Utilizing Shared Memory for NFS Data Operations in Xen

Virtualization is becoming popular because it pro-vides server consolidation and ease of system admin-istration. Xen is an open source hypervisor based on paravirtualization which allows simultaneous execu-tion of multiple guest OSs. One interesting idea is that network communication between guest OSs can be replaced by the use of shared memory. This affects all applications that communicate amongst guest OSs and use network for the communication. A popular protocol to share data between multiple Linux ma-chines is NFS. We propose to modify NFS data op-erations to make use of shared memory when NFS client and server are running on two virtual machines running on Xen. We designed and implemented a new RPC read procedure. Normal NFS read opera-tion involves large data traffic on the network. The new procedure avoids overheads related with network communication by sending control messages over the network but passing data through shared memory. We implemented three variations of the new read pro-cedure and evaluated its performance using Iozone benchmarking tool and a custom tool.