STT-MRAM for real-time embedded systems: performance and WCET implications

STT-MRAM is an emerging non-volatile memory quickly approaching DRAM in terms of capacity, frequency and device size. Intensified efforts in STT-MRAM research by the memory manufacturers may indicate a revolution with STT-MRAM memory technology is imminent, and therefore it is essential to perform system level research to explore use-cases and identify computing domains that could benefit from this technology. Special STT-MRAM features such as intrinsic radiation hardness, non-volatility, zero stand-by power and capability to function in extreme temperatures makes it particularly suitable for aerospace, avionics and automotive applications. Such applications often have real-time requirements --- that is, certain tasks must complete within a strict deadline. Analyzing whether this deadline is met requires Worst Case Execution Time (WCET) Analysis, which is a fundamental part of evaluating any real-time system. In this study, we investigate the feasibility of using STT-MRAM in real-time embedded systems by analyzing average system performance impact and WCET implications.This work was supported by BSC, Spanish Government through Programa Severo Ochoa (SEV-2015-0493), by the Spanish Ministry of Science and Technology through TIN2015-65316-P project and by the Generalitat de Catalunya (contracts 2014-SGR-1051 and 2014-SGR-1272). This work has also received funding from the European Union’s Horizon 2020 research and innovation programme under ExaNoDe project (grant agreement No 671578). Jaume Abella was partially supported by the Ministry of Economy and Competitive-ness under Ramon y Cajal postdoctoral fellowship RYC-2013-14717.Peer ReviewedPostprint (author's final draft

Energy-Aware Opcode Design

Abstract-Embedded processors are required to achieve high performance while running on batteries. Thus, they must exploit all the possible means available to reduce energy consumption while not sacrificing performance. In this work, one technique to reduce energy is explored to intelligently design the instructionopcodes of a processor based on a target-workload. The optimization is done using a heuristic that not-only minimizes switching between adjacent instructions, but also simplifies the decoding to reduce latches to save dynamic energy. On average, an optimized opcode is able to be decoded using 40-60% less latches in the decoder. In addition, it is shown that a decoder optimized for algorithms that had similar program structure, similar data-types or similar behavior exhibited consistent patterns of energy reduction. The techniques presented in this paper yield an average 10% reduction in the total dynamic energy. It is also shown that this heuristic can be used to achieve similar results on different issue-width processors. I. MOTIVATION Embedded devices are required to perform several complex tasks that were once attempted by high-performance systems One solution is to take a general-purpose processor and customize it for an embedded system [1]. These embedded processors are simpler than their high-performance counterparts and require significant assistance from the compiler for scheduling, branch-handling etc. However, unlike high-performance systems, wide-availability of compilers, assemblers, and other utilities are limited The first logical step for designing (or choosing) such processors is to define the target application. This ONE target application represents the main workload of this processor. It is generally a good assumption that this target application is one of the most frequently executed applications in this system. If this one target application is able to be run at high performance while consuming less energy, then the overall system energy is reduced. The main concentration of this work is to provide a heuristic for intelligent-design of the instruction opcodes for an embedded processor using one application as the target (or training application). The new-opcode configuration is created by analyzing the code-generator and reducing switching among the adjacent instructions occurring in the target application. The opcodes are designed such that frequently occurring instructions are decoded easily, which reduces the internal decoder power. Unlike previous work, which requires the superset of all benchmarks to be run on the processor to gain any power/energy reduction ( [9] [29]), we prove that one benchmark is enough to provide a significant amount of energy reduction. In addition, we show that an energyefficient opcode-design can reduce energy in the decoder and other stages of the pipelined processor. Finally, we show the effects of processor issue-width scaling on the overall power reduction using this methodology. For this work, the compiler is selected and designed before the processor. Using this design approach, the constraints imposed by the compiler (as shown in section 2) is known ahead of time, and the processor can be designed accordingly. The paper is organized as follows. The related works are explained in section 2. Section 3 gives a brief introduction of a Retargetable code-generator. The experimental framework and the benchmark-set are explained in section 4. Section 5 explains the project methodology. The discussion of results is given in section 6 and the paper is concluded in section 7. II. RELATED WORK Several works have been proposed for power and energy reduction using intelligent opcode-design. To our knowledge, the only work that closely resembles ours is by Benini et al. Cheng and Tyso

AMEG: the new SETAC advisory group on aquatic macrophyte ecotoxicology

Introduction and background Primary producers play critical structural and functional roles in aquatic ecosystems; therefore, it is imperative that the potential risks of toxicants to aquatic plants are adequately assessed in the risk assessment of chemicals. The standard required macrophyte test species is the floating (non-sediment-rooted) duckweed Lemna spp. This macrophyte species might not be representative of all floating, rooted, emergent, and submerged macrophyte species because of differences in the duration and mode of exposure; sensitivity to the specific toxic mode of action of the chemical; and species-specific traits (e.g., duckweed's very short generation time). Discussion and perspectives These topics were addressed during the workshop entitled “Aquatic Macrophyte Risk Assessment for Pesticides” (AMRAP) where a risk assessment scheme for aquatic macrophytes was proposed. Four working groups evolved from this workshop and were charged with the task of developing Tier 1 and higher-tier aquatic macrophyte risk assessment procedures. Subsequently, a SETAC Advisory Group, the Macrophyte Ecotoxicology Group (AMEG) was formed as an umbrella organization for various macrophyte working groups. The purpose of AMEG is to provide scientifically based guidance in all aspects of aquatic macrophyte testing in the laboratory and field, including prospective as well as retrospective risk assessments for chemicals. As AMEG expands, it will begin to address new topics including bioremediation and sustainable management of aquatic macrophytes in the context of ecosystem services

Women write the rights of woman: The sexual politics of the personal pronoun in the 1790s

This article investigates patterns of personal pronoun usage in four texts written by women about women's rights during the 1790s: Mary Wollstonecraft's A Vindication of the Rights of Woman (1792), Mary Hays' An Appeal to the Men of Great Britain (1798), Mary Robinson's Letter to the Women of England (1799) and Mary Anne Radcliffe's The Female Advocate (1799). I begin by showing that at the time these texts were written there was a widespread assumption that both writers and readers of political pamphlets were, by default, male. As such, I argue, writing to women as a woman was distinctly problematic, not least because these default assumptions meant that even apparently gender-neutral pronouns such as I, we and you were in fact covertly gendered. I use the textual analysis programme WordSmith to identify the personal pronouns in my four texts, and discuss my results both quantitatively and qualitatively. I find that while one of my texts does little to disturb gender expectations through its deployment of personal pronouns, the other three all use personal pronouns that disrupt eighteenth century expectations about default male authorship and readership. Copyright © 2007 SAGE Publications

“Influence” In historical explanation: Mary morgan’s traveling facts and the context of influence

In my years as a student of Mary Morgan and later as her junior peer, I observed that one concept prompted her to react with caution and skepticism. That common notion was “influence.” In this chapter, I follow her cues to ask what are the legitimate grounds for claims of influence in historical explanation. Morgan’s writings have made us aware that the story of social science cannot be captured in simple reckonings of influence, and that long chains of actions are required to seat an idea in the mind, and longer still to set it to paper. My contribution to problematizing influence is to list the pitfalls of its uncritical use but also, once suitably redefined, its potential contribution to analysis. To illustrate my claims, I propose a test case, to study the “influence of Mary Morgan.

Natational Dress: Functionality, Fashion and the Fracturing of Separate Spheres in Victorian Britain

In 1873, The Englishwoman's Domestic Magazine extolled the values of swimming for women and gave advice on the best form of bathing dress, one which preserved modesty and met the demands of contemporary fashion. This essentially impractical type of bathing outfit has been the subject of much of the historiography surrounding female swimming costumes but it was not the only swimming dress on show during the “long” Victorian period. The women of all classes who participated in more serious swimming required something functional rather than fashionable while working-class professional natationists, who appeared regularly in water shows throughout the country, wore attire that combined functionality, tight to the body while allowing freedom of movement, with public appeal, a critical consideration for female exhibitors. Their activities and costumes challenged prevailing notions of “separate spheres” and this paper explores Victorian aquatic dress in the context of class, gender and social space

Biggish Data: Friedrich Engels, Material Ecology, and Victorian Data

Through Friedrich Engels’ The Condition of the Working Class in England (1845), this article examines two prominent themes in environmental humanities – vital ecological materialism and ‘big data’. Engels’ vivid descriptions of factories, houses, and environment shared the central tenets of ‘material ecology’ – ‘thing power’ (Jane Bennett); ‘intra-actions’ of social and material agency (Karen Barad); ‘trans-corporeality’ (Stacy Alaimo) – and met Bennett’s call to align vital and historical materialism. The main body of the paper connects his analysis both to current debates about integrating ‘big data’ into social science and the humanities and to comparable nineteenth-century developments in statistics and data visualisation. Engels articulated the working-class condition by blending four distinct modes of investigation: big data; qualitative survey research; literary thick description; and theory (the nascent critique of capitalist political economy). Such a mix remains rich with possibilities for sociology and humanities not only in communicating but in generating knowledge about complex ecologies

Law, Environment, and the “Nondismal” Social Sciences

Over the past 30 years, the influence of economics over the study of environmental law and policy has expanded considerably, becoming in the process the predominant framework for analyzing regulations that address pollution, natural resource use, and other environmental issues. This review seeks to complement the expansion of economic reasoning and methodology within the field of environmental law and policy by identifying insights to be gleaned from various “nondismal” social sciences. In particular, three areas of inquiry are highlighted as illustrative of interdisciplinary work that might help to complement law and economics and, in some cases, compensate for it: the study of how human individuals perceive, judge, and decide; the observation and interpretation of how knowledge schemes are created, used, and regulated; and the analysis of how states and other actors coordinate through international and global regulatory regimes. The hope is to provide some examples of how environmental law and policy research can be improved by deeper and more diverse engagement with social science

Gender Monstrosity

Deadgirl (2008) is based around a group of male teens discovering and claiming ownership of a bound female zombie, using her as a sex slave. This narrative premise raises numerous tensions that are particularly amplified by using a zombie as the film’s central victim. The Deadgirl is sexually passive yet monstrous, reifying the horrors associated with the female body in patriarchal discourses. She is objectified on the basis of her gender, and this has led many reviewers to dismiss the film as misogynistic Torture Porn. However, the conditions under which masculinity is formed here – where adolescent males become "men" by enacting sexual violence – are as problematic as the specter of the female zombie. Deadgirl is clearly horrific and provocative: in this article I seek to probe implications arising from the film’s gender conflicts