly, as being “offline” when “away” would be more appropriate. Users care about preserving long-running network connections (e.g., login sessions, IM presence, file sharing), background computation (e.g., syncing and automatic filing of new emails), and keeping their machine reachable even while it is idle.

A solution was required to continue the undisrupted user experience and save energy. Lite Green fits both into one by using the concept of virtualization.

The Solution

Using virtualization or “live migration”, the working environment is carted off to a server. The memory pages are copied on the server, over a high-speed LAN, while the virtual machine continues execution, pauses briefly-60 ms-and then resumes execution on the server. The solution here is to automate the process of migrating the desktop to a central machine. “The idle time, according to default policy, is ten minutes but can be reduced to one,” says Ramjee.

The usual problem with recovering a sleeping machine is reduced. It takes five seconds to “wake up” and a minute to get the virtual machine back to the host. This project is most effective during weekends and overnight-16 and 63 hours respectively-where there is an amount of activity required to be done away from the desktop is high and the access through remote desktop is imperative. “The energy savings is close to 80 per cent,” said Ramjee.

Lite Green, unfortunately, is still a prototype and is not on the shelves yet and MSR remains tight lipped on when the product could start being picked up by the market.