6 research outputs found

    A Frugal Approach to Reduce RCU Grace Period Overhead

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    Grace period computation is a core part of the Read-Copy-Update (RCU) synchronization technique that determines the safe time to reclaim the deferred objects' memory. We first show that the eager grace period computation employed in the Linux kernel is appropriate only for enterprise workloads such as web and database servers where a large amount of reclaimable memory awaits the completion of a grace period. However, such memory is negligible in High-Performance Computing (HPC) and mostly idling environments due to limited OS kernel activity. Hence an eager approach is not only futile but also detrimental as the CPU cycles consumed to compute a grace period leads to jitter in HPC and frequent CPU wake-ups in idle environments. We design frugal grace periods, an economical grace period computation for non-enterprise environments that consume fewer CPU cycles. In addition, we reduce the number of grace periods either by using heuristics or by letting the memory allocator to explicitly request for a grace period only when it is running out of free objects. Our implementation in the Linux kernel reduces the number of grace periods by 68% to 99%, reduces the CPU time consumed by grace periods by 39% to 99%, improves the throughput by up to 28% for NAS parallel benchmarks and increases the CPU time spent in low power states by 2.4x when the system is idle

    The Murray Ledger and Times, September 7, 1996

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    The torch and the sword : a history of the army cadet movement in Australia 1866-2004

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    The aim of this thesis is to provide a general history of the army cadet movement in Australia from 1866 to 2004 by tracing the interactions between four fundamental forces that have stood as its foundation for almost 140 years. In various guises military, educational, social, and financial factors are the pillars on which the cadet movement has always rested. Over time the balance and relative dominance of each has determined the shape and state of the cadet organisation and will continue to do so in the future. When these four forces have been aligned the movement has thrived but when they have pulled in disparate directions it has faltered. Throughout the thesis, contextualising these four key concepts, are two more general themes concerning the influence of conservative politics and a recurring state school/private school divide. The history of army cadets, and therefore this thesis, is an investigation into the interplay of these dynamics. With such a purpose and methodology the thesis begins by tracing the development of the movement from its nineteenth century origins by identifying issues and circumstances that led some colonies to maintain thousands of cadets while others struggled to field any. It goes on to examine the formation, five years after Federation, of a Commonwealth cadet scheme birthed only to be swamped by the era of compulsory military training in Australia from 1911-29 which saw, at its peak, almost 100,000 schoolboys in khaki. The thesis analyses the re-organised voluntary cadet system in place from 1930-38 which, matching the circumstances of the adult army, faltered in numbers and support as it was restructured into dual 'Regimental' and 'School' branches. It goes on to assess the impact of the Second World War and the renewed impetus it provided to the cadet organisation before investigating the prosperity of the movement throughout the 1950s and 1960s in spite of the complexities raised by National Service and Australian involvement in conflicts in Korea, Vietnam, Malaya and Borneo. Particular attention is paid to the early 1970s and the machinations surrounding the unexpected decision to disband the cadet organisation announced by the Labor government on 26 August 1975. The cadet story does not conclude at this point, however, with Vice Regal controversy and a subsequent Liberal-National election victory resurrecting the movement. The re-styled cadet scheme of 1976-83 is investigated followed by twelve years of division and distress under consecutive Labor federal governments between 1984-95. The thesis concludes by examining the reversal of fortunes for the movement from 1996-2004 which saw the cadet system develop, by the end of the period, into a well led, resourced and motivated organisation of almost 17,000 members. The research informing this thesis is based on documents held in National Archives of Australia offices in all state capitals, as well as those held in the Australian War Memorial. In addition, all state public record offices have yielded significant material, as have a wide range of private and school-based archives. More recent primary source information has been gathered from sources within the Department of Defence Archives, Queanbeyan, NSW, while select active and closed files from Headquarters Australian Army Cadets and the Directorate of Defence Force Cadets were graciously provided to the author. The study has also been informed by a wide selection of official, privately published and unpublished secondary sources spanning more than a century

    Courier Gazette : July 5, 1898

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    A paradox of knowing : teachers' knowing about students.

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    Thesis (Ph.D.) - University of KwaZulu-Natal, 2008.This study is a critical exploration and post-structural explanation of how and what teachers ' know about students. The intention has been to explore teachers' knowing beyond taken-for-granted iterations, beliefs and conceptions of those they teach and to theorise the nature of teachers' knowing. The route to insight involved deploying critical ethnography to produce data over a six-month period. The study site, a secondary school I named Amethyst, is an apartheid-era creation. Since 1990, political change has introduced uncertainties of various sorts and has destabilised the ethos and culture of the school: conflicts between teachers and students, conflicts amongst students' peers, students' participation in activities that are unacceptable and harmful, severe lack of funds to meet the financial needs of the school and lack of human and teaching resources. It is within such an uncertain space that I produced data to interrogate teachers ' knowing about students. At the site, data production was impeded by various confounding factors that eroded trust between the participants and me (the researcher). Traditionally, an ethnographic approach entails three kinds of observation: descriptive observations at the beginning, followed by focused observations narrowed to the concerns of the study and finally, selective observations to consolidate focused observations. For the data production process to continue, the researcher-researched relationship had to be assessed and reconfigured from a critical perspective. In this study the above-mentioned observations have been renamed and reconceptualised from participants' perspectives as: an innocuous phase, an invasive phase and a reciprocity phase. Furthermore, an explication is provided of how research reflexivity shaped the reconceptualisation and the data production processes. Usual forms of data production were abandoned and replaced by a conscious effort to reveal my story to participants eventuating in the form of an exchange of data - my story for their stories. Reciprocal participation enabled data production to be completed and two sets of data were generated: teachers ' stories and students ' stories. Eight teachers ' stories derived from teachers' to teachers' students' teachers' interviews were woven into texts whilst fourteen students' autobiographical accounts comprising lived ex peri ences were re-presented as they narrated them. Juxtapos ing stud ents' accounts with teachers' knowing has yielded three revelations. Firstly, unveil ing how teachers constitute students through knowing them in particul ar ways. Second ly, it reveals how students' constitution as subjects at home and at school a llow them to be known in parti cular ways and thirdl y, revealing the ways students consc iously prevent teachers from knowing about their li ved ex peri ences. The analyses of both sets of stories have dee pened understanding of teachers' knowing, taking it beyond teachers' persona l be lief systems. Plac ing both sets of data und er a criti cal gaze has yie lded three ways of teacher knowing (so li cited, un solic ited and common) and fi ve kind s of teacher knowing (rac ia li sed, gendered, cultu ra l, c lassed, and profess ional). From th e analyses, I have inferred that teachers' knowing about students, when j uxtaposed with and med iated by students' li ved experi ences, is flawed, incomplete, parti al, complex, contradictory, and uni-dimens ional. I put fo rward a th es is predicated on two abstractions from th e anal yses: one, that teachers ' knowing is dangerous because it prope ls teachers towards act ions that can result in d isastrous consequences for students; and two, that not knowing is use ful because it is a more criti ca lly and soc ia lly j ust approach to teaching as it a llows teachers to functi on without succumbing to marginali sing the non-traumati sed and those without chall enges at the persona l level. In effect it tran slates into practices that treat all students equally in an academic settin g, so that in one in stantiati on, students are dri ven to stri ve for academic ac hievement in stead of focusing on emotiona lly debilitating di stractions th at cannot be resolved by teachers' knowing, understanding, and empathy. Not knowing, I argue, offers viable poss ibilities for working with students whose li ves are compromised by low socioeconomic cond iti ons and pro bl ematic family re lati ons. This in vers ion of common-sense instincts about teachers ' knowing and not knowing IS theorised by deploying a topologica l metaphor, the Mii bius strip, to demonstrate that teachers' knowing and not knowing about stud ents are not polar oppos ites on a continuum, but are paradoxically, cohabitants of a common space, refl ections of each other, res iding in each other. Additiona lly, I charge that teachin g and caring, mediated by knowing, form the foundation of teachers' work, and argue that at Amethyst, teaching and caring cannot be activated simul ta neo us ly within an indi vidual teacher. Kcy words: critica l ethnography, teachers' knowing, paradox of knowin g
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