Abstract
In virtualized environments, memory overcommitment can enhance the machine utilization, because the number of virtual machines (VMs) that can be launched on a single physical machine simultaneously is primarily determined by the size of physical memory. One technique to achieve memory overcommitment is memory de-duplication, which detects and merges the identical memory pages across different virtual machines. The state of art implementation of memory de-duplication is vanilla KSM (Kernel Same-paging Merging), which however is slow in the start-up time, the time from activating to converging. In this thesis, we present the HZ (Hot-Zone) KSM to accelerate the start-up time of KSM. A memory page is called hot if it is likely to be merged. We have observed that different virtual machines that run the same operating systems and applications could have similar hot pages. Therefore, the memory hot zones can be learned from historical statistics. HZ KSM searches the merge-able pages in the hot-zones more frequently to shorten the start-up time. Since the number of hot pages is relatively small, HZ KSM does not increase the CPU time significantly. Experimental results show that HZ KSM can reduce the 30% of start-up time comparing to vanilla KSM.