Memory virtualization in virtualized systems: segmentation is better than paging

TL;DR

This paper proposes Compromis, a novel memory management approach that replaces paging with segmentation in virtualized systems, significantly reducing overhead and outperforming existing solutions.

Contribution

It introduces a new memory management unit using segmentation for VM memory, challenging the necessity of paging in hypervisors and demonstrating substantial performance improvements.

Findings

Compromis outperforms shadow paging by up to 30%.

Compromis outperforms Extended Page Table by up to 370%.

Memory fragmentation is not a significant issue in virtualized datacenters.

Abstract

The utilization of paging for virtual machine (VM) memory management is the root cause of memory virtualization overhead. This paper shows that paging is not necessary in the hypervisor. In fact, memory fragmentation, which explains paging utilization, is not an issue in virtualized datacenters thanks to VM memory demand patterns. Our solution Compromis, a novel Memory Management Unit, uses direct segment for VM memory management combined with paging for VM's processes. The paper presents a systematic methodology for implementing Compromis in the hardware, the hypervisor and the datacenter scheduler. Evaluation results show that Compromis outperforms the two popular memory virtualization solutions: shadow paging and Extended Page Table by up to 30% and 370% respectively.