Polly's Polyhedral Scheduling in the Presence of Reductions

The polyhedral model provides a powerful mathematical abstraction to enable effective optimization of loop nests with respect to a given optimization goal, e.g., exploiting parallelism. Unexploited reduction properties are a frequent reason for polyhedral optimizers to assume parallelism prohibiting dependences. To our knowledge, no polyhedral loop optimizer available in any production compiler provides support for reductions. In this paper, we show that leveraging the parallelism of reductions can lead to a significant performance increase. We give a precise, dependence based, definition of reductions and discuss ways to extend polyhedral optimization to exploit the associativity and commutativity of reduction computations. We have implemented a reduction-enabled scheduling approach in the Polly polyhedral optimizer and evaluate it on the standard Polybench 3.2 benchmark suite. We were able to detect and model all 52 arithmetic reductions and achieve speedups up to 2.21$\times$ on a quad core machine by exploiting the multidimensional reduction in the BiCG benchmark.Comment: Presented at the IMPACT15 worksho

In search of the hollow crown

The first volume in a series of comparative studies within the ESRC's Whitehall Programme focuses on core executives in five parliamentary democracies comparing the Westminster model as in Australia, Canada and Britain with the continental democracies of Germany and the Netherlands showing how political leadership is shackled by a vast array of constraints, from globalisation to internal fragmentation and rationalisation, making a heroic model of decisive political leadership hard to sustain

Privatising Network Industries

privatization, regulation, competition, telecoms, electricity, gas, water, rail

The end of the Czech miracle? Currency crisis reveals need for institutional reforms

After years of high growth, low unemployment and low inflation, the Czech economy has suffered a sudden setback. Speculative attacks on the currency have forced the Central Bank to abandon its fixed exchange rate. The government has now announced austerity measures to reduce the massive current account deficit. In the short run, these measures will lead to lower growth and higher unemployment. Moreover, the devaluation of the Czech Koruna will make it more difficult to further reduce inflation. The crisis is due in part to the previous boom in domestic absorption. The expansion of absorption has been fuelled by massive capital inflows which helped to maintain the fixed exchange rate. At the same time, productivity growth has been sluggish despite high investment-to-GDP ratios, and wages have increased substantially despite sluggish productivity growth. These developments have contributed to the overvaluation of the exchange rate. As a result, the competitiveness of the tradables sector has been weakened, and the current account deficit has widened dramatically. The policy measures now announced aim at reducing domestic demand by cutting fiscal expenditure, raising taxes, devaluing the currency, and containing wage growth in the public sector. However, the government has so far failed to address the microeconomic issues that are at the heart of these supply-side problems. These include inefficiencies in financial intermediation, ineffective bankruptcy procedures, and weaknesses in the corporate governance of enterprises resulting from mass privatization. Solutions to the problems in the banking and financial sector should comprise tax incentives for banks to provision for loan losses, decentralized debt restructuring, the streamlining of bankruptcy proceedings, upgrading of the court system's resources, and a greater political will to enforce the existing bankruptcy legislation. Opening up for foreign banks more decisively and in particular allowing foreign banks to participate in the privatization of the large commercial banks can help to improve the efficiency of the banking system and the corporate governance role of banks. In order to encourage funds to manage their portfolios for the benefit of investors, funds should be encouraged to register as open-end unit trusts rather than as joint stock companies. On the macroeconomic level, the government is moving in the right direction. As regards the medium term outlook, fundamentals of the Czech economy remain strong. However, decisive and timely action to improve the institutional framework is needed if the economy is to overcome the present crisis and to reach a new, sustainable growth path. --

Abstracts : policy research working paper series - numbers 2071-2132

This paper contains abstracts of Policy Research Working Paper series Numbers 2071-2132.Environmental Economics&Policies,Health Monitoring&Evaluation,Health Economics&Finance,Achieving Shared Growth,Inequality

The disintegration of the ruble zone: Driving forces and proposals for policy change

This paper examines the irreversible process of the ruble zone disintegration. Theoretical fundamentals of a common currency area, with modifications incorporating a mechanism of transition from central planning, are discussed. The key reason for the ruble zone break-up is the discontinuation of indirect transfers that were provided mainly by Russia via underpricing energy exports to other republics. Being cut-off from such transfers and unable to finance rising trade deficits with Russia, the independent stales wish to disconnect their economies from the ruble /.one. Among other economic arguments for leaving the ruble zone presented by the former Soviet republics are: a desire to insulate their economies from the ruble zone inflation, and a willingness to collect seigniorage revenues from printing their own currencies. The paper critically evaluates these and several other arguments. The abrupt break-up of the ruble zone causes interruptions in supplies of essential materials and consumer goods, and an income downfall among the republics. The foundation for a new inter-state payments mechanism is proposed in order to cushion these negative effects. A system of independently traded currencies with flexible exchange rates is viewed as a reasonable, yet distant solution.

Private ownership and corporate performance : some lessons from transition economies

Using a large sample of data on mid-sized firms in the Czech Republic, Hungary, and Poland, the authors compare the performance of privatized and state firms in the environment of the postcommunist transition. They find strong evidence that private ownership--except for worker ownership-- dramatically improves corporate performance. They find no evidence of the"privatization shock"that was supposed to afflict the behavior of firms undergoing rapid changes in ownership. Instead, they observe a severe shock from marketization, affecting both state and privatized firms--but a shock for which private ownership provides a powerful antidote. Among their other findings are : a) Private ownership is most effective in improving a firm's ability to generate revenues, an area in which entrepreneurship seems to be required. Ownership also affects a firm's ability to remove the rather obvious cost inefficiencies inherited from the past, but this effect is less pronounced, as both state and privatized firms engage in significant cost restructuring. b) Privatized firms generate significantly more employment gains than state firms. It is their superior ability to generate revenues, rather than competence at cost-cutting, that allows them to sustain or expand employment. This is why privatization is the dominant strategy for expanding employment in transition. c) Outsider-owned firms perform better than insider-owned firms on most performance measures, but there is enough difference between employee- and manager-owned firms to suggest that putting all insiders under a common umbrella is unjustified. Although the effects of managerial ownership are ambiguous, putting employees in control appears to offer no advantages over state ownership on any measure and creates a distinct disadvantage in terms of employment performance. d) Among outsider owners, privatization funds seem to do as well at revitalizing the privatized companies as do other outsider owners; in particular, the authors find no evidence that funds are less effective than'strategic'investors. And foreign investors provide perhaps less of an edge than might have been expected; their impact appears no stronger than that of major domestic outsiders.Small and Medium Size Enterprises,Small Scale Enterprise,Microfinance,Banks&Banking Reform,International Terrorism&Counterterrorism,Microfinance,Private Participation in Infrastructure,Small Scale Enterprise,Banks&Banking Reform,Financial Crisis Management&Restructuring

Exploiting commutativity to reduce the cost of updates to shared data in cache-coherent systems

We present Coup, a technique to lower the cost of updates to shared data in cache-coherent systems. Coup exploits the insight that many update operations, such as additions and bitwise logical operations, are commutative: they produce the same final result regardless of the order they are performed in. Coup allows multiple private caches to simultaneously hold update-only permission to the same cache line. Caches with update-only permission can locally buffer and coalesce updates to the line, but cannot satisfy read requests. Upon a read request, Coup reduces the partial updates buffered in private caches to produce the final value. Coup integrates seamlessly into existing coherence protocols, requires inexpensive hardware, and does not affect the memory consistency model. We apply Coup to speed up single-word updates to shared data. On a simulated 128-core, 8-socket system, Coup accelerates state-of-the-art implementations of update-heavy algorithms by up to 2.4×.Center for Future Architectures ResearchNational Science Foundation (U.S.) (CAREER-1452994)Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science (Grier Presidential Fellowship)Microelectronics Advanced Research CorporationUnited States. Defense Advanced Research Projects Agenc

Reforming and privatizing Hungary's road haulage

The Volan units (previously unitary but now formally dismembered) provide public transport services for both passengers and freight, and make up the largest enterprise in Hungary's road transport industry. Immediately after separation in 1989, the Volan group of units employed 67,000 persons and operated 12,672 trucks and 8,010 buses. In 1989 Volan carried 34 percent of Hungary's professional road haulage tonne-kilometers. This report focuses on options for restructuring the Volan group. It therefore also considers the content and implementation of Hungary's overall road transport policy as well as related questions of finance and taxation, all of which define the conditions under which the Volan successor enterprises, however transformed, will have to prove themselves.Roads&Highways,Banks&Banking Reform,Municipal Financial Management,Transport and Trade Logistics,Common Carriers Industry

Debt management in Brazil : evaluation of the Real Plan and challenges ahead

Brazil's domestic debt has posed two challenges to policymakers: it has grown very fast and, despite progress, remains extremely short in maturity. The authors analyze Brazil's experience with domestic public debt management, searching for policy prescriptions for the next few years. After briefly reviewing the recent history of the country's domestic debt, they decompose the large rise in federal bonded debt in 1995-98, searching for its macroeconomic causes. The main explanations: extremely high interest payments (caused by Brazil's weak fiscal stance and quasi-fixed exchange rate regime) and the accumulation of assets (especially obligations of Brazil's states). Simulations of the net debt path for the near future underscore the importance of a tighter fiscal stance to prevent the debt-to-GDP ratio from growing further. The authors'main policy advice is to foster and rely more on inflation-linked bonds--the least harmful way to lengthen debt maturity.Economic Theory&Research,Banks&Banking Reform,Public Sector Economics&Finance,Payment Systems&Infrastructure,Strategic Debt Management,Economic Theory&Research,Banks&Banking Reform,Strategic Debt Management,Public Sector Economics&Finance,Municipal Financial Management