Virtualization in HPC Minesh Joshi CSC 469 Dr. Box Feb 1, 2012

Introduction HPC differ from type of server and the workloads at the workstation Hardware virtualization has been an important factor Virtualization helps in advancing the power or HPC HPC operating systems preserve the legacy compatibility Multiple operating systems can coexist on one physical machine Machine is multiplexed by a small privileged kernel, known as hypervisor or virtual machine monitor (VMM) VMM gives illusion of one or more machines

Coexistence of operating systems avoids incompatibilities, reduces testing and upgrade costs. Virtualization enables the specification of operating systems with full control over hardware resources. Hypervisor multiplexes the hardware resources HPC application can bypass legacy OS mechanisms and algorithms. Virtual machines communicate via low-overhead and low-latency communication mechanism

Productivity Hypervisor allows VM to monitor state, interrupts and communications of another VM Hypervisor can provide a virtual cluster of VMs Productivity can be enhanced by using virtual cluster Virtual reboot avoids the latencies of hardware re-initialization by the BIOS Decrease the start up time for the system by shipping VM image to all nodes in cluster

Performance Software pre-virtualization Specifying memory address translations Supports OSes Optimized for classes of HPC applications Hypervisor can guarantee resource allocations to a VM Allocation of fixed percentage of CPU cycles, or maximum latency Interrupts handling code for a real time VM Concurrent running of virtual cluster communicates nodes in real time

Focus on checkpoint/restart capability High priority work, inter-node migration of work in a cluster for load balancing Preemption allows real-time HPC These scenarios prosper the system availability Prevent long running HPC application loss

Security VM isolation provides a platform for building secure system Isolated VM have no unauthorized interaction Inrospection is used to monitor the communication and state of VM Only trusted program loaded into an isolated VM

Software complexity Hypervisor-based systems can reduce the complexity of software development Hypervisor should be sta ble than usual OS Hardware and software initialization done only once Maintenance of the system becomes more automated Gradually leads to improved software quality

Conclusion Virtualization helps HPC systems and applications Productivity, performance, reliability, availability, security, and simplicity