Processor Folding for Linux on Power
Winner of the Chrysler Praxis Award
A high-end IBM server has enough power to download all of the music in the iTunes catalog in 60 seconds. Performance like this is only achieved with the careful tuning of both the hardware and software of the computer.
IBM’s Power Hypervisor software allows multiple operating systems to run simultaneously on a server. This is difficult because it requires sharing the system hardware among all of the installed operating systems.
To take advantage of the hypervisor, IBM has built many features into the operating systems that utilize it. If a system has multiple processors, the Power Hypervisor can assign one or more processors to an operating system. If an operating system is not using one of its processors, it can release the processor to the Power Hypervisor so it can be used by the other operating systems on the machine. This process currently only happens when the processor is not being used.
Consider for a moment what would happen if an operating system with three processors allocated to it uses only 20% of each processor. Much of the processing power would be wasted. A new feature called processor folding could help reduce this waste. This feature would move the processes running on the one of the processors onto the remaining two then give the empty processor back to the Power Hypervisor.
Processor folding is a feature that increases server value by simply making better use of the processors. It is this problem that was given to us to solve.
Josh Detwiler, Mark Bernum, Ian De Silva
