@misc{ReinefeldSchintkeSchuett, author = {Reinefeld, Alexander and Schintke, Florian and Sch{\"u}tt, Thorsten}, title = {P2P Routing of Range Queries in Skewed Multidimensional Data Sets}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-9671}, number = {07-23}, abstract = {We present a middleware to store multidimensional data sets on Internet-scale distributed systems and to efficiently perform range queries on them. Our structured overlay network \emph{SONAR (Structured Overlay Network with Arbitrary Range queries)} puts keys which are adjacent in the key space on logically adjacent nodes in the overlay and is thereby able to process multidimensional range queries with a single logarithmic data lookup and local forwarding. The specified ranges may have arbitrary shapes like rectangles, circles, spheres or polygons. Empirical results demonstrate the routing performance of SONAR on several data sets, ranging from real-world data to artificially constructed worst case distributions. We study the quality of SONAR's routing information which is based on local knowledge only and measure the indegree of the overlay nodes to find potential hot spots in the routing process. We show that SONAR's routing table is self-adjusting, even under extreme situations, keeping always a maximum of \$\lceil \log N \rceil\$ routing entries.}, language = {en} } @misc{SchuettSchintkeReinefeld, author = {Sch{\"u}tt, Thorsten and Schintke, Florian and Reinefeld, Alexander}, title = {Chord\#: Structured Overlay Network for Non-Uniform Load-Distribution}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-8736}, number = {05-40}, abstract = {\newcommand{\chordsharp}{Chord\$^\\#\#\$} Data lookup is a fundamental problem in peer-to-peer systems: Given a key, find the node that stores the associated object. Chord and other P2P algorithms use distributed hash tables (DHTs) to distribute the keys and nodes evenly across a logical ring. Using an efficient routing strategy, DHTs provide a routing performance of \$O (\log N)\$ in networks of \$N\$ nodes. While the routing performance has been shown to be optimal, the uniform key distribution makes it impossible for DHTs to support range queries. For range queries, consecutive keys must be stored on lo gically neighboring nodes. In this paper, we present an enhancement of Chord that eliminates the hash function while keeping the same routing performance. The resulting algorithm, named \chordsharp{}, provides a richer function ality while maintaining the same complexity. In addition to Chord, \chordsharp{} adapts to load imbalance.}, language = {en} } @misc{DoebbelinSchuettReinefeld, author = {D{\"o}bbelin, Robert and Sch{\"u}tt, Thorsten and Reinefeld, Alexander}, title = {Building Large Compressed PDBs for the Sliding Tile Puzzle}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-18095}, abstract = {The performance of heuristic search algorithms depends crucially on the effectiveness of the heuristic. A pattern database (PDB) is a powerful heuristic in the form of a pre-computed lookup table. Larger PDBs provide better bounds and thus allow more cut-offs in the search process. Today, the largest PDB for the 24-puzzle is a 6-6-6-6 PDB with a size of 486 MB. We created 8-8-8, 9-8-7 and 9-9-6 PDBs that are three orders of magnitude larger (up to 1.4 TB) than the 6-6-6-6 PDB. We show how to compute such large PDBs and we present statistical and empirical data on their efficiency. The largest single PDB gives on average an 8-fold improvement over the 6-6-6-6 PDB. Combining several large PDBs gives on average an 12-fold improvement.}, language = {en} } @inproceedings{WendeNoackSchuettetal., author = {Wende, Florian and Noack, Matthias and Sch{\"u}tt, Thorsten and Sachs, Stephen and Steinke, Thomas}, title = {Application Performance on a Cray XC30 Evaluation System with Xeon Phi Coprocessors at HLRN-III}, series = {Cray User Group}, booktitle = {Cray User Group}, language = {en} } @inproceedings{SalemSchuettSchintkeetal., author = {Salem, Farouk and Sch{\"u}tt, Thorsten and Schintke, Florian and Reinefeld, Alexander}, title = {Scheduling Data Streams for Low Latency and High Throughput on a Cray XC40 Using Libfabric}, series = {CUG Conference Proceedings}, booktitle = {CUG Conference Proceedings}, abstract = {Achieving efficient many-to-many communication on a given network topology is a challenging task when many data streams from different sources have to be scattered concurrently to many destinations with low variance in arrival times. In such scenarios, it is critical to saturate but not to congest the bisectional bandwidth of the network topology in order to achieve a good aggregate throughput. When there are many concurrent point-to-point connections, the communication pattern needs to be dynamically scheduled in a fine-grained manner to avoid network congestion (links, switches), overload in the node's incoming links, and receive buffer overflow. Motivated by the use case of the Compressed Baryonic Matter experiment (CBM), we study the performance and variance of such communication patterns on a Cray XC40 with different routing schemes and scheduling approaches. We present a distributed Data Flow Scheduler (DFS) that reduces the variance of arrival times from all sources at least 30 times and increases the achieved aggregate bandwidth by up to 50\%.}, language = {en} } @article{SalemSchintkeSchuettetal., author = {Salem, Farouk and Schintke, Florian and Sch{\"u}tt, Thorsten and Reinefeld, Alexander}, title = {Scheduling data streams for low latency and high throughput on a Cray XC40 using Libfabric}, series = {Concurrency and Computation Practice and Experience}, volume = {32}, journal = {Concurrency and Computation Practice and Experience}, number = {20}, doi = {10.1002/cpe.5563}, pages = {1 -- 14}, language = {en} } @article{SalemSchintkeSchuettetal., author = {Salem, Farouk and Schintke, Florian and Sch{\"u}tt, Thorsten and Reinefeld, Alexander}, title = {Improving the throughput of a scalable FLESnet using the Data-Flow Scheduler}, series = {CBM Progress Report 2018}, journal = {CBM Progress Report 2018}, isbn = {978-3-9815227-6-1}, doi = {10.15120/GSI-2019-01018}, pages = {149 -- 150}, language = {en} } @article{SalemSchintkeSchuettetal., author = {Salem, Farouk and Schintke, Florian and Sch{\"u}tt, Thorsten and Reinefeld, Alexander}, title = {Supporting various interconnects in FLESnet using Libfabric}, series = {CBM Progress Report 2016}, journal = {CBM Progress Report 2016}, isbn = {978-3-9815227-4-7}, pages = {159 -- 160}, language = {en} } @article{SalemSchintkeSchuettetal., author = {Salem, Farouk and Schintke, Florian and Sch{\"u}tt, Thorsten and Reinefeld, Alexander}, title = {Data-flow scheduling for a scalable FLESnet}, series = {CBM Progress Report 2017}, journal = {CBM Progress Report 2017}, isbn = {978-3-9815227-5-4}, doi = {10.15120/GSI-2018-00485}, pages = {130 -- 131}, language = {en} } @inproceedings{GholamiSchintkeSchuett, author = {Gholami, Masoud and Schintke, Florian and Sch{\"u}tt, Thorsten}, title = {Checkpoint Scheduling for Shared Usage of Burst-Buffers in Supercomputers}, series = {Proceedings of the 47th International Conference on Parallel Processing Companion; SRMPDS 2018: The 14th International Workshop on Scheduling and Resource Management for Parallel and Distributed Systems}, booktitle = {Proceedings of the 47th International Conference on Parallel Processing Companion; SRMPDS 2018: The 14th International Workshop on Scheduling and Resource Management for Parallel and Distributed Systems}, doi = {10.1145/3229710.3229755}, pages = {44:1 -- 44:10}, abstract = {User-defined and system-level checkpointing have contrary properties. While user-defined checkpoints are smaller and simpler to recover, system-level checkpointing better knows the global system's state and parameters like the expected mean time to failure (MTTF) per node. Both approaches lead to non-optimal checkpoint time, intervals, sizes, or I/O bandwidth when concurrent checkpoints conflict and compete for it. We combine user-defined and system-level checkpointing to exploit the benefits and avoid the drawbacks of each other. Thus, applications frequently offer to create checkpoints. The system accepts such offers according to the current status and implied costs to recalculate from the last checkpoint or denies them, i.e., immediately lets continue the application without checkpoint creation. To support this approach, we develop economic models for multi-application checkpointing on shared I/O resources that are dedicated for checkpointing (e.g. burst-buffers) by defining an appropriate goal function and solving a global optimization problem. Using our models, the checkpoints of applications on a supercomputer are scheduled to effectively use the available I/O bandwidth and minimize the failure overhead (checkpoint creations plus recalculations). Our simulations show an overall reduction in failure overhead of all nodes of up to 30\% for a typical supercomputer workload (HLRN). We can also derive the most cost effective burst-buffer bandwidth for a given node's MTTF and application workload.}, language = {en} } @inproceedings{WeinholdLackorzynskiBierbaumetal., author = {Weinhold, Carsten and Lackorzynski, Adam and Bierbaum, Jan and K{\"u}ttler, Martin and Planeta, Maksym and Weisbach, Hannes and Hille, Matthias and H{\"a}rtig, Hermann and Margolin, Alexander and Sharf, Dror and Levy, Ely and Gak, Pavel and Barak, Amnon and Gholami, Masoud and Schintke, Florian and Sch{\"u}tt, Thorsten and Reinefeld, Alexander and Lieber, Matthias and Nagel, Wolfgang}, title = {FFMK: A Fast and Fault-Tolerant Microkernel-Based System for Exascale Computing}, series = {Software for Exascale Computing - SPPEXA 2016-2019}, booktitle = {Software for Exascale Computing - SPPEXA 2016-2019}, publisher = {Springer}, doi = {10.1007/978-3-030-47956-5_16}, pages = {483 -- 516}, language = {en} } @misc{GholamiSchintkeSchuettetal., author = {Gholami, Masoud and Schintke, Florian and Sch{\"u}tt, Thorsten and Reinefeld, Alexander}, title = {Modeling Checkpoint Schedules for Concurrent HPC Applications}, series = {CoSaS 2018 International Symposium on Computational Science at Scale}, journal = {CoSaS 2018 International Symposium on Computational Science at Scale}, language = {en} }