Tim Rühl

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Orca is a portable, object-based distributed shared memory (DSM) system. This article studies and evaluates the design choices made in the Orca system and compares Orca with other DSMs. The article gives a quantitative analysis of Orca's coherence protocol (based on write-updates with function shipping), the totally ordered group communication protocol, the(More)
The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most(More)
This paper studies the implementation of efficient mul-ticast protocols for Myrinet, a switched, wormhole-routed, Gigabit-per-second network technology. Since Myrinet does not support multicasting in hardware, multicast services must be implemented in software. We present a new, efficient, and reliable software multicast protocol that uses the network(More)
This paper surveys the design issues for user-level network interface protocols for modern high-speed networks such as Myrinet. It first explains the principles of such protocols through a simple, unreliable protocol. Next, six important design issues are discussed in more detail: data transfers, address translation, protection, control transfers,(More)
Clusters of workstations are often claimed to be a good platform for parallel processing, especially if a fast network is used to interconnect the workstations. Indeed, high performance can be obtained for low-level message passing primitives on modern networks like ATM and Myrinet. Most application programmers, however, want to use higher-level(More)
Panda is a virtual machine designed to support portable implementations of parallel programming systems. It provides communication primitives and thread support to higher-level layers (such as a runtime system). We have used Panda to implement four parallel programming systems: Orca, data parallel Orca, PVM, and SR. The paper describes our experiences in(More)
We systematically evaluate the performance of five implementations of a single, user-level communication interface. Each implementation makes different architectural assumptions about the reliability of the network hardware and the capabilities of the network interface. The implementations differ accordingly in their division of protocol tasks between host(More)
Data Mining places specific requirements on DBMS query performance that cannot be evaluated satisfactorily using existing OLAP benchmarks. The DD Benchmark-defined here-provides a practical case and yardstick to explore how well a DBMS is able to support Data Mining applications. It was derived from real-life data mining tasks performed by our Data(More)