Virtualization

Intro

Virtualization is the art of subdividing resources provided by modern computers in order to achieve maximum performance, isolated execution, maximum utilization, resource managed hardware sharing and so on. Virtualization is not a novel concept. Mainframes designed in the late '70s incorporated the idea of isolating hardware design and hardware-agnostic software execution. Virtualization exists in all aspects of modern high performance computing. We try to experiment on Virtualized I/O, especially in Network Device Virtualization.

Storage and Network I/O

We believe that modern High Performance Interconnection Networks provide abstractions that can be exploited in Virtual Machine execution environments but lack support in sharing architectures. Previous work has shown that integrating the semantics of Virtualization in specialized software that runs on Network Processors can isolate and finally minimize the overhead on the VM Hypervisor concerning access to the device by Guest VMs. Direct I/O has been proposed as the solution to the CPU overhead imposed by guest VM transparent services that can lead to low throughput for high bandwidth links. However, minimizing CPU overhead comes at the cost of giving away the benefits of the device driver model. Integrating protocol offload support (present in most modern NICs) in virtual network device drivers can lead to performance improvement. Bypassing the Hypervisor in data movement can also minimize the overhead imposed by heavy I/O but at the cost of safety and memory protection.

We envision a Virtualization-enabled High performance Network Interface that can achieve line-rate throughput and optimized sharing of Network I/O in Virtual Machines by utilizing commodity hardware and innovative resource-sharing virtualization architectures.

MyriXen (ongoing)

Data access in HPC infrastructures is realized via user-level networking and OS-bypass techniques through which nodes can communicate with high bandwidth and low-latency. Virtualizing physical components requires hardware-aided software hypervisors to control I/O device access. As a result, line-rate bandwidth or lower latency message exchange over 10GbE interconnects hosted in Cloud Computing infrastructures can only be achieved by alleviating software overheads imposed by the Virtualization abstraction layers, namely the VMM and the driver domains which hold direct access to I/O devices. We have designed MyriXen, a framework in which Virtual Machines efficiently share network I/O devices bypassing overheads imposed by the VMM or the driver domains. MyriXen permits VMs to optimally exchange messages with the network via a high performance NIC, leaving security and isolation issues to the Virtualization layers. Smart Myri-10G NICs provide hardware abstractions that facilitate the integration of the MX semantics in the Xen split driver model. With MyriXen, multiple VMs exchange messages using the MX message passing protocol over Myri-10G interfaces as if the NIC was assigned solely to them. We believe that MyriXen can integrate message passing based application in clusters of VMs provided by Cloud Computing infrastructures with near-native performance.

See the Virtualization Section in our Bibliography Portal for selected publications concerning Virtualization techniques.