2 Search Results for "Lozi, Jean-Pierre"

Document
DOI: 10.4230/LIPIcs.OPODIS.2020.17
CSR++: A Fast, Scalable, Update-Friendly Graph Data Structure

Authors: Soukaina Firmli, Vasileios Trigonakis, Jean-Pierre Lozi, Iraklis Psaroudakis, Alexander Weld, Dalila Chiadmi, Sungpack Hong, and Hassan Chafi

Published in: LIPIcs, Volume 184, 24th International Conference on Principles of Distributed Systems (OPODIS 2020)

Abstract
The graph model enables a broad range of analysis, thus graph processing is an invaluable tool in data analytics. At the heart of every graph-processing system lies a concurrent graph data structure storing the graph. Such a data structure needs to be highly efficient for both graph algorithms and queries. Due to the continuous evolution, the sparsity, and the scale-free nature of real-world graphs, graph-processing systems face the challenge of providing an appropriate graph data structure that enables both fast analytical workloads and low-memory graph mutations. Existing graph structures offer a hard trade-off between read-only performance, update friendliness, and memory consumption upon updates. In this paper, we introduce CSR++, a new graph data structure that removes these trade-offs and enables both fast read-only analytics and quick and memory-friendly mutations. CSR++ combines ideas from CSR, the fastest read-only data structure, and adjacency lists to achieve the best of both worlds. We compare CSR++ to CSR, adjacency lists from the Boost Graph Library, and LLAMA, a state-of-the-art update-friendly graph structure. In our evaluation, which is based on popular graph-processing algorithms executed over real-world graphs, we show that CSR++ remains close to CSR in read-only concurrent performance (within 10% on average), while significantly outperforming CSR (by an order of magnitude) and LLAMA (by almost 2×) with frequent updates.
Cite as

Soukaina Firmli, Vasileios Trigonakis, Jean-Pierre Lozi, Iraklis Psaroudakis, Alexander Weld, Dalila Chiadmi, Sungpack Hong, and Hassan Chafi. CSR++: A Fast, Scalable, Update-Friendly Graph Data Structure. In 24th International Conference on Principles of Distributed Systems (OPODIS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 184, pp. 17:1-17:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{firmli_et_al:LIPIcs.OPODIS.2020.17,
  author =	{Firmli, Soukaina and Trigonakis, Vasileios and Lozi, Jean-Pierre and Psaroudakis, Iraklis and Weld, Alexander and Chiadmi, Dalila and Hong, Sungpack and Chafi, Hassan},
  title =	{{CSR++: A Fast, Scalable, Update-Friendly Graph Data Structure}},
  booktitle =	{24th International Conference on Principles of Distributed Systems (OPODIS 2020)},
  pages =	{17:1--17:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-176-4},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{184},
  editor =	{Bramas, Quentin and Oshman, Rotem and Romano, Paolo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2020.17},
  URN =		{urn:nbn:de:0030-drops-135021},
  doi =		{10.4230/LIPIcs.OPODIS.2020.17},
  annote =	{Keywords: Data Structures, Concurrency, Graph Processing, Graph Mutations}
}
Document
DOI: 10.4230/LITES-v001-i002-a001
Blocking Optimality in Distributed Real-Time Locking Protocols

Authors: Björn Bernhard Brandenburg

Published in: LITES, Volume 1, Issue 2 (2014). Leibniz Transactions on Embedded Systems, Volume 1, Issue 2

Abstract
Lower and upper bounds on the maximum priority inversion blocking (pi-blocking) that is generally unavoidable in distributed multiprocessor real-time locking protocols (where resources may be accessed only from specific synchronization processors) are established. Prior work on suspension-based shared-memory multiprocessor locking protocols (which require resources to be accessible from all processors) has established asymptotically tight bounds of Ω(m) and Ω(n) maximum pi-blocking under suspension-oblivious and suspension-aware analysis, respectively, where m denotes the total number of processors and n denotes the number of tasks. In this paper, it is shown that, in the case of distributed semaphore protocols, there exist two different task allocation scenarios that give rise to distinct lower bounds. In the case of co-hosted task allocation, where application tasks may also be assigned to synchronization processors (i.e., processors hosting critical sections), Ω(Φ · n) maximum pi-blocking is unavoidable for some tasks under any locking protocol under both suspension-aware and suspension-oblivious schedulability analysis, where Φ denotes the ratio of the maximum response time to the shortest period. In contrast, in the case of disjoint task allocation (i.e., if application tasks may not be assigned to synchronization processors), only Ω(m) and Ω(n) maximum pi-blocking is fundamentally unavoidable under suspension-oblivious and suspension-aware analysis, respectively, as in the shared-memory case. These bounds are shown to be asymptotically tight with the construction of two new distributed real-time locking protocols that ensure O(m) and O(n) maximum pi-blocking under suspension-oblivious and suspension-aware analysis, respectively.
Cite as

Björn Bernhard Brandenburg. Blocking Optimality in Distributed Real-Time Locking Protocols. In LITES, Volume 1, Issue 2 (2014). Leibniz Transactions on Embedded Systems, Volume 1, Issue 2, pp. 01:1-01:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2014)

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@Article{brandenburg:LITES-v001-i002-a001,
  author =	{Brandenburg, Bj\"{o}rn Bernhard},
  title =	{{Blocking Optimality in Distributed Real-Time Locking Protocols}},
  journal =	{Leibniz Transactions on Embedded Systems},
  pages =	{01:1--01:22},
  ISSN =	{2199-2002},
  year =	{2014},
  volume =	{1},
  number =	{2},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v001-i002-a001},
  URN =		{urn:nbn:de:0030-drops-192479},
  doi =		{10.4230/LITES-v001-i002-a001},
  annote =	{Keywords: Distributed multiprocessor real-time systems, Real-time locking, Priority inversion, Blocking optimality}
}
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