The ever-growing demand for more memory capacity from applications has always been a challenging factor in computer architecture. The advent of the Non Unified Memory Access (NUMA) architecture has achieved to work around the physical constraints of a single processor by providing more system memory using pools of processors, each with their own memory elements, but with variable access times. However, the efficient exploitation of such computing systems is a non-trivial task for software engineers. We have observed that the performance of more than half of the applications picked from two distinct benchmark suites is negatively affected when running on a NUMA machine, in the absence of manual tuning. This finding motivated us to develop a new profiling tool, so called PerfUtil, to study, characterize and better understand why those benchmarks have sub-optimal performance on NUMA machines. PerfUtil's effectiveness is based on its ability to track numerous events throughout the system at the managed runtime system level, that, ultimately, assists in demystifying NUMA peculiarities and accurately characterize managed applications profiles. CCS CONCEPTS • Software and its engineering → Software design engineering.

Data centers are currently constructed with fixed blocks (blades); the hard boundaries of this approach lead to suboptimal utilization of resources and increased energy requirements. The dReDBox (disaggregated Recursive Datacenter in a Box) project addresses the problem of fixed resource proportionality in next-generation, low-power data centers by proposing a paradigm shift toward finer resource allocation granularity, where the unit is the function block rather than the mainboard tray. This introduces various challenges at the system design level, requiring elastic hardware architectures, efficient software support and management, and programmable interconnect. Memory and hardware accelerators can be dynamically assigned to processing units to boost application performance, while high-speed, low-latency electrical and optical interconnect is a prerequisite for realizing the concept of data center disaggregation. This chapter presents the dReDBox hardware architecture and discusses design aspects of the software infrastructure for resource allocation and management. Furthermore, initial simulation and evaluation results for accessing remote, disaggregated memory are presented, employing benchmarks from the Splash-3 and the CloudSuite benchmark suites.

In the recent years, we have witnessed an explosion of the usages of Virtual Machines (VMs) which are currently found in desktops, smartphones, and cloud deployments. These recent developments create new research opportunities in the VM domain extending from performance to energy efficiency, and scalability studies. Research into these directions necessitates research frameworks for VMs that provide full coverage of the execution domains and hardware platforms. Unfortunately, the state of the art on Research VMs does not live up to such expectations and lacks behind industrialstrength software, making it hard for the research community to provide valuable insights.This paper presents our work in attempting to tackle those shortcomings by introducing Beehive, our vision towards a modular and seamlessly extensible ecosystem for research on virtual machines. Beehive unifies a number of existing state-of-the-art tools and components with novel ones providing a complete platform for hardware/software co-design of Virtual Machines.

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