Speculative Staging for Interpreter Optimization

Interpreters have a bad reputation for having lower performance than just-in-time compilers. We present a new way of building high performance interpreters that is particularly effective for executing dynamically typed programming languages. The key idea is to combine speculative staging of optimized interpreter instructions with a novel technique of incrementally and iteratively concerting them at run-time. This paper introduces the concepts behind deriving optimized instructions from existing interpreter instructions---incrementally peeling off layers of complexity. When compiling the interpreter, these optimized derivatives will be compiled along with the original interpreter instructions. Therefore, our technique is portable by construction since it leverages the existing compiler's backend. At run-time we use instruction substitution from the interpreter's original and expensive instructions to optimized instruction derivatives to speed up execution. Our technique unites high performance with the simplicity and portability of interpreters---we report that our optimization makes the CPython interpreter up to more than four times faster, where our interpreter closes the gap between and sometimes even outperforms PyPy's just-in-time compiler.Comment: 16 pages, 4 figures, 3 tables. Uses CPython 3.2.3 and PyPy 1.

Reclaiming Waste, Remaking Communities: Persistence and Change in Delhi's Informal Garbage Economy

Reclaiming Waste, Remaking Communities: Persistence and Change in Delhi's Informal Garbage Economy examines the unanticipated impact of expanded municipal garbage collection services in Delhi, India in the mid-2000s through public-private partnerships (PPP) that included collection trucks and incinerators. Drawing on twenty months of ethnographic research, I ask how it is that informal collectors, who rely on pedal-powered tricycle carts and their hands to extract recyclables, have survived the expansion of these formal services that threatened their livelihoods and the city's only system for recycling. Despite being heavily supported by the government, these PPP services were effectively stalled and transformed by the resilience of the collector-recyclers’ unofficial enterprise, ensuring the continuation of a recycling network. The manuscript addresses the following questions: What do economic relations look like in this context, and what kinds of moral economies configure them? How are social relations and status distinctions reproduced and transformed through transactions of garbage and money? And how does the legacy, experience, and threat of stigmatization—embodied in the idea and object of garbage and ranging in scale from individual practice to global reputation maintenance—shape transactional possibilities? Revealing how forms of economic life across multiple scales depend on caste/community relations, the navigation of caste and (post)colonial stigma, and the reproduction of status through transactions, the dissertation brings together literatures from economic sociology and anthropology, political ecology, and theories of caste/race in order to explain persistent forms of unofficial economic organization.PHDSociologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162989/1/danakorn_1.pd

Underutilised Resources in Urban Environments

This book is the result of a Special Issue of the journal Resources. The Special Issue was initiated to identify promising solutions and specific challenges in the context of underused resources in urban environments. Authors focus on two main areas: the establishment of circular economy schemes based on valorizing wastes that occur in urban areas and the exploitation of renewable energies. The circular economy and renewable resources hold key potential for increasing the sustainability of cities, and the presented studies enhance our understanding of how to unlock this potential. Effective regulatory frameworks and policymaking processes that balance the power between stakeholders are required to successfully manage energy transition and the transition to more circular economies. The positive role of community engagement merits high attention. To recover valuable resources from household waste, a focus on technology and infrastructure is required but is insufficient; motivational factors and knowledge of citizens are the most essential elements. The need to more reliably quantify and better characterize recyclable material streams also evidently remains, especially where population numbers are further growing. This book provides a rich source to explore promising solutions, challenges, and research needed for the sound management of resources in urban settings

Applications of systems thinking in integrated solid waste management planning for African cities: the case of Nairobi, Kenya

The majority of solid waste generated by urban living cannot be assimilated in the city environment,and initial improvements in urban cleanliness and health were only realized when organized wastecollection and disposal outside of city limits was introduced in Europe in the late 19th century.Sanitary landfills were later invented to reduce the environmental effects of large unsecureddumpsites, it is now however increasingly being shown that this too as a waste management strategyoffers a worse environmental footprint than material and energy recovery and recycling (Cherubini et01., 2009). Modern approaches to solid waste management, collectively referred to as Integrated Solid Waste Management (ISWM), therefore increasingly incorporate strategies to reduce wastegeneration and to encourage re-use and recycling of materials, and recovery of energy; with landfilling as a last option for residual waste. This represents a shift in waste management paradigmsfrom a focus on collection for disposal, to an increasing integrated interest in the entire waste chainfrom waste generation to material and energy recovery and recycling, and to safe residual treatmentand disposal. The increasing acceptance of Mebratu's (1998) cosmic interdependence model as amore realistic conceptualisation of our world and how its natural, social, and economic spheresinteract however implies that sustainable waste management design needs to take a further leapinto a systems discourse, and cannot be considered in isolation of a rigorous understanding of thesystemic interactions of the social and economic circumstances unique to particular areas. This callsfor a greater understanding of how ISWM principles fit within the social and economic contexts ofgiven areas; an analytical gap that can be filled through the use of systems thinking and systemsbasedtools to multi-dimensionally investigate, and articulate the structures and relationships thatoften underlie complex situations. While systems thinking has found wide application in thesustainability sciences as a prerequisite to building truly sustainable systems (for example Capra,2002 and Hjorth & Bagheri, 2006), it has as yet found little application in waste management analysisand designs, which have evolved from simple problem-oriented to ""integrated"" engineeringmethods. In response to dire solid waste conditions in Nairobi, the government of Kenya agreed in 2009 tocollaborate with UNEP to develop an ISWM Strategy for Nairobi. The project was initiated in March2009, and a National Task Team was established to oversee the development of the plan along with ateam from the University of Cape Town, of which the author was part. The core elements of theresulting Nairobi City ISWM Strategy (CCN & UNEP, 2010) were finalised in April 2010 and included,alongside the formal use of the UNEP ISWM planning methodology, some application of systemsanalysis. These systems analyses could however only be partially developed due to project deliverytime constraints, and this dissertation extends these analyses to completion and explores theirimplications for ISWM in Nairobi.Systems based tools from the research area of system dynamics were applied to systematicallystructure the waste problem and situation in Nairobi, and to develop conceptual causal loop modelsarticulating the solid waste system in Nairobi as a whole. This enabled the highlighting of inherentwaste system strengths and weaknesses in Nairobi, system drivers, leverage points, behaviouralarchetypes, and resulting implications for ISWM planning in Nairobi. The insights generated wereused to inform an examination of whether the intervention strategies finally developed in theNairobi ISWM Strategy Plan (CCN & UNEP, 2010) were adequate at a fundamental level andsufficiently relevant. It was also determined that the bulk of Nairobi's solid waste is organic, and thatthe material recycling and reuse capacity in the city is a key system driver in its waste management towards ISWM, of which organic waste valorization comprises a significant part. It was therefore ofinterest to determine the current capacity, and potential for expansion of organic waste valorizationin the city towards amplifying material recycling as a system driver towards ISWM.The application of a systems based analysis of Nairobi's waste management identified the presenceof ten system drivers of varying nature and flexibility, through which to influence the achievement ofISWM objectives in the city. Potential system leverage points in Nairobi's waste sector were alsoidentified and allowed the development of additional systemic interventions through which largewaste sector changes towards ISWM may be achieved with relatively small inputs. The solid wastemanagement scene in Nairobi was also found to involve a combination of two systems archetypes asdefined by Braun (2002): a 'Success to the successful' trend of private waste collection relative to theCity Council, embedded within a larger 'Tragedy of the Commons' trend - the commons being thecity's economic, human, and natural capital; and implicitly its potential revenue base for collectionservice providers, whose tragic diminishing for all will be the inevitable result if the current operationand disposal practices of both the private collectors and the City Council continue. The interventionsproposed in the Nairobi ISWM Strategy (CCN & UNEP, 2010) were found to have targeted many ofthe fundamental causes leading to the current solid waste situation in Nairobi, due in part to thepartial use of systems analysis in their development by the author; additional insights were howevergenerated from the completed systems analysis discussed in this dissertation. These highlight a needfor the development of policy consistent with eight extra systemic interventions, six of which may beconsidered critical to the success of ISWM efforts in Nairobi.The latter focus on the potential of organic waste valorization to amplify Nairobi's material recyclingcapacity as a waste system driver towards ISWM revealed that there is a leakage of 14% to 23% of allwaste in the city due to organic waste degradation at open dumps or collection points. There is acurrent interest in the use of such organic wastes as animal feed in Nairobi City, and this userepresents a promising but seemingly under tapped organic waste valorisation potential that is likelyto gain in importance in future. Bulk compost production from organic waste is uneconomical underthe present market conditions in the city, and does not currently offer a rational option for the bulkvalorisation of organic wastes in Nairobi. The anaerobic digestion of organic waste for energyhowever shows potential to achieve radically improved organic waste valorisation levels in the city,and from techno-economic modelling undertaken of potential medium scale biogas-to-energy plantinvestments, seems feasible at the current biogas energy feed-in tariffs of 6 KShs/kWh (17-19 US Cents/kWh) and an organic waste tipping fee of KShs. l/kg organic wastetreated, is recommended to achieve more attractive investment payback periods of under five yearsfor especially private investors, and generally agrees with feed-in tari

FP2: Fully in-Place Functional Programming

As functional programmers we always face a dilemma: should we write purely functional code, or sacrifice purity for efficiency and resort to in-place updates? This paper identifies precisely when we can have the best of both worlds: a wide class of purely functional programs can be executed safely using in-place updates without requiring allocation, provided their arguments are not shared elsewhere. We describe a linear fully in-place (FIP) calculus where we prove that we can always execute such functions in a way that requires no (de)allocation and uses constant stack space. Of course, such a calculus is only relevant if we can express interesting algorithms; we provide numerous examples of in-place functions on datastructures such as splay trees or finger trees, together with in-place versions of merge sort and quick sort. We also show how we can generically derive a map function over any polynomial data type that is fully in-place. Finally, we have implemented the rules of the FIP calculus in the Koka language. Using the Perceus reference counting garbage collection, this implementation dynamically executes FIP functions in-place whenever possibl

Constructive tool design for formal languages : from semantics to executing models

Embedded, distributed, real-time, electronic systems are becoming more and more dominant in our lives. Hidden in cars, televisions, mp3-players, mobile phones and other appliances, these hardware/software systems influence our daily activities. Their design can be a huge effort and has to be carried out by engineers in a limited amount of time. Computer-aided modelling and design automation shorten the design cycle of these systems enabling companies to deliver their products sooner than their competitors. The design process is divided into different levels of abstraction, starting with a vague product idea (abstract) and ending up with a concrete description ready for implementation. Recently, research has started to focus on the system level, being a promising new area at which the product design could start. This dissertation develops a constructive approach to building tools for system-level design/description/modelling/specification languages, and shows the applicability of this method to the system-level language POOSL (Parallel Object-Oriented Specification Language). The formal semantics of this language is redefined and partly redeveloped, adding probabilistic features, real-time, inheritance, concurrency within processes, dynamic ports and atomic (indivisible) expressions, making the language suitable for performance analysis/modelling. The semantics is two-layered, using a probabilistic denotational semantics for stating the meaning of POOSL’s data layer, and using a probabilistic structural operational semantics for the process layer and architecture layer. The constructive approach has yielded the system-level simulation tool rotalumis, capable of executing large industrial designs, which has been demonstrated by two successful case studies—an ATM-packet switch (in conjunction with IBM Research at Z¨urich) and a packet routing switch for the Internet (in association with Alcatel/Bell at Antwerp). The more generally applicable optimisations of the execution engine (rotalumis) and the decisions taken in its design are discussed in full detail. Prototyping, where the system-level model functions as a part of the prototype implementation of the designed product, is supported by rotalumis-rt, a real-time variant of the execution engine. The viability of prototyping is shown by a case study of a learning infrared remote control, partially realised in hardware and completed with a system-level model. Keywords formal languages / formal specification / modelling languages / systemlevel design / embedded systems / real-time systems / performance analysis / discrete event simulation / probabilistic process algebra / design automation / prototyping / simulation tool

Resource-aware Programming in a High-level Language - Improved performance with manageable effort on clustered MPSoCs

Bis 2001 bedeutete Moores und Dennards Gesetz eine Verdoppelung der Ausführungszeit alle 18 Monate durch verbesserte CPUs. Heute ist Nebenläufigkeit das dominante Mittel zur Beschleunigung von Supercomputern bis zu mobilen Geräten. Allerdings behindern neuere Phänomene wie "Dark Silicon" zunehmend eine weitere Beschleunigung durch Hardware. Um weitere Beschleunigung zu erreichen muss sich auch die Soft­ware mehr ihrer Hardware Resourcen gewahr werden. Verbunden mit diesem Phänomen ist eine immer heterogenere Hardware. Supercomputer integrieren Beschleuniger wie GPUs. Mobile SoCs (bspw. Smartphones) integrieren immer mehr Fähigkeiten. Spezialhardware auszunutzen ist eine bekannte Methode, um den Energieverbrauch zu senken, was ein weiterer wichtiger Aspekt ist, welcher mit der reinen Geschwindigkeit abgewogen werde muss. Zum Beispiel werden Supercomputer auch nach "Performance pro Watt" bewertet. Zur Zeit sind systemnahe low-level Programmierer es gewohnt über Hardware nachzudenken, während der gemeine high-level Programmierer es vorzieht von der Plattform möglichst zu abstrahieren (bspw. Cloud). "High-level" bedeutet nicht, dass Hardware irrelevant ist, sondern dass sie abstrahiert werden kann. Falls Sie eine Java-Anwendung für Android entwickeln, kann der Akku ein wichtiger Aspekt sein. Irgendwann müssen aber auch Hochsprachen resourcengewahr werden, um Geschwindigkeit oder Energieverbrauch zu verbessern. Innerhalb des Transregio "Invasive Computing" habe ich an diesen Problemen gearbeitet. In meiner Dissertation stelle ich ein Framework vor, mit dem man Hochsprachenanwendungen resourcengewahr machen kann, um so die Leistung zu verbessern. Das könnte beispielsweise erhöhte Effizienz oder schnellerer Ausführung für das System als Ganzes bringen. Ein Kerngedanke dabei ist, dass Anwendungen sich nicht selbst optimieren. Stattdessen geben sie alle Informationen an das Betriebssystem. Das Betriebssystem hat eine globale Sicht und trifft Entscheidungen über die Resourcen. Diesen Prozess nennen wir "Invasion". Die Aufgabe der Anwendung ist es, sich an diese Entscheidungen anzupassen, aber nicht selbst welche zu fällen. Die Herausforderung besteht darin eine Sprache zu definieren, mit der Anwendungen Resourcenbedingungen und Leistungsinformationen kommunizieren. So eine Sprache muss ausdrucksstark genug für komplexe Informationen, erweiterbar für neue Resourcentypen, und angenehm für den Programmierer sein. Die zentralen Beiträge dieser Dissertation sind: Ein theoretisches Modell der Resourcen-Verwaltung, um die Essenz des resourcengewahren Frameworks zu beschreiben, die Korrektheit der Entscheidungen des Betriebssystems bezüglich der Bedingungen einer Anwendung zu begründen und zum Beweis meiner Thesen von Effizienz und Beschleunigung in der Theorie. Ein Framework und eine Übersetzungspfad resourcengewahrer Programmierung für die Hochsprache X10. Zur Bewertung des Ansatzes haben wir Anwendungen aus dem High Performance Computing implementiert. Eine Beschleunigung von 5x konnte gemessen werden. Ein Speicherkonsistenzmodell für die X10 Programmiersprache, da dies ein notwendiger Schritt zu einer formalen Semantik ist, die das theoretische Modell und die konkrete Implementierung verknüpft. Zusammengefasst zeige ich, dass resourcengewahre Programmierung in Hoch\-sprachen auf zukünftigen Architekturen mit vielen Kernen mit vertretbarem Aufwand machbar ist und die Leistung verbessert

Tools for sustainability assessment and management : food chains and household waste case studies

Sustainability is the ability of a system to overcome shocks and stresses in seeking a balance upon the interactions of ecological, economic and social systems. Many countries have set national strategies for pursuing higher sustainability, including sustainability targets and indicators. Several attempts were undertaken to make the agricultural sector in general and the food sector in particular more sustainable. However, there is no harmonized standard defining what sustainable production should involve. Moreover, there is no agreement on which set of indicators to include when measuring sustainability performance in order to create more sustainable food chains. The commonly used measure for sustainability is the ecological footprint. Literature proves that this measure has a lot of limitations and there should be better ones. The doctoral research is divided in three major parts, comprising sustainability assessment tools. Part 1 of the doctoral research focuses on the carbon footprint as a potential alternative for the ecological footprint. Part 2 thoroughly investigates the factors influencing waste generation, a huge sustainability problem. Part 3 examines the possibility and necessity to measure sustainability as 1 composite indicator by creating a tool covering the 3 main sustainability systems. Soy is one of the main feed compound ingredients and Brazil is one of the main producers and exporters of soymeal. Given Brazil’s position in the soy world market on the one hand and accompanying sustainability issues on the other hand, assessing the sustainability performance of this global value chain is of utmost importance