1,720,961 research outputs found
Efficient Workload Colocation in Modern Data Centers
No full textDespite the high costs of acquisition and maintenance of modern data centers, machine resource utilization is often low. Servers running online interactive services are over-provisioned to support peak load (which only occurs for a fraction of the time), due to business continuity and fault-tolerance plans that dictate these services tolerate major unforeseen events (e.g., the failure of another data center). Underutilized computing resources correlate with reduced data center efficiency and capital losses incurred by operators.
Colocating different types of workloads is a promising solution to increase resource utilization. The challenges are protecting interactive services from resource interference and handling limited resource availability: if a best-effort workload directly competes for resources with an interactive service, the latter can fail to meet its service-level objectives (SLOs), impacting user experience and resulting in lost revenue.
In this dissertation we focus on how to mitigate CPU interference and limited memory availability when colocating interactive services with batch workloads such as data-parallel applications. Existing work on mitigating CPU interference assumes that progress and performance metrics are available in real-time, and that hardware support for low-level isolation mechanisms is prevalent, neither of which are always true in commercial environments. Furthermore, previous work on improving resource allocation in clusters does not attempt to over-commit memory due to concerns of unpredictable performance degradation and sporadic failures. We first focus on the colocation of open-source in-memory interactive services, and conduct a thorough investigation on how they are impacted by batch jobs. We find that existing isolation techniques do not prevent performance degradation, and explain in detail why they are insufficient. Second, we study the behavior of a large commercial-scale service (i.e., a component of a web search platform), finding that it is highly bursty. We show that, by keeping a headroom of idle cores available at all times, the serviceâ s response tail-latency is maintained within its SLO even under heavy load. Third, we address the impact of limited memory availability on data-parallel applications by identifying an intrinsic property of their tasks: memory elasticity â the ability to handle memory pressure by writing intermediate data to external storage, incurring only moderate performance penalties when memory-constrained. We further show that memory elasticity is prevalent across various data-parallel application frameworks. We implement a scheduler that leverages memory elasticity and achieves reduced job completion times and increased memory utilization.
We conclude that these techniques make it possible to colocate even highly-bursty latency-sensitive services with batch jobs, significantly increasing resource utilization.LABO
PerfIso:Performance Isolation for Commercial Latency-Sensitive Services
No full textLarge commercial latency-sensitive services, such as web search, run on dedicated clusters provisioned for peak load to ensure responsiveness and tolerate data center outages. As a result, the average load is far lower than the peak load used for provisioning, leading to resource under-utilization. The idle resources can be used to run batch jobs, completing useful work and reducing overall data center provisioning costs. However, this is challenging in practice due to the complexity and stringent tail-latency requirements of latency-sensitive services. Left unmanaged, the competition for machine resources can lead to severe response-time degradation and unmet service-level objectives (SLOs).
This work describes PerfIso, a performance isolation framework which has been used for nearly three years in Microsoft Bing, a major search engine, to colocate batch jobs with production latency-sensitive services on over 90,000 servers. We discuss the design and implementation of PerfIso, and conduct an experimental evaluation in a production environment. We show that colocating CPU-intensive jobs with latency-sensitive services increases average CPU utilization from 21% to 66% for off-peak load without impacting tail latency
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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