Exploiting Inter- and Intra-Memory Asymmetries for Data Mapping in Hybrid Tiered-Memories

Modern computing systems are embracing hybrid memory comprising of DRAM and non-volatile memory (NVM) to combine the best properties of both memory technologies, achieving low latency, high reliability, and high density. A prominent characteristic of DRAM-NVM hybrid memory is that it has NVM access latency much higher than DRAM access latency. We call this inter-memory asymmetry. We observe that parasitic components on a long bitline are a major source of high latency in both DRAM and NVM, and a significant factor contributing to high-voltage operations in NVM, which impact their reliability. We propose an architectural change, where each long bitline in DRAM and NVM is split into two segments by an isolation transistor. One segment can be accessed with lower latency and operating voltage than the other. By introducing tiers, we enable non-uniform accesses within each memory type (which we call intra-memory asymmetry), leading to performance and reliability trade-offs in DRAM-NVM hybrid memory. We extend existing NVM-DRAM OS in three ways. First, we exploit both inter- and intra-memory asymmetries to allocate and migrate memory pages between the tiers in DRAM and NVM. Second, we improve the OS's page allocation decisions by predicting the access intensity of a newly-referenced memory page in a program and placing it to a matching tier during its initial allocation. This minimizes page migrations during program execution, lowering the performance overhead. Third, we propose a solution to migrate pages between the tiers of the same memory without transferring data over the memory channel, minimizing channel occupancy and improving performance. Our overall approach, which we call MNEME, to enable and exploit asymmetries in DRAM-NVM hybrid tiered memory improves both performance and reliability for both single-core and multi-programmed workloads.Comment: 15 pages, 29 figures, accepted at ACM SIGPLAN International Symposium on Memory Managemen

Road to 2023: our common agenda and the pact for the future

Fears of rising conflict, new COVID-19 variants, irreversible climate change, and eroding collaboration in the global economy threaten to undermine the 2030 Agenda for Sustainable Development and other efforts to advance human progress. Yet, a once-in-a-generation opportunity to review and dramatically improve global tools for managing such enormous challenges, a Summit of the Future, is under serious consideration for September 2023 by the United Nations’ 193 Member States. Informed by research and policy dialogues—initially undertaken for the Albright-Gambari Commission and its follow-through, and most recently to help flesh out key proposals in the Secretary-General’s seminal report, Our Common Agenda—this report’s twenty main recommendations are intended to encourage more ambitious, forward-looking thinking and deliberation on global governance renewal and innovation in the run-up to next year’s Summit.FdR – Publicaties niet-programma gebonde

Grounds for engagement: Dissonances and overlaps at the intersection of contemporary civilizations analysis and postcolonial sociology

This article elucidates grounds for engagement between two fields of the social sciences engaged in critique of Eurocentrism: contemporary civilizations analysis and postcolonial sociology. Between the two fields there are both evident dissonances and points of potential dialogue and engagement. The article identifies three areas of high contention: divergent perceptions of essentialism, commitments to transformative politics and evaluations of the paradigm of multiple modernities. Despite extensive theoretical and normative differences, a notional intersection of the two fields is outlined in the form of three conceptual and methodological shifts. The first is a displacement of ideal typology. The second move is the most original. ‘Intercivilizational encounters’ and ‘intracivilizational encounters’ are re-cast as ‘intercivilizational engagement’. The goal is the demarcation of a discrete position based on a strong version of interaction that goes further than the notion of intercivilizational encounters recently re-developed in civilizational analysis. To illustrate potential grounds for engagement on this point, the article reviews the historiography of ‘connected histories’ and the insights of relational historians. Finally, the article urges for a nuanced definition of ‘region’ and deeper appreciation of the multiplicity of regionalisms as a meeting point for both fields of critique of Eurocentrism

Comparative historical sociology and the State : problems of method

Historical sociology can be understood both as a specific sub-field of sociology and as providing general conceptual underpinnings of the discipline, to the extent that it provides an understanding of the specificity of the modern state and the perceived emergence of modernity within Europe. The association of modernity with Europe (and with a European history limited to the self-identified boundaries of the continent) is commonplace and pervasive within the social sciences and humanities. What such an understanding fails to take into consideration, however, are the connections between Europe and the rest of the world that constitute the broader context for the emergence of what is understood to be the modern world and its institutions, such as the state and market. In this article, I suggest that integral to this misunderstanding, and its reproduction over time, is the methodology of comparative historical sociology as represented by ideal types. In contrast, I argue for ‘connected sociologies’ as a more appropriate way to understand our shared past and its continuing impact upon the present. I examine these issues in the context of historical sociological understandings of nation-state formation

Different paths to the modern state in Europe: the interaction between domestic political economy and interstate competition

Theoretical work on state formation and capacity has focused mostly on early modern Europe and on the experience of western European states during this period. While a number of European states monopolized domestic tax collection and achieved gains in state capacity during the early modern era, for others revenues stagnated or even declined, and these variations motivated alternative hypotheses for determinants of fiscal and state capacity. In this study we test the basic hypotheses in the existing literature making use of the large date set we have compiled for all of the leading states across the continent. We find strong empirical support for two prevailing threads in the literature, arguing respectively that interstate wars and changes in economic structure towards an urbanized economy had positive fiscal impact. Regarding the main point of contention in the theoretical literature, whether it was representative or authoritarian political regimes that facilitated the gains in fiscal capacity, we do not find conclusive evidence that one performed better than the other. Instead, the empirical evidence we have gathered lends supports to the hypothesis that when under pressure of war, the fiscal performance of representative regimes was better in the more urbanized-commercial economies and the fiscal performance of authoritarian regimes was better in rural-agrarian economie

Aging-Aware Request Scheduling for Non-Volatile Main Memory

Modern computing systems are embracing non-volatile memory (NVM) to implement high-capacity and low-cost main memory. Elevated operating voltages of NVM accelerate the aging of CMOS transistors in the peripheral circuitry of each memory bank. Aggressive device scaling increases power density and temperature, which further accelerates aging, challenging the reliable operation of NVM-based main memory. We propose HEBE, an architectural technique to mitigate the circuit aging-related problems of NVM-based main memory. HEBE is built on three contributions. First, we propose a new analytical model that can dynamically track the aging in the peripheral circuitry of each memory bank based on the bank's utilization. Second, we develop an intelligent memory request scheduler that exploits this aging model at run time to de-stress the peripheral circuitry of a memory bank only when its aging exceeds a critical threshold. Third, we introduce an isolation transistor to decouple parts of a peripheral circuit operating at different voltages, allowing the decoupled logic blocks to undergo long-latency de-stress operations independently and off the critical path of memory read and write accesses, improving performance. We evaluate HEBE with workloads from the SPEC CPU2017 Benchmark suite. Our results show that HEBE significantly improves both performance and lifetime of NVM-based main memory.Comment: To appear in ASP-DAC 202

A África, o Sul e as ciências sociais brasileiras : descolonização e abertura

O texto introduz questões recentes sobre a relação entre as ciências sociais na África e no Brasil, inserindo-as no debate sobre as sociologias do Sul e a geopolítica do conhecimento na produção de teoria social. A partir da noção de sociologia não exemplar são apresentados alguns dos possíveis caminhos teórico-metodológicos que possibilitariam um posicionamento mais simétrico para a produção de conhecimento localizada fora da Euro-América.The paper introduces the contemporary debates on the relation of social sciences in Africa and Brazil by framing them both under the current discussion about the "sociologies of the south" and the ones on "the geopolitics of knowledge". Deploying the notion of a "non-exemplary sociology", I seek to present some possible theoretical and methodological ways that would enable a more symmetric positioning of the knowledge produced outside the Euro-America