System allocates data center bandwidth more fairly

A webpage today is often the sum of many different components. A user’s home page on a social-networking site, for instance, might display the latest posts from the users’ friends; the associated images, links, and comments; notifications of pending messages and comments on the user’s own posts; a list of events; a list of topics currently driving online discussions; a list of games, some of which are flagged to indicate that it’s the user’s turn; and of course the all-important ads, which the site depends on for revenues.

With increasing frequency, each of those components is handled by a different program running on a different server in the website’s data center. That reduces processing time, but it exacerbates another problem: the equitable allocation of network bandwidth among programs.

Many websites aggregate all of a page’s components before shipping them to the user. So if just one program has been allocated too little bandwidth on the data center network, the rest of the page — and the user — could be stuck waiting for its component.

At the Usenix Symposium on Networked Systems Design and Implementation this week, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) are presenting a new system for allocating bandwidth in data center networks. In tests, the system maintained the same overall data transmission rate — or network “throughput” — as those currently in use, but it allocated bandwidth much more fairly, completing the download of all of a page’s components up to four times as quickly.

“There are easy ways to maximize throughput in a way that divides up the resource very unevenly,” says Hari Balakrishnan, the Fujitsu Professor in Electrical Engineering and Computer Science and one of two senior authors on the paper describing the new system. “What we have shown is a way to very quickly converge to a good allocation.”

Joining Balakrishnan on the paper are first author Jonathan Perry, a graduate student in electrical engineering and computer science, and Devavrat Shah, a professor of electrical engineering and computer science.