Putting GameGrid to the
Test"> Three college students from the University of Wisconsin worked on the GameGrid serviceJohn Bethencourt, Matthew Hammer, and Kevin Dammoverseen by an MBA student, Fred Chang. Although IBM encouraged researchers to download the GameGrid-enhanced Quake 2 application, only 870 did so. In a stress test performed Wednesday, only 80 players were on the map at any one time. IBM used its own IBM X-series servers running dual 1.26-GHz Pentium III processors purchased in 2001, Kaufman said.GameGrid dynamically partitions areas of the game map, including players and objects, onto different servers. If a player or object, such as a rocket, moves from one server to another, the first server sends the players statethe players name, vector, velocity, and statisticsfrom one server to the next. When doing so, IBMs GameGrid software typically operated with latencies of 50 microseconds or less, according to Hammer. IBM researchers performed the demonstration by color-coding objects to match the specific server. Even if a player isnt physically "on" a server, he must still be able to "see" objects stored on another. The Quake code determines the state of the world every tenth of a second, Bethencourt said. If a group of players collects in some corner of the map, the grid software balances the load, redividing the map between servers so that no one server becomes overloaded, Hammer said. "Its a good system to handle load balancing," Hammer said. Initially, IBM dedicated 30 servers to the project; not as many IBM researchers downloaded the client as expected, Kaufman said, so only eight were required to run the final stress test. IBMs college interns are now involved in writing bot software to push the GameGrid software to its limits.
"We were able to run this just fine on some white-box hardware we bought from Frys," Kaufman said. "The back-end hardwares not really all that important. Whats really important is the interconnectwhether its 10-Mbit Ethernet or something like Gigabit Ethernet."