Characterizing the Performance of Parallel Applications on Multi-socket Virtual Machines

Abstract

Abstract-In this paper we characterize the behavior with respect to memory locality management of scientific computing applications running in virtualized environments. NUMA locality on current solutions (KVM and Xen) is enforced by pinning virtual machines to CPUs and providing NUMA aware allocation in hypervisors. Our analysis shows that due to two-level memory management and lack of integration with page reclamation mechanisms, applications running on warm VMs suffer from a "leakage" of page locality. Our results using MPI, UPC and OpenMP implementations of the NAS Parallel Benchmarks, running on Intel and AMD NUMA systems, indicate that applications observe an overall average performance degradation of 55% when compared to native. Runs on "cold" VMs suffer an average performance degradation of 27%, while subsequent runs are roughly 30% slower than the cold runs. We quantify the impact of locality improvement techniques designed for full virtualization environments: hypervisor level page remapping and partitioning the NUMA domains between multiple virtual machines. Our analysis shows that hypervisor only schemes have little or no potential for performance improvement. When the programming model allows it, system partitioning with proper VM and runtime support is able to re-produce native performance: in a partitioned system with one virtual machine per socket the average workload performance is 5% better than native.

The Magellan Final Report on Cloud Computing

“…Further investigation of the impact of the memory cache was out of the scope of this project. Other studies have shown the effects of memory performance in VMs [43] …”

Security Vulnerability Analysis in Virtualized Computing Environments

“…The listing is intended to identify vulnerabilities to indicate that although the technology may be relatively new to an enterprise environment, the amount of implications evident in the products is growing as use increases. To mitigate the risk associated with rogue or phantom virtualization architectures, as well as unpatched or improperly patched VMs, the following are several security recommendations aimed at securing these types of environments: [20]. Deny all write, copy, and execute access to this directory, except for an administrative role associated with virtualization management.…”

“…The key element becomes this decoupling of the logical resource from the physical resource where the current programs and data in use are held, which can affect performance. Virtualization technologies attempt to provide high virtualized system performance through open source solutions such as kernel-based VMs [20], Xen [2] and proprietary solutions such as Intel's VT-x and VT-I [54] and HyperDealer [19].…”

Risk assessment in service provider communities

“…By deploying a secure multi-tenant virtual service provision mechanism, each business unit benefits from the transparency of the virtual environment [15]. Hence, a multi-tenancy architecture enables the provision of new services quickly and cost effectively by using Service Level Agreements (SLAs) [17], [14].…”