QoS-aware mechanisms for improving cost-efficiency of datacenters

Warehouse Scale Computers (WSCs) promise high cost-efficiency by amortizing power, cooling, and management overheads. WSCs today host a large variety of jobs with two broad performance requirements categories: latency-critical (LC) and best-effort (BE). Ideally, to fully utilize all hardware resources, WSC operators can simply fill all the nodes with computing jobs. Unfortunately, because colocated jobs contend for shared resources, systems with high loads often experience performance degradation, which negatively impacts the Quality of Service (QoS) for LC jobs. In fact, service providers usually over-provision resources to avoid any interference with LC jobs, leading to significant resource inefficiencies. In this dissertation, I explore opportunities across different system-abstraction layers to improve the cost-efficiency of dataceters by increasing resource utilization of WSCs with little or no impact on the performance of LC jobs. The dissertation has three main components. First, I explore opportunities to improve the throughput of multicore systems by reducing the performance variation of LC jobs. The main insight is that by reshaping the latency distribution curve, performance headroom of LC jobs can be effectively converted to improved BE throughput. I develop, implement, and evaluate a runtime system that achieves this goal with existing hardware. I leverage the cache partitioning, per-core frequency scaling, and thread masking of server processors. Evaluation results show the proposed solution enables 30% higher system throughput compared to solutions proposed in prior works while maintaining at least as good QoS for LC jobs. Second, I study resource contention in near-future heterogeneous memory architectures (HMA). This study is motivated by recent developments in non-volatile memory (NVM) technologies, which enable higher storage density at the cost of same performance. To understand the performance and QoS impact of HMAs, I design and implement a performance emulator in the Linux kernel that runs unmodified workloads with high accuracy, low overhead, and complete transparency. I further propose and evaluate multiple data and resource management QoS mechanisms, such as locality-aware page admission, occupancy management, and write buffer jailing. Third, I focus on accelerated machine learning (ML) systems. By profiling the performance of production workloads and accelerators, I show that accelerated ML tasks are highly sensitive to main memory interference due to fine-grained interaction between CPU and accelerator tasks. As a result, memory resource contention can significantly decreases the performance and efficiency gains of accelerators. I propose a runtime system that leverages existing hardware capabilities and show 17% higher system efficiency compared to previous approaches. This study further exposes opportunities for future processor architecturesElectrical and Computer Engineerin

Regional features and seasonality of land – atmosphere coupling over Eastern China

Land–atmosphere coupling is a key process of the climate system, and various coupling mechanisms have been proposed before based on observational and numerical analyses. The impact of soil moisture (SM) on evapotranspiration (ET) and further surface temperature (ST) is an important aspect of such coupling. Using ERA-Interim data and CLM4.0 offline simulation results, this study further explores the relationships between SM/ST and ET to better understand the complex nature of the land–atmosphere coupling (i.e., spatial and seasonal variations) in eastern China, a typical monsoon area. It is found that two diagnostics of land–atmosphere coupling (i.e., SM–ET correlation and ST–ET correlation) are highly dependent on the climatology of SM and ST. By combining the SM–ET and ST–ET relationships, two “hot spots” of land–atmosphere coupling over eastern China are identified: Southwest China and North China. In Southwest China, ST is relatively high throughout the year, but SM is lowest in spring, resulting in a strong coupling in spring. However, in North China, SM is relatively low throughout the year, but ST is highest in summer, which leads to the strongest coupling in summer. Our results emphasize the dependence of land–atmosphere coupling on the seasonal evolution of climatic conditions and have implications for future studies related to land surface feedbacks

Mitochondrial Calcium Transporters Mediate Sensitivity to Noise-Induced Losses of Hair Cells and Cochlear Synapses

Mitochondria modulate cellular calcium homeostasis by the combined action of the mitochondrial calcium uniporter (MCU), a selective calcium entry channel, and the sodium calcium exchanger (NCLX), which extrudes calcium from mitochondria. In this study, we investigated MCU and NCLX in noise-induced hearing loss (NIHL) using adult CBA/J mice and noise-induced alterations of inner hair cell (IHC) synapses in MCU knockout mice. Following noise exposure, immunoreactivity of MCU increased in cochlear sensory hair cells of the basal turn, while immunoreactivity of NCLX decreased in a time- and exposure-dependent manner. Inhibition of MCU activity via MCU siRNA pretreatment or the specific pharmacological inhibitor Ru360 attenuated noise-induced loss of sensory hair cells and synaptic ribbons, wave I amplitudes, and NIHL in CBA/J mice. This protection was afforded, at least in part, through reduced cleavage of caspase 9 (CC9). Furthermore, MCU knockout mice on a hybrid genetic CD1 and C57/B6 background showed resistance to noise-induced seizures compared to wild-type littermates. Owing to the CD1 background, MCU knockouts and littermates suffer genetic high frequency hearing loss, but their IHCs remain intact. Noise-induced loss of IHC synaptic connections and reduction of auditory brainstem response (ABR) wave I amplitude were recovered in MCU knockout mice. These results suggest that cellular calcium influx during noise exposure leads to mitochondrial calcium overload via MCU and NCLX. Mitochondrial calcium overload, in turn, initiates cell death pathways and subsequent loss of hair cells and synaptic connections, resulting in NIHL

Possible connection between anomalous activity of Scandinavian Atmospheric Teleconnection Pattern and winter snowfall in the Yangtze-Huaihe River Basin of China

The temporal and spatial characteristics of winter snowfall in the Yangtze–Huaihe River Basin (YHRB) of China and its possible connection with Scandinavian Atmospheric Teleconnection Pattern (SCAND) anomalies are explored based on daily meteorological data contained in the Daily Surface Climate Dataset for China (V3.0) during the period 1960–2012. Results show that winter snowfall in the YHRB exhibits consistent anomalies over the whole region for the interannual variation during 1960–2012. Further analysis suggests that winter snowfall anomalies in the YHRB are closely linked to the anomalous wintertime SCAND activity. When there is more winter snowfall in the YHRB, SCAND is usually in a positive phase, accompanied by a strengthened Urals blocking high and East Asian trough, which is conducive to strengthened cold-air activity, intensified vertical motions, and more water vapor transport in the YHRB. In contrast, less winter snowfall in the YHRB usually happens in the negative phase of SCAND. Our results provide useful information to better understand the relevant mechanism responsible for anomalous winter snowfall in this area

Application of Multiple Evaluation in Art Classroom Teaching in Rural Primary Schools

With the reform and development of China’s primary school art education, the art teaching activities have obtained constant improvement, and the multiple evaluation of art teaching plays an important role in the process of art teaching. Based on the current situation of the evaluation of art classroom teaching in rural primary schools, this article uses diversified evaluation methods, multi-dimensional evaluation subjects and multiple evaluation contents to change the traditional and single primary art classroom evaluation method, to strive to improve the quality of art classroom teaching and stimulate students' learning interests and adapt to the development needs of students with different personalities

A Preliminary Study on the Teaching Evaluation Language of Art Teachers in Rural Middle Schools

Teachers' teaching evaluation language is an important part of art class teaching, which can directly affect students' interest in art class. Taking the teaching evaluation language of rural art teachers as the research object, this paper analyzes the main problems existing in teachers' teaching evaluation language through questionnaire survey, case analysis and interview. This paper puts forward some improvement strategies for teachers' teaching evaluation language from the aspects of management, concept and use, so as to provide some reference for junior middle school art teachers' teaching evaluation language

Construction and Research of Formative Evaluation System in Fine Art Classroom Teaching in Rural Primary Schools

With the popularization of quality education, the teaching evaluation of fine art class in rural primary schools has become an important part of the new curriculum reform, which tests whether the teaching goals are effectively achieved. This paper takes the formative evaluation system of fine art classroom teaching in rural primary schools as the research object, analyzes the research status of the formative evaluation system in rural primary schools, and expounds the theoretical basis and construction principles of the formative evaluation system. This paper constructs a formative evaluation system of fine art classroom teaching in rural primary schools from the aspects of teachers and students inside and outside the classroom, teaching process and teaching effect, in order to effectively stimulate students' interest in learning and improve their aesthetic literacy

Classroom Teaching Evaluation of Chinese Painting as a Form of Fine Arts in Rural Junior High Schools

Teaching evaluation is an indispensable part of the teaching system of junior high school. In order to inherit the excellent traditional Chinese culture and arts, traditional Chinese painting has been paid more and more attention to in the fine art curriculum of rural junior high school. This paper takes the classroom teaching evaluation of traditional Chinese painting as a form of fine arts in rural junior high school as the research object, and analyzes the problems existing in the classroom teaching evaluation of traditional Chinese painting in rural junior high school. This paper puts forward the corresponding improvement measures from the aspects of comprehensive evaluation object, concrete evaluation content, flexible evaluation language and diversified evaluation subjects, in order to improve the evaluation level of fine art teachers' classroom teaching, improve students' aesthetic cognition and learning interest in traditional Chinese painting, and cultivate students' innovative thinking and spirit