Satori: Enlightened Page Sharing

We introduce Satori, an efficient and effective system for sharing memory in virtualised systems. Satori uses enlightenments in guest operating systems to detect sharing opportunities and manage the surplus memory that results from sharing. Our approach has three key benefits over existing systems: it is more able to detect short-lived sharing opportunities, it is efficient and incurs negligible overhead, and it maintains better performance isolation between virtual machines. We have implemented and evaluated a prototype of Satori for the Xen virtual machine monitor. In our evaluation, we show that Satori quickly exploits up to 94% of the maximum possible sharing with insignificant performance overhead. Furthermore, we demonstrate workloads where the additional memory improves macrobenchmark performance by a factor of two.