Predictable Packet Latency in Xen-ARM

Seehwan YOO  Kuenhwan KWAK  Jaehyun JO  Chuck YOO  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E95-D   No.11   pp.2613-2623
Publication Date: 2012/11/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E95.D.2613
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Software System
Keyword: 
virtual machine,  I/O latency,  

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Summary: 
In this paper, we address latency issue in Xen-ARM virtual machines. Despite the advantages of virtualization in mobile systems, the current Xen-ARM is difficult to apply to mobile devices because it has unpredictable I/O latency. This paper analyzes the latency of incoming packet handling in Xen-ARM, and presents how virtualization affects the latency in detail. To make the latency predictable, firstly, we modify Xen-ARM scheduler so that the driver domain can be promptly scheduled by the hypervisor. Secondly, we introduce additional paravirtualization of guest OS that minimizes non-preemptible code path. With our enhancements, 99% of incoming packets are predictably handled within one millisecond at the destined guest OS, which is a feasible time bound for most soft real-time applications.