RHmalloc : a very large, highly concurrent dynamic memory manager

University of Technology, Sydney. Dept. of Software Engineering.Dynamic memory management (DMM) is a fundamental aspect of computing, directly affecting the capability, performance and reliability of virtually every system in existence today. Yet oddly, the fifty year research into DMM has not taken memory capacity into account, having fallen significantly behind hardware trends. Comparatively little research work on scalable DMM has been conducted – of the order of ten papers exist on this topic – all of which focus on CPU scalability only; the largest heap reported in the literature to date is 600MB. By contrast, symmetric multiprocessor (SMP) machines with terabytes of memory are now commercially available. The contribution of our research is the formal exploration, design, construction and proof of a general purpose, high performance dynamic memory manager which scales indefinitely with respect to both CPU and memory – one that can predictably manage a heap of arbitrary size, on any SMP machine with an arbitrary number of CPU’s, without a priori knowledge. We begin by recognizing the scattered, inconsistency of the literature surrounding this topic. Firstly, to ensure clarity, we present a simplified introduction, followed by a catalog of the fundamental techniques. We discuss the melting pot of engineering tradeoffs, so as to establish a sound basis to tackle the issue at hand – large scale DMM. We review both the history and state of the art, from which significant insight into this topic is to be found. We then explore the problem space and suggest a workable solution. Our proposal, known as RHmalloc, is based on the novel perspective that, a highly scalable heap can be viewed as, an unbounded set of finite-sized sub-heaps, where each sub-heap maybe concurrently shared by any number of threads; such that a suitable sub-heap can be found in O(1) time, and an allocation from a suitable sub-heap is also O(1). Testing the design properties of RHmalloc, we show by extrapolation that, RHmalloc will scale to at least 1,024 CPU’s and 1PB; and we theoretically prove that DMM scales indefinitely with respect to both CPU and memory. Most importantly, the approach for the scalability proof alludes to a general analysis and design technique for systems of this nature

Two Forms of Realism. Making Sense of Rorty's Controversy with Brandom and Ramberg over Objectivity

There is a famous puzzle in Rorty scholarship: Did or did Rorty not subscribe to a form of realism and truth when he made concessions regarding objectivity to Bj\uf8rn Ramberg in 2000? Relatedly, why did Rorty agree with Ramberg but nevertheless insist upon disagreeing with Brandom, though large parts of the research community hold their two respective requests for shifts in Rorty\u2019s stance to be congruous? The present article takes up the discussion and tries, for the first time, to make sense of Rorty\u2019s insistence that there is a difference between Brandom\u2019s notion of \u201cmade true by facts\u201d and Ramberg\u2019s notion of \u201cgetting things right\u201d by showing that Ramberg\u2019s appropriateness-conditions are fully compatible with Rorty\u2019s revised interpretation of Davidson\u2019s concept of \u201ctriangulation,\u201d whereas Brandom\u2019s inferential \u201cmade-true-by-facts\u201d-language game is not. The reason why Rorty agrees with Ramberg but not with Brandom, I argue, is that Brandom\u2019s contemporary concept of objectivity, as developed in his contribution to the debate and in his Making It Explicit, works with a scheme-content distinction, whereas Ramberg\u2019s Davidson-based version does not. As many of his critics suppose, Rorty\u2019s concession to Ramberg entails a substantive revision of Rorty\u2019s position, not just a clarification. However, this new position is not in conflict with Rorty\u2019s most important commitment, namely his anti-authoritarianism. The revised account still does not bind him to the forms of realism and truth that his critics favor. The article explains to which forms of realism and truth Rorty\u2019s concessions to Ramberg commit him instead

Consistency of Probability Measure Quantization by Means of Power Repulsion–Attraction Potentials

This paper is concerned with the study of the consistency of a variational method for probability measure quantization, deterministically realized by means of a minimizing principle, balancing power repulsion and attraction potentials. The proof of consistency is based on the construction of a target energy functional whose unique minimizer is actually the given probability measure ωω to be quantized. Then we show that the discrete functionals, defining the discrete quantizers as their minimizers, actually Γ-converge to the target energy with respect to the narrow topology on the space of probability measures. A key ingredient is the reformulation of the target functional by means of a Fourier representation, which extends the characterization of conditionally positive semi-definite functions from points in generic position to probability measures. As a byproduct of the Fourier representation, we also obtain compactness of sublevels of the target energy in terms of uniform moment bounds, which already found applications in the asymptotic analysis of corresponding gradient flows. To model situations where the given probability is affected by noise, we further consider a modified energy, with the addition of a regularizing total variation term and we investigate again its point mass approximations in terms of Γ-convergence. We show that such a discrete measure representation of the total variation can be interpreted as an additional nonlinear potential, repulsive at a short range, attractive at a medium range, and at a long range not having effect, promoting a uniform distribution of the point masses.Austrian Science Fund (START project

Carbon Concentration Dependence of the Superconducting Transition Temperature and Structure of MgCxNi3

The crystal structure of the superconductor MgCxNi3 is reported as a function of carbon concentration determined by powder neutron diffraction. The single-phase perovskite structure was found in only a narrow range of carbon content, 0.88 < x < 1.0. The superconducting transition temperature was found to decrease systematically with decreasing carbon concentration. The introduction of carbon vacancies has a significant effect on the positions of the Ni atoms. No evidence for long range magnetic ordering was seen by neutron diffraction for carbon stoichiometries within the perovskite phase stability range.Comment: 4 figure

Empatia e giustizia nella ricezione artistica dei casi e del processo intorno al terrorismo nero in Germania

L’articolo analizza il motivo della giustizia nel film Oltre la notte (2017) di Fatih Akin. Il film tematizza la ‘giustizia’ su due livelli: uno, il film crea per la prima volta dopo la serie di omicidi commessi dal Nsu in Germania empatia per le vittime e le loro famiglie, rendendo così giustizia alla sofferenza delle vittime, e due, il film mette in scena i conflitti che nascono in un mondo post-metafisico fra la dimensione della giustizia e l’agency del soggetto moderno. Dato che il film è uscito prima dell’esito del processo reale ai membri del Nsu, può anche essere letto, tramite l’uso degli strumenti del campo di studi del Law and Literature, come contribu-to al tessuto normativo con il quale si valuta l’esito del processo reale

Analytical Physical Model for Organic Metal-Electrolyte-Semiconductor Capacitors

This work presents the analytical physical modeling of undoped organic metal-electrolyte-semiconductor (OMES) capacitors in the framework of the Nernst-Planck-Poisson theory, including the presence of compact interfacial layers. This work derives an exact analytical solution, up to a quadrature, for the stationary electric potential and charge density distributions in both the semiconductor film and the electrolyte solution, and from them the sheet semiconductor charge and the stationary differential capacitance are obtained as a function of the applied voltage. The dependence of these magnitudes on the physical device parameters, like the ionic concentration of the electrolyte, the capacitance of the interfacial compact layers and the injected hole density is then analyzed. This work shows that ionic diffusive effects in the electrolyte can play an important role in the device response, inducing a broadening of the transition from the weak to the strong accumulation regimes. This fact can make that the strong accumulation regime is not achieved in OMES within the usual voltage operation range of these devices. The analytical solution is validated by means of finite element numerical calculations. The implications of the results obtained on the physics of electrolyte gated organic field effect transistors (EGOFETs) are discussed

Dental Students’ Evaluations of Practice Management Education and Interest in Business‐Related Training: Exploring Attitudes Towards DDS/DMD‐MBA Programs

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153586/1/jddjde018139.pd