Managing contamination delay to improve Timing Speculation architectures

Timing Speculation (TS) is a widely known method for realizing better-than-worst-case systems. Aggressive clocking, realizable by TS, enable systems to operate beyond specified safe frequency limits to effectively exploit the data dependent circuit delay. However, the range of aggressive clocking for performance enhancement under TS is restricted by short paths. In this paper, we show that increasing the lengths of short paths of the circuit increases the effectiveness of TS, leading to performance improvement. Also, we propose an algorithm to efficiently add delay buffers to selected short paths while keeping down the area penalty. We present our algorithm results for ISCAS-85 suite and show that it is possible to increase the circuit contamination delay by up to 30% without affecting the propagation delay. We also explore the possibility of increasing short path delays further by relaxing the constraint on propagation delay and analyze the performance impact

ON REDUCING THE DECODING COMPLEXITY OF SHINGLED MAGNETIC RECORDING SYSTEM

Shingled Magnetic Recording (SMR) has been recognised as one of the alternative technologies to achieve an areal density beyond the limit of the perpendicular recording technique, 1 Tb/in2, which has an advantage of extending the use of the conventional method media and read/write head. This work presents SMR system subject to both Inter Symbol Interference (ISI) and Inter Track Interference (ITI) and investigates different equalisation/detection techniques in order to reduce the complexity of this system. To investigate the ITI in shingled systems, one-track one-head system model has been extended into two-track one-head system model to have two interfering tracks. Consequently, six novel decoding techniques have been applied to the new system in order to find the Maximum Likelihood (ML) sequence. The decoding complexity of the six techniques has been investigated and then measured. The results show that the complexity is reduced by more than three times with 0.5 dB loss in performance. To measure this complexity practically, perpendicular recording system has been implemented in hardware. Hardware architectures are designed for that system with successful Quartus II fitter which are: Perpendicular Magnetic Recording (PMR) channel, digital filter equaliser with and without Additive White Gaussian Noise (AWGN) and ideal channel architectures. Two different hardware designs are implemented for Viterbi Algorithm (VA), however, Quartus II fitter for both of them was unsuccessful. It is found that, Simulink/Digital Signal Processing (DSP) Builder based designs are not efficient for complex algorithms and the eligible solution for such designs is writing Hardware Description Language (HDL) codes for those algorithms.The Iraqi Governmen

The New Hampshire, Vol. 45, No. 14 (May 12, 1955)

An independent student produced newspaper from the University of New Hampshire

Caches collaboratifs noyau adaptés aux environnements virtualisés

With the advent of cloud architectures, virtualization has become a key mechanism for ensuring isolation and flexibility. However, a drawback of using virtual machines (VMs) is the fragmentation of physical resources. As operating systems leverage free memory for I/O caching, memory fragmentation is particularly problematic for I/O-intensive applications, which suffer a significant performance drop. In this context, providing the ability to dynamically adjust the resources allocated among the VMs is a primary concern.To address this issue, this thesis proposes a distributed cache mechanism called Puma. Puma pools together the free memory left unused by VMs: it enables a VM to entrust clean page-cache pages to other VMs. Puma extends the Linux kernel page cache, and thus remains transparent, to both applications and the rest of the operating system. Puma adjusts itself dynamically to the caching activity of a VM, which Puma evaluates by means of metrics derived from existing Linux kernel memory management mechanisms. Our experiments show that Puma significantly improves the performance of I/O-intensive applications and that it adapts well to dynamically changing conditions.Avec l'avènement du cloud computing, la virtualisation est devenue aujourd'hui incontournable. Elle offre isolation et flexibilité, en revanche elle implique une fragmentation des ressources, et notamment de la mémoire. Les performances des applications qui effectuent beaucoup d'entrées/sorties (E/S) en sont particulièrement impactées. En effet, celles-ci reposent en grande partie sur la présence de mémoire libre, utilisée par le système pour faire du cache et ainsi accélérer les E/S. Ajuster dynamiquement les ressources d'une machine virtuelle devient donc un enjeu majeur. Dans cette thèse nous nous intéressons à ce problème, et nous proposons Puma, un cache réparti permettant de mutualiser la mémoire inutilisée des machines virtuelles pour améliorer les performances des applications qui effectuent beaucoup d'E/S. Contrairement aux solutions existantes, notre approche noyau permet à Puma de fonctionner avec les applications sans adaptation ni système de fichiers spécifique. Nous proposons plusieurs métriques, reposant sur des mécanismes existants du noyau Linux, qui permettent de définir le niveau d'activité « cache » du système. Ces métriques sont utilisées par Puma pour automatiser le niveau de contribution d'un noeud au cache réparti. Nos évaluations de Puma montrent qu'il est capable d'améliorer significativement les performances d'applications qui effectuent beaucoup d'E/S et de s'adapter dynamiquement afin de ne pas dégrader leurs performances

Toward timely, predictable and cost-effective data analytics

Modern industrial, government, and academic organizations are collecting massive amounts of data at an unprecedented scale and pace. The ability to perform timely, predictable and cost-effective analytical processing of such large data sets in order to extract deep insights is now a key ingredient for success. Traditional database systems (DBMS) are, however, not the first choice for servicing these modern applications, despite 40 years of database research. This is due to the fact that modern applications exhibit different behavior from the one assumed by DBMS: a) timely data exploration as a new trend is characterized by ad-hoc queries and a short user interaction period, leaving little time for DBMS to do good performance tuning, b) accurate statistics representing relevant summary information about distributions of ever increasing data are frequently missing, resulting in suboptimal plan decisions and consequently poor and unpredictable query execution performance, and c) cloud service providers - a major winner in the data analytics game due to the low cost of (shared) storage - have shifted the control over data storage from DBMS to the cloud providers, making it harder for DBMS to optimize data access. This thesis demonstrates that database systems can still provide timely, predictable and cost-effective analytical processing, if they use an agile and adaptive approach. In particular, DBMS need to adapt at three levels (to workload, data and hardware characteristics) in order to stabilize and optimize performance and cost when faced with requirements posed by modern data analytics applications. Workload-driven data ingestion is introduced with NoDB as a means to enable efficient data exploration and reduce the data-to-insight time (i.e., the time to load the data and tune the system) by doing these steps lazily and incrementally as a side-effect of posed queries as opposed to mandatory first steps. Data-driven runtime access path decision making introduced with Smooth Scan alleviates suboptimal query execution, postponing the decision on access paths from query optimization, where statistics are heavily exploited, to query execution, where the system can obtain more details about data distributions. Smooth Scan uses access path morphing from one physical alternative to another to fit the observed data distributions, which removes the need for a priori access path decisions and substantially improves the predictability of DBMS. Hardware-driven query execution introduced with Skipper enables the usage of cold storage devices (CSD) as a cost-effective solution for storing the ever increasing customer data. Skipper uses an out-of-order CSD-driven query execution model based on multi-way joins coupled with efficient cache and I/O scheduling policies to hide the non-uniform access latencies of CSD. This thesis advocates runtime adaptivity as a key to dealing with raising uncertainty about workload characteristics that modern data analytics applications exhibit. Overall, the techniques introduced in this thesis through the three levels of adaptivity (workload, data and hardware-driven adaptivity) increase the usability of database systems and the user satisfaction in the case of big data exploration, making low-cost data analytics reality

Removal Period Cherokee Households in Southwestern North Carolina: Material Perspectives on Ethnicity and Cultural Differentiation

Nineteenth century accounts of Cherokee Indian society consistently refer to the existence of two classes among the Cherokees: the acculturated mixed blood[s], who speak English and are considered the intelligent and wealthy class and the culturally conservative fullbloods, whom white observers denigrated as backward, indolent, and ignorant pagans. This perceived dichotomy reflected the poles of a socioeconomic and cultural continuum that developed as a result of the differential Westernization of Cherokee individuals and households during the post-Revolutionary War era. As these socioeconomic classes diverged, they developed as the primary axis of competition and conflict within Cherokee society. Because these groups were progressively distinguished by ancestry, language use, lifestyle, and ideology, they may be characterized as emergent ethnic groups subsumed within the Cherokee national polity. As identity-conscious groups in competition for economic resources and political power, the Cherokee-speaking fullblood majority and the English-speaking metis minority used various media, including material goods and property, to construct and maintain ethnic boundaries. This study examines documentary and archaeological evidence for the use of such material media by Cherokee families in southwestern North Carolina during the Removal period. (1835-1838) and seeks to define material patterning that distinguished the English-speaking metis minority from the Cherokee-speaking fullblood majority. Four independent primary datasets are successively analyzed and discussed to accomplish a synthetic overview of Cherokee wealthholding and material culture. Bioracial, linguistic, and certain aspects of economic variation within the study population are defined through examination of the 1835 War Department census of the Cherokee Nation east of the Mississippi. General trends of bioracial endogamy, community composition, and wealth distribution evident in the 1835 census indicate active ethnic differentiation within the Cherokee population of southwestern North Carolina. The population of the study area was ethnically and socioeconomically homogeneous, with a dominant component of monolingual Cherokee fullblood subsistence farmers who formed a distinctly conservative and materially impoverished aboriginal stratum of Cherokee society. Contrasted with this majority was a small group of Anglo-Cherokee households who exhibited high rates of English literacy and slaveholding, and who managed extensive market farms in the larger river and creek valleys in the southern portion of the study area A relatively small number of fullblood and AngloCherokee families were arrayed between these extremes, forming a heavily skewed socioeconomic continuum largely reflective of household ethnicity. The improved real properties of Cherokee households in southwestern North Carolina are documented by U.S. government property appraisals conducted in the winter of 1836-1837. These appraisals include narrative descriptions and dimensions of dwellings and other buildings, cultivated fields and other cleared or fenced land, fruit trees, ditches, wells, mills, and other facilities present on 684 properties. Hierarchical agglomerative (Ward\u27s method) cluster analysis is used to define types of properties based upon similarities in the values assigned to dwellings, nonresidential structures, and agricultural improvements by the federal appraisers. The resultant cluster solution is interpreted as a series of farmstead models that can be ranked from those more traditional in composition to those more closely resembling Western agrarian modes. These analyses indicate that Cherokee properties in the study area were remarkably homogeneous in composition; more than 85% of the Cherokee farmsteads in southwestern North Carolina consisted of twelve or fewer acres of cropland, small, cribbed log dwellings valued less than $32.00, and few outbuildings other than corn cribs and an occasional asi. Properties owned by a small number of Anglo-Cherokees families contrast sharply with this traditional farmstead mode, and reflect thorough incorporation and integration of Western agrarian material modes of life. The largest and most highly valued Cherokee properties included substantial, hewn log dwellings valued in excess of$70.00, 35 or more acres of cropland, and a wide array of ancillary domestic structures (e.g. kitchens, springhouses, smokehouses), farm buildings (e.g. stables, cribs, barns), and specialized facilities (e.g. stores, mills, blacksmith shops). These farms substantially resembled the typical holdings of Anglo-American middling farmers and small planters in the southern highlands, and the Cherokee owners of such properties occupied a socioeconomic status parallel to the upper middle class of the Anglo-American rural South. A relatively small sector of Anglo-Cherokee and fullblood Cherokee families maintained homes and farms that formed a continuum between these extremes. Contrastive modes of farmstead composition are interpreted as evidence for the operation of distinct Western and traditional systems of household economy and material lifeways. These distinct systems are largely, but not exclusively, correlated with the bioracial and linguistic affinities of Cherokee households, and contrastive farmstead composition is interpreted as evidence for ethnic differentiation among Cherokee households in southwestern North Carolina. Spoliation claims which Cherokees from the study area filed against the United States government following forced removal of 1838 document losses of clothing, furniture, household goods, cookware and tableware, agricultural equipment and other tools, livestock, and other material possessions by more than 400 Cherokee households from the study area. These data are initially explored through univariate comparisons of the distributions of major functional groups of chattel property among bioracial/linguistic subsets of the study population to determine differential patterns of ownership. Hierarchical agglomerative cluster analysis is applied to classify individual household cases by inventory composition. The membership of these groups of households is then evaluated with respect to racial/ethnic affinity to determine whether ethnicity played a significant role in the formation of household assemblages. Analyses of the chattel properties data. reveal patterning similar to that of the real properties data, with a large, homogeneous group of relatively poor, predominantly fullblood families forming the basal economic stratum of Cherokee society contrasted with a small, predominantly English-speaking, group of wealthy Cherokees. A relatively small group of both fullblood and Anglo-Cherokee households span these extremes. These patterns are interpreted as evidence for a traditional-Western continuum in material lifestyles and economic modes; the poles of this continuum appear to represent the contrastive content of an ethnic dichotomy. Archaeological data present a collateral, yet independent gauge of variation in the material lifeways of Removal Period Cherokee households in the study area. To illustrate the differences in material culture that distinguish more Westernized from more traditionally oriented Cherokee households, artifact assemblages representing one Anglo-Cherokee metis occupation, and six fullblood Cherokee household occupations are compared and contrasted in terms of diversity, content, and relative composition. Archaeological assemblages recovered from surface and excavated contexts at these farmstead sites evince a high degree of interhousehold variation in scale and content; this variability is interpreted as evidence of differential acculturation and contrastive cultural orientations. Most of these assemblages are dominated by Qualla series ceramics and other goods reflective of indigenous traditions; these configurations suggest that many of the Cherokee inhabitants of southwestern North Carolina retained strong native identities expressed through continuity of traditional technologies. However, high frequencies of commercially manufactured goods associated with the metis household (the Christies) occupation also indicate substantially higher levels of material wealth and construction of a Westernized material lifestyle informed by AngloAmerican models. which commercial consumption was particularly prominent. These analyses illustrate the broad themes of variation in Cherokee material culture on the eve of the removal of 1838. The extremes of variation evident in these datasets are interpreted as evidence for differential Westernization of Cherokee households, and illustrate the material modes that conservative Cherokees and Westernized Anglo-Cherokees used to define and distinguish their communities of association as nascent ethnic groups struggling over the cultural identity and political fate of the Cherokee Nation

Obiter Dicta

"Stitched together over five years of journaling, Obiter Dicta is a commonplace book of freewheeling explorations representing the transcription of a dozen notebooks, since painstakingly reimagined for publication. Organized after Theodor Adorno’s Minima Moralia, this unschooled exercise in aesthetic thought—gleefully dilettantish, oftentimes dangerously close to the epigrammatic—interrogates an array of subject matter (although inescapably circling back to the curiously resemblant histories of Western visual art and instrumental music) through the lens of drive-by speculation. Erick Verran’s approach to philosophical inquiry follows the brute-force literary technique of Jacques Derrida to exhaustively favor the material grammar of a signifier over hand-me-down meaning, juxtaposing outer semblances with their buried systems and our etched-in-stone intuitions about color and illusion, shape and value, with lessons stolen from seemingly unrelatable disciplines. Interlarded with extracts of Ludwig Wittgenstein but also Wallace Stevens, Cormac McCarthy as well as Roland Barthes, this cache of incidental remarks eschews what’s granular for the biggest picture available, leaving below the hyper-specialized fields of academia for a bird’s-eye view of their crop circles. Obiter Dicta is an unapologetic experiment in intellectual dot-connecting that challenges much long-standing wisdom about everything from illuminated manuscripts to Minecraft and the evolution of European music with lyrical brevity; that is, before jumping to the next topic.

Emulating a shingled write disk

Shingled Magnetic Recording technology is expected to play a major role in the next generation of hard disk drives. But it introduces some unique challenges to system software researchers and prototype hardware is not readily available for the broader research community. It is crucial to work on system software in parallel to hardware manufacturing, to ensure successful and effective adoption of this technology. In this work, we present a novel Shingled Write Disk (SWD) emulator that uses a hard disk utilizing traditional Perpendicular Magnetic Recording (PMR) and emulates a Shingled Write Disk on top of it. We implemented the emulator as a pseudo block device driver and evaluated the performance overhead incurred by employing the emulator. The emulator has a slight overhead which is only measurable during pure sequential reads and writes. The moment disk head movement comes into picture, due to any random access, the emulator overhead becomes so insignificant as to become immeasurable. © 2012 IEEE