A case for (partially) tagged geometric history length branch prediction

International audienceIt is now widely admitted that in order to provide state-of-the-art accuracy, a conditional branch predictor must combine several predictions. Recent research has shown that an adder tree is a very effective approach for the prediction combination function. In this paper, we present a more cost effective solution for this prediction combination function for predictors relying on several predictor components indexed with different history lengths. Using geometric history length as the O-GEHL predictor, the TAGE predictor uses (partially) tagged components as the PPM-like predictor. TAGE relies on (partial) hit-miss detection as the prediction computation function. TAGE provides state-of-the-art prediction accuracy on conditional branches. In particular, at equivalent storage budgets, the TAGE predictor significantly outperforms all the predictors that were presented at the Championship Branch Prediction in december 2004. The accuracy of the prediction of the targets of indirect branches is a major issue on some applications. We show that the principles of the TAGE predictor can be directly applied to the prediction of indirect branches. The ITTAGE predictor (Indirect Target TAgged GEometric history length) significantly outperforms previous state-of-the-art indirect target branch predictors. Both TAGE and ITTAGE predictors feature tagged predictor components indexed with distinct history lengths forming a geometric series. They can be associated in a single cost-effective predictor, sharing tables and predictor logic, the COTTAGE predictor (COnditional and indirect Target TAgged GEometric history length)

Principled Approaches to Last-Level Cache Management

Memory is a critical component of all computing systems. It represents a fundamental performance and energy bottleneck. Ideally, memory aspects such as energy cost, performance, and the cost of implementing management techniques would scale together with the size of all different computing systems; unfortunately this is not the case. With the upcoming trends in applications, new memory technologies, etc., scaling becomes a bigger a problem, aggravating the performance bottleneck that memory represents. A memory hierarchy was proposed to alleviate the problem. Each level in the hierarchy tends to have a decreasing cost per bit, an increased capacity, and a higher access time compared to its previous level. Preferably all data will be stored in the fastest level of memory, unfortunately, faster memory technologies tend to be associated with a higher manufacturing cost, which often limits their capacity. The design challenge is, to determine which is the frequently used data, and store it in the faster levels of memory. A cache is a small, fast, on-chip chunk of memory. Any data stored in main memory can be stored in the cache. For many programs, a typical behavior is to access data that has been accessed previously. Taking advantage of this behavior, a copy of frequently accessed data is kept in the cache, in order to provide a faster access time next time is requested. Due to capacity constrains, it is likely that all of the frequently reused data cannot fit in the cache, because of this, cache management policies decide which data is to be kept in the cache, and which in other levels of the memory hierarchy. Under an efficient cache management policy, an encouraging amount of memory requests will be serviced from a fast on-chip cache. The disparity in access latency between the last-level cache and main memory motivates the search for efficient cache management policies. There is a great amount of recently proposed work that strives to utilize cache capacity in the most favorable to performance way possible. Related work focus on optimizing the performance of caches focusing on different possible solutions, e.g. reduce miss rate, consume less power, reducing storage overhead, reduce access latency, etc. Our work focus on improving the performance of last-level caches by designing policies based on principles adapted from other areas of interest. In this dissertation, we focus on several aspects of cache management policies, we first introduce a space-efficient placement and promotion policy which goal is to minimize the updates to the replacement policy state on each cache access. We further introduce a mechanism that predicts whether a block in the cache will be reused, it feeds different features from a block to the predictor in order to increase the correlation of a previous access to a future access. We later introduce a technique that tweaks traditional cache indexing, providing fast accesses to a vast majority of requests in the presence of a slow access memory technology such as DRAM

Changes in the nature and governance of public spaces in the historic city centre : the case of Damascus

Public space is a component of our physical environment which has an important role in city life. This thesis is primarily about investigating public space and public realm in the historic city centre of Damascus in order to understand the potential for its improvement, and secondarily about recommending specific actions towards this. The research takes a qualitative approach focusing on public space as a ‘product’ which is the result of a process. In terms of the product, the nature, morphological and functional aspects of public spaces in Damascus are examined. The governance process is analysed at local level to define main actors, the rules they interact with and the rationalities they use to intervene in public space. This analysis includes locality-specific literature review and interviews with key informants. Such case study analysis is undertaken against the background of a survey of public space regeneration in selected cities around the Mediterranean. Public spaces in Damascus historically developed under strong endogenous social and cultural rules creating a hierarchy of ‘traditional’ spaces which supported public, parochial and private realms. In the contemporary period, these spaces have gone through modernisation in their governance process through introducing new actors and more formal rules, which have led to more ‘publicness’ and tension between tradition and modernisation. This has affected their nature as well as morphological and functional aspects. Analysis showed that strong centralised political and public sector control is found over the governance process through a top-down representative approach. Capacities, interests and perception of public spaces among actors, in addition to poor management, strict legislation and lack of qualified cadres, have all contributed to the continuing deteriorating situation of public spaces. Moreover, interventions for improvement occurred on a short-term basis and mainly to restore historical monuments and improve traffic. An integrated approach to upgrading open spaces is still needed on a long term basis, subject to the available financial resources, with wider governance arrangements and further collaboration and integration between different governmental bodies

Urban Street Networks and Sustainable Transportation

Urban street space is challenged with a variety of emerging usages and users, such as various vehicles with different speeds, passenger pick-up and drop-off by mobility services, increasing parking demand for a variety of private and shared vehicles, new powertrains (e.g., charging units), and new vehicles and services fueled by digitalization and vehicle automation. These new usages compete with established functions of streets such as providing space for mobility, social interactions, and cultural and recreational activities. The combination of these functions makes streets focal points of communities that do not only fulfill a functional role but also provide identity to cities. Streets are prominent parts of cities and are essential to sustainable transport plans. The main aim of the Street Networks and Sustainable Transportation collection is to focus on urban street networks and their effects on sustainable transportation. Accordingly, various street elements related to mobility, public transport, parking, design, and movement of people and goods at the street level can be included

AFRICA HABITAT REVIEW JOURNAL VOLUME 11 ISSUE 11 October 2017

N/

The quality of traditional streets in Indonesia

In the past few decades, the cities of Indonesia have experienced rapid development, with the transformation sometimes leading to improvements but often having a devastating impact on the urban environment. A worrying trend has been the reduction of the role of urban traditional streets in Indonesia as mixed-use and vibrant public places to become purely channels of movement, especially for car-based traffic. For this reason, this research focuses on assessing the quality of traditional streets in Indonesia and is being conducted before they disappear as a result of rapid development in urban areas. The primary aim of the research is to demonstrate the role of traditional streets in shaping the urban environment and urban public life. In this context, the research focuses on critically examining the distinctive characteristics of such streets through street quality indicators that have been developed in urban design discourses. A qualitative inquiry is chosen as the main research method with multiple case studies and a research strategy based on research questions, research knowledge, and expertise. The techniques to gain data were field observations (walk-by observations, pedestrian counts, and behavioural mapping) and in-depth interviews. The analysis procedure was a rationale-inductive method and relied on the data from the field work as the emerging information (data-led analysis). The research concludes that there are five major characteristics of traditional streets that play important roles to support urban public life; these are: the physical and visual quality of the street; traditional street as mixed-use urban space; as multi-cultural urban space; as a cultural path and public space of the city; and traditional street activities as intangible culture. The results of the study confirm the earlier findings that suggest that Asian street are vibrant places with mixed-use pavements that contribute significantly to the vibrancy of the city. This study adds to the knowledge of the potential of the traditional street in Indonesia as one of the primary urban spaces, as public space, as creative space, as cultural space, and as urban heritage that should be safeguarded and conserved for its outstanding value not only for its architectural diversity, but also for its intangible cultures. The research also recognises the important role of traditional streets in Indonesia to the contemporary city. The recognition of the integral entity of these streets including their economic, social, and the cultural life of the surrounding context have led to a better understanding in terms of research and can be part of the foundation to formulate better policy and design intervention for the future of Indonesian cities

Sustainable | Sustaining City Streets

Streets are an integral part of every city on Earth. They channel the people, vehicles, and materials that help make urban life what it is. They are conduits for the oft-taken-for-granted infrastructures that carry fresh water, energy, and information, and that remove excess stormwater and waste. The very air that we breathe—fresh or foul—flows through our street canyons. That streets are the arteries of the city is, indeed, an apt metaphor. But city streets also function as a front yard, linear ecosystem, market, performance stage, and civic forum, among other duties. In their various forms, streets are places of interaction and exchange, from the everyday to the extraordinary. As the editors affirm, the more we scrutinize, share, and activate sustainable approaches to streets, the greater the likelihood that our streets will help sustain life in cities and, by extension, the planet. While diverse in subject, the papers in this volume are unified in seeing the city street as the complex, impactful, and pliable urban phenomenon that it is. Topics range from greenstreets to transit networks to pedestrian safety and walkability. Anyone seeking interdisciplinary perspectives on what makes for good city streets and street networks should find this book of interest

The quality of traditional streets in Indonesia

In the past few decades, the cities of Indonesia have experienced rapid development, with the transformation sometimes leading to improvements but often having a devastating impact on the urban environment. A worrying trend has been the reduction of the role of urban traditional streets in Indonesia as mixed-use and vibrant public places to become purely channels of movement, especially for car-based traffic. For this reason, this research focuses on assessing the quality of traditional streets in Indonesia and is being conducted before they disappear as a result of rapid development in urban areas. The primary aim of the research is to demonstrate the role of traditional streets in shaping the urban environment and urban public life. In this context, the research focuses on critically examining the distinctive characteristics of such streets through street quality indicators that have been developed in urban design discourses. A qualitative inquiry is chosen as the main research method with multiple case studies and a research strategy based on research questions, research knowledge, and expertise. The techniques to gain data were field observations (walk-by observations, pedestrian counts, and behavioural mapping) and in-depth interviews. The analysis procedure was a rationale-inductive method and relied on the data from the field work as the emerging information (data-led analysis). The research concludes that there are five major characteristics of traditional streets that play important roles to support urban public life; these are: the physical and visual quality of the street; traditional street as mixed-use urban space; as multi-cultural urban space; as a cultural path and public space of the city; and traditional street activities as intangible culture. The results of the study confirm the earlier findings that suggest that Asian street are vibrant places with mixed-use pavements that contribute significantly to the vibrancy of the city. This study adds to the knowledge of the potential of the traditional street in Indonesia as one of the primary urban spaces, as public space, as creative space, as cultural space, and as urban heritage that should be safeguarded and conserved for its outstanding value not only for its architectural diversity, but also for its intangible cultures. The research also recognises the important role of traditional streets in Indonesia to the contemporary city. The recognition of the integral entity of these streets including their economic, social, and the cultural life of the surrounding context have led to a better understanding in terms of research and can be part of the foundation to formulate better policy and design intervention for the future of Indonesian cities

Drowned: Anishinabek Economies and Resistance to Hydroelectric Development -in the Winnipeg River Drainage Basin, 1873-1975

In 1893 the Keewatin Lumber and Power Company planned the first hydroelectric generating station on the north shore of Lake of the Woods (near present-day Kenora, Ontario). Approximately fifty years later, federal officials seeking employment for Canadian veterans turned to Northwestern Ontario and its underutilized water resources, envisioning a manufacturing hub on the Precambrian Shield. Between 1950 and 1958, the Hydroelectric Power Commission of Ontario remodeled the Winnipeg River drainage basin to produce power for federally-sanctioned peacetime industries, namely pulp and paper production. To redesign the Winnipeg River drainage basin, however, hydro officials needed to encroach on Anishinabek lands: both federally-recognized reserves and unrecognized, but heavily occupied, ancestral territories. This dissertation tells the story of how Anishinabek families used a diverse array of strategies adaptation, cooperation, and passive resistance to manage environmental change caused by Whitedog Falls Generating Station. Anishinabek families worked to stabilize their communities in an era of imposed environmental and economic change. Historians have long argued that hydroelectric development is necessarily at odds with Indigenous culture and subsistence economies. This dissertation provides a counter-narrative, arguing that cultural and economic damage, although linked to environmental damage, correlated more strongly with Anishinabek exclusion from resource negotiations. Moreover, this work complicates historical representations of a uniform Indigenous response to development. Given limited negotiations between the Hydro-Electric Power Commission and local First Nations, Anishinabek families did not respond to industrial incursions with one representative voice. The process of development itself, I argue, prevented a unified community response. As a result, Anishinabek communities fractured in response to hydroelectric development

Jane Jacobs is still here: Jane Jacobs 100 Her legacy and relevance in the 21st Century

On the occasion of Jane Jacobs’ 100 anniversary, the chair of Spatial Planning and Strategy of the Delft University of Technology, together with the OTB Research Institute for the Built Environment and the Rotterdam Erasmus University College organised a two-day conference on Jane Jacob’s legacy at TU Delft on 24-25 May 2016. This event was complemented one year later by a ‘Jane Jacobs Year’ closing event. We wished to celebrate the life and accomplishments of one of the most important urban thinkers of our time, someone who has influenced generations of designers and planners and others concerned with the built environment: the great Jane Jacobs.  Jacobs’ theories and ideas are seminal to many different academic fields: urban design, planning, architecture, sociology, human geography, environmental psychology, economic geography and many more. Her writings have been influential for more than five decades. This alone tells us of her importance for urban studies and for understanding the complex relationship between urban space and society. This is reflected, among other things, in the immense popularity of Jane’s ideas among young planners and designers. A simple Google search of the term “urban planner†yields the following results: A line-up of male planners is headed by a woman, the most relevant of them all (at least according to Google’s algorithms), Jane Jacobs! This is ironic since Jane Jacobs would hardly see herself as a planner. Maybe, like Roberta Gratz (who was a friend of Jacobs’), she was an ‘anti-planner’, someone with a keen eye for careful empirical observation, for whom cities ought to be understood from the careful exploration of how the built environment influences and is influenced by human life. Jacobs was an astute observer of the life of cities and the processes that produce both cities and citizenship. In their contributions, the authors of the texts included in this book demonstrate how Jacobs is still relevant as a theorist in the realms of politics, economics and design, and how she can also help us understand how urban form yields meaning. But they also criticise and review her ideas in light of the experiences accumulated in more than 50 years since her main works were published, and the perspectives of places that have little similarity to New York or Toronto. This is relevant because indeed Jane Jacobs’ ideas are being reviewed reinterpreted and reinvented, and occasionally refuted, in contexts as diverse as Cairo, São Paulo or Addis Ababa. And it’s high time this happens. The conference aimed to explore those new insights on Jacobs’ legacy and to take her ideas forward in the context of globalisation, internationalisation and accelerated urbanisation in places like China, India and Brazil. The intensity and scale of current urbanization are unprecedented and new challenges have emerged since she published her texts. How are the ideas of Jane Jacobs still relevant for the understanding of the interplay between urban space and society? Or do we need new theories? To what extent have Jacobs’ ideas inspired today’s urban leaders and thinkers? How are they tackling urban issues such as growing inequality, spatial fragmentation, street life, safety in the public space and environmental decline? We discussed Jacobs’ ideas critically and to take stock of how those ideas have been used, misused and hopefully updated. We invited abstract submissions for six different tracks, exploring essential aspects of Jacobs’ ideas: Track 1: Jane Jacobs, ethics, and the just city Track 2: Jane Jacobs and Street Spaces – Streets as public places Track 3: Jane Jacobs and the dynamics of neighbourhoods Track 4: Jane Jacobs and the Reshaping old urban fabrics in Chinese cities Track 5: Jane Jacobs and organised complexity Track 6: Jane Jacobs and safety in public space The conference was organised by Roberto Rocco (TU Delft Urbanism), Brian Doucet (University of Waterloo, Canada, then Erasmus University College in Rotterdam) and Andre Ouwehand (TU Delft OTB)