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Dive into the research topics where Johannes Singler is active.

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Featured researches published by Johannes Singler.


WEA'07 Proceedings of the 6th international conference on Experimental algorithms | 2007

Cache-, hash- and space-efficient bloom filters

Felix Putze; Peter Sanders; Johannes Singler

A Bloom filter is a very compact data structure that supports approximate membership queries on a set, allowing false positives. We propose several new variants of Bloom filters and replacements with similar functionality. All of them have a better cache-efficiency and need less hash bits than regular Bloom filters. Some use SIMD functionality, while the others provide an even better space efficiency. As a consequence, we get a more flexible trade-off between false positive rate, space-efficiency, cache-efficiency, hash-efficiency, and computational effort. We analyze the efficiency of Bloom filters and the proposed replacements in detail, in terms of the false positive rate, the number of expected cache-misses, and the number of required hash bits. We also describe and experimentally evaluate the performance of highly-tuned implementations. For many settings, our alternatives perform better than the methods proposed so far.


ACM Journal of Experimental Algorithms | 2009

Cache-, hash-, and space-efficient bloom filters

Felix Putze; Peter Sanders; Johannes Singler

A Bloom filter is a very compact data structure that supports approximate membership queries on a set, allowing false positives. We propose several new variants of Bloom filters and replacements with similar functionality. All of them have a better cache-efficiency and need less hash bits than regular Bloom filters. Some use SIMD functionality, while the others provide an even better space efficiency. As a consequence, we get a more flexible trade-off between false-positive rate, space-efficiency, cache-efficiency, hash-efficiency, and computational effort. We analyze the efficiency of Bloom filters and the proposed replacements in detail, in terms of the false-positive rate, the number of expected cache-misses, and the number of required hash bits. We also describe and experimentally evaluate the performance of highly tuned implementations. For many settings, our alternatives perform better than the methods proposed so far.


international conference on data engineering | 2010

Scalable distributed-memory external sorting

Mirko Rahn; Peter Sanders; Johannes Singler

We engineer algorithms for sorting huge data sets on massively parallel machines. The algorithms are based on the multiway merging paradigm. We first outline an algorithm whose I/O requirement is close to a lower bound. Thus, in contrast to naive implementations of multiway merging and all other approaches known to us, the algorithm works with just two passes over the data even for the largest conceivable inputs. A second algorithm reduces communication overhead and uses more conventional specifications of the result at the cost of slightly increased I/O requirements. An implementation wins the well known sorting benchmark in several categories and by a large margin over its competitors.


symposium on computational geometry | 2009

Parallel geometric algorithms for multi-core computers

Vicente H.F. Batista; David L. Millman; Sylvain Pion; Johannes Singler

Computers with multiple processor cores using shared memory are now ubiquitous. In this paper, we present several parallel geometric algorithms that specifically target this environment, with the goal of exploiting the additional computing power. The d-dimensional algorithms we describe are (a) spatial sorting of points, as is typically used for preprocessing before using incremental algorithms, (b) kd-tree construction, (c) axis-aligned box intersection computation, and finally (d) bulk insertion of points in Delaunay triangulations for mesh generation algorithms or simply computing Delaunay triangulations. We show experimental results for these algorithms in 3D, using our implementations based on the Computational Geometry Algorithms Library (CGAL, http://www.cgal.org/). This work is a step towards what we hope will become a parallel mode for CGAL, where algorithms automatically use the available parallel resources without requiring significant user intervention.


european conference on parallel processing | 2007

Parallelization of bulk operations for STL dictionaries

Leonor Frias; Johannes Singler

STL dictionaries like map and set are commonly used in C++ programs. We consider parallelizing two of their bulk operations, namely the construction from many elements, and the insertion of many elements at a time. Practical algorithms are proposed for these tasks. The implementation is completely generic and engineered to provide best performance for the variety of possible input characteristics. It features transparent integration into the STL. This can make programs profit in an easy way from multi-core processing power. The performance measurements show the practical usefulness on real-world multi-core machines with up to eight cores.


acm sigplan symposium on principles and practice of parallel programming | 2007

MCSTL: the multi-core standard template library

Felix Putze; Peter Sanders; Johannes Singler

Future gain in computing performance will not stem from increased clock rates, but from even more cores in a processor. Since automatic parallelization is still limited to easily parallelizable sections of the code, most applications will soon have to support parallelism explicitly. The Multi-Core Standard Template Library (MCSTL) simplifies parallelization by providing efficient parallel implementations of the algorithms in the C++ Standard Template Library. Thus, simple recompilation will provide partial parallelization of applications that make consistent use of the STL. We present performance measurements on several architectures. For example, our sorter achieves a speedup of 21 on an 8-core 32-thread SUN T1.


complex, intelligent and software intensive systems | 2008

Single-Pass List Partitioning

Leonor Frias; Johannes Singler; Peter Sanders

Parallel algorithms divide computation among several threads. In many cases, the input must also be divided. Consider an input consisting of a linear sequence of elements whose length is unknown a priori. We can evenly divide it naively by either traversing it twice (first determine length, then divide) or by using linear additional memory to hold an array of pointers to the elements. Instead, we propose an algorithm that divides a linear sequence into p parts of similar length traversing the sequence only once, and using sub-linear additional space. The experiments show that our list partitioning algorithm is effective and fast in practice.


Journal of Scheduling | 2013

Real-time integrated prefetching and caching

Peter Sanders; Johannes Singler; Rob van Stee

The high latencies for access to background memory like hard disks or flash memory can be reduced by caching or hidden by prefetching. We consider the problem of scheduling the resulting I/Os when the available fast cache memory is limited and when we have real-time constraints where for each requested data block we are given a time interval during which this block needs to be in main memory. We give a near linear time algorithm for this problem which produces a feasible schedule whenever one exists. Another algorithm additionally minimizes I/Os and still runs in polynomial-time. For the online variant of the problem, we give a competitive algorithm that uses lookahead and augmented disk speed. We show a tight relationship between the amount of lookahead and the speed required to get a competitive algorithm.


algorithm engineering and experimentation | 2010

Simple and fast nearest neighbor search

Marcel Birn; Manuel Holtgrewe; Peter Sanders; Johannes Singler


algorithm engineering and experimentation | 2009

The Filter-Kruskal minimum spanning tree algorithm

Vitaly Osipov; Peter Sanders; Johannes Singler

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Peter Sanders

Karlsruhe Institute of Technology

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Felix Putze

Karlsruhe Institute of Technology

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Andreas Beckmann

Goethe University Frankfurt

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Ulrich Meyer

Goethe University Frankfurt

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Leonor Frias

Polytechnic University of Catalonia

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Manuel Holtgrewe

Karlsruhe Institute of Technology

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Marcel Birn

Karlsruhe Institute of Technology

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Mirko Rahn

Karlsruhe Institute of Technology

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Vitaly Osipov

Karlsruhe Institute of Technology

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