The evolution of cloud-computing imposes many challenges on performance testing and requires not only a different approach and methodology of performance evaluation and analysis, but also specialized tools and frameworks to support such work. In traditional performance testing, typically a single workload was run against a static test configuration. The main metrics derived from such experiments included throughput, response times, and system utilization at steady-state. While this may have been sufficient in the past, where in many cases a single application was run on dedicated hardware, this approach is no longer suitable for cloud-based deployments. Whether private or public cloud, such environments typically host a variety of applications on distributed shared hardware resources, simultaneously accessed by a large number of tenants running heterogeneous workloads. The number of tenants as well as their activity and resource needs dynamically change over time, and the cloud infrastructure reacts to this by reallocating existing or provisioning new resources. Besides metrics such as the number of tenants and overall resource utilization, performance testing in the cloud must be able to answer many more questions: How is the quality of service of a tenant impacted by the constantly changing activity of other tenants? How long does it take the cloud infrastructure to react to changes in demand, and what is the effect on tenants while it does so? How well are service level agreements met? What is the resource consumption of individual tenants? How can global performance metrics on application- and system-level in a distributed system be correlated to an individual tenant's perceived performance?

Live migration of virtual machines (VMs) can consume excessive time and resources, and may affect application performance significantly if VM memory pages get dirtied faster than their content can be transferred to the destination. Existing approaches to this problem transfer memory content faster with high-speed networks, slow down the dirtying of memory pages by throttling the execution of applications, or reduce the amount of memory content to be transferred, for example, using compression. However, these approaches incur high resource costs or application performance penalties. In this paper, we propose to skip the transfer of VM memory pages that need not be migrated for the execution of running applications at the destination, by exploiting applications' assistance. We have designed a generic framework for application-assisted live migration and then used it to build and evaluate JAVMM, which migrates VMs running various types of Java applications skipping the transfer of garbage in Java memory. Our experimental results show that JAVMM can reduce the completion time, the network traffic of transferring memory pages, and the application downtime of Java VM migration, all by up to over 90%, compared to the vanilla Xen VM migration, without incurring noticeable performance penalty to applications.

High-level synthesis is becoming more important in practical design environments to meet new system requirements and, increasingly, fault tolerance is one especially because of high-speed and low power demands. This paper explores several basic aspects of low-cost fault tolerant synthesis for practical linear systems. It deals with practical design constraints that require basic operations to be only performed by a limited processing resources and do not normally assign each operation a separate processing resource. Two core issues, partitioning and allocation, for fault tolerant synthesis are examined. Results demonstrate a high-level abstraction and framework for fault tolerant synthesis which is almost totally independent of the physical hardware implementation. Issues in designing 1-fault detectable FFT system are considered in detail to illustrate the significance and effects of fault tolerant synthesis schemes. Our ultimate goal is to incorporate these techniques in future automated design tools so that fault tolerance features can be part of the design options.