Fog-supported delay-constrained energy-saving live migration of VMs over multiPath TCP/IP 5G connections

The incoming era of the fifth-generation fog computing-supported radio access networks (shortly, 5G FOGRANs) aims at exploiting computing/networking resource virtualization, in order to augment the limited resources of wireless devices through the seamless live migration of virtual machines (VMs) toward nearby fog data centers. For this purpose, the bandwidths of the multiple wireless network interface cards of the wireless devices may be aggregated under the control of the emerging MultiPathTCP (MPTCP) protocol. However, due to the fading and mobility-induced phenomena, the energy consumptions of the current state-of-the-art VM migration techniques may still offset their expected benefits. Motivated by these considerations, in this paper, we analytically characterize and implement in software and numerically test the optimal minimum-energy settable-complexity bandwidth manager (SCBM) for the live migration of VMs over 5G FOGRAN MPTCP connections. The key features of the proposed SCBM are that: 1) its implementation complexity is settable on-line on the basis of the target energy consumption versus implementation complexity tradeoff; 2) it minimizes the network energy consumed by the wireless device for sustaining the migration process under hard constraints on the tolerated migration times and downtimes; and 3) by leveraging a suitably designed adaptive mechanism, it is capable to quickly react to (possibly, unpredicted) fading and/or mobility-induced abrupt changes of the wireless environment without requiring forecasting. The actual effectiveness of the proposed SCBM is supported by extensive energy versus delay performance comparisons that cover: 1) a number of heterogeneous 3G/4G/WiFi FOGRAN scenarios; 2) synthetic and real-world workloads; and, 3) MPTCP and wireless connections

Dusty Caches to Save Memory Traffic

Reference counting is a garbage-collection technique that maintains a per-object count of the number of pointers to that object. When the count reaches zero, the object must be dead and can be collected. Although it is not an exact method, it is well suited for real-time systems and is widely implemented, sometimes in conjunction with other methods to increase the overall precision. A disadvantage of reference counting is the extra storage trac that is introduced. In this paper, we describe a new cache write-back policy that can substantially decrease the reference-counting traffic to RAM. We propose a new cache design that remembers the first-fetched value of a cache subblock, so that the subblock need not be written back to RAM unless a different value is present. We present results from experiments that show the effectiveness of this approach, particularly in mitigating the storage traffic due to reference counting

Profiling Essential Professional Skills of Chief Data Officers Through Topical Modeling Algorithms

Today enterprises are increasingly dependent on data to keep their business competitive and successful. To better harness values of data, more and more organizations are establishing Chief Data Officer (CDO) position. The professional skills of CDOs are rather diverse because CDOs are expected to undertake a variety of roles in their companies including enterprise data architect, data quality and governance manager, business strategy leader, business regulation compliance officer, etc. CDO is an emerging research field, few studies have been done on CDO. This paper tries to profile what are the key professional skills and education background that current CDOs have by studying their resumes on LinkedIn using topic modeling technique. This work is a step forward towards understanding the roles of CDOs in organizations and what are the professional skills and experience they may need have in order to undertake their responsibilities of managing data and realizing its true values for their organizations

A preliminary investigation of developer profiles based on their activities and code quality: who does what?

Developers work on different tasks in different conditions based on individual technical skills and personal habits. Identifying developer groups by mining their repositories is key for various tasks ranging from understanding developers types in open source projects, to help project managers concerned with the team allocation and coordination of human resources in companies. We aimed at identifying distinct groups of developer profiles based on well defined characteristics and at characterizing the most common quality issue types introduced by each profile in their code. We considered 77,932 commits of 33 open source Java projects, clustering their 2460 developers using dimensionality reduction techniques and applying the k-means algorithm. We identified five profiles among 2460 developers based on project experience, developer productivity and the common quality issues they introduce in the code. Results can be used by developer teams to detect and cope with harmful practices, in order to be more efficient by reducing the number of bugs they produce, looking for adequate training options, and balancing their teams.The research presented in this paper has been developed in the context of the TAED2 course at the GCED@FIB. This work has been partially funded by the “Beatriz Galindo” Spanish Program BEAGAL18/00064 and by the DOGO4ML Spanish research project (ref. PID2020-117191RB-I00)Peer ReviewedPostprint (author's final draft

“Is it a slow day or a go day?”: The perceptions and applications of velocity-based training within elite strength and conditioning

Velocity-based training (VBT) is a contemporary prescriptive, programming, and testing tool commonly utilised in strength and conditioning (S&C). Over recent years, there has been an influx of peer-reviewed literature investigating several different applications (e.g. load-velocity profiling, velocity loss, load manipulation, and reliability of technology) of VBT. The procedures implemented in research, however, do not always reflect the practices within applied environments. The aim of this study, therefore, was to investigate the perceptions and applications of VBT within elite S&C to enhance contextual understanding and develop appropriate avenues of practitioner-focused research. Fourteen high-performance S&C coaches participated in semi-structured interviews to discuss their experiences of implementing VBT into their practices. Reflexive thematic analysis was adopted, following an inductive and realist approach. Three central organising themes emerged: Technology, applications, and reflections. Within these central themes, higher order themes consisting of drivers for buying technology; programming, testing, monitoring, and feedback; and benefits, drawbacks, and future uses also emerged. Practitioners reported varied drivers and applications of VBT, often being dictated by simplicity, environmental context, and personal preferences. Coaches perceived VBT to be a beneficial tool yet were cognizant of the drawbacks and challenges in certain settings. VBT is a flexible tool that can support and aid several aspects of S&C planning and delivery, with coaches valuing the impact it can have on training environments, objective prescriptions, tracking player readiness, and programme success.publishedVersio