Using shadow page cache to improve isolated drivers performance.

Hao Zheng,Endong Wang,Zhengdong Zhu,Xiaoshe Dong,Baoke Chen,Chengzhe Liu

doi:10.1155/2015/896519

Abstract

With the advantage of the reusability property of the virtualization technology, users can reuse various types and versions of existing operating systems and drivers in a virtual machine, so as to customize their application environment. In order to prevent users' virtualization environments being impacted by driver faults in virtual machine, Chariot examines the correctness of driver's write operations by the method of combining a driver's write operation capture and a driver's private access control table. However, this method needs to keep the write permission of shadow page table as read-only, so as to capture isolated driver's write operations through page faults, which adversely affect the performance of the driver. Based on delaying setting frequently used shadow pages' write permissions to read-only, this paper proposes an algorithm using shadow page cache to improve the performance of isolated drivers and carefully study the relationship between the performance of drivers and the size of shadow page cache. Experimental results show that, through the shadow page cache, the performance of isolated drivers can be greatly improved without impacting Chariot's reliability too much.

Highlights

By transparently integrating a variety of hardware resources, the virtualization technology can provide reliable and customizable operating environment for users
We study the single-level shadow page caching for a driver’s write operation capture (SCDWC) algorithm: according to the principle of locality, this algorithm caches the information of recently written shadow pages and delays setting the write protection of these shadow pages to avoid page faults caused by a lack of write permissions
This paper mainly studies how to improve the capture efficiency of drivers’ write operation on the basis of ensuring the isolation property of Chariot and proposes an improved algorithm, SCDWC

Summary

Introduction

By transparently integrating a variety of hardware resources, the virtualization technology can provide reliable and customizable operating environment for users. If there are frequent interactions between a driver and the kernel, setting the VM’s shadow pages to read-only may cause great performance loss To this end, this paper mainly studies how to effectively capture the driver’s write operations to avoid large performance loss under the condition of ensuring the driver fault isolation. According to the principle of locality, it caches the information of shadow pages that are recently written and delays setting write protections of these shadow pages to avoid their permissions being repeatedly opened and closed To this end, this paper mainly studies how to effectively capture driver’s write operations without impacting a driver’s performance too much, while ensuring a high reliability property of Chariot.

Chariot Architecture

The Approach of Write Operation Capture

Shadow Page Cache Algorithm

Evaluation

Related Work

Conclusion