Thrifty Label Propagation: Fast Connected Components for Skewed-Degree Graphs – IEEE CLUSTER’21

IEEE CLUSTER 2021

IEEE CLUSTER 2021
7-10 September

Acceptance rate: 29.4%

DOI: 10.1109/Cluster48925.2021.00042
IEEE Xplore
PDF Version (Authors’ Copy)

Thrifty introduces four optimization techniques to Label Propagation Connected Components:

1) Unified Labels Array accelerates label propagation by allowing the latest label of each vertex to be read in processing other vertices.

2) Zero Convergence optimizes work-efficiency in the pull iterations of Label Propagation by skipping converged vertices.

3) Zero Planting selects the best start propagating point and increases the convergence rate and removes pull iterations that are required for the lowest label to reach the core of graph.

4) Initial Push technique makes the first iteration work efficient by skipping processing edges of vertices that probability of convergence is very small.

Based on these optimizations, Thrifty provides 1.4✕ speedup to Afforest, 6.6✕ to Jayanti-Tarjan, 14.3✕ to BFS-CC, and 25.0✕ to Direction Optimizing Label Propagation.

  • Thrifty Label Propagation: Fast Connected Components For Skewed Degree Graphs
  • Thrifty Label Propagation: Outline
  • Thrifty Label Propagation: Background
  • Thrifty Label Propagation: Background
  • Thrifty Label Propagation: Background
  • Thrifty Label Propagation
  • Thrifty Label Propagation: Unified Labels Array
  • Thrifty Label Propagation: Unified Labels Array
  • Thrifty Label Propagation: Zero Convergence
  • Thrifty Label Propagation: Zero Convergence
  • Thrifty Label Propagation: Zero Planting
  • Thrifty Label Propagation: Zero Planting
  • Thrifty Label Propagation:  Initial Push
  • Thrifty Label Propagation:  Evaluation
  • Thrifty Label Propagation:  Evaluation
  • Thrifty Label Propagation:  Evaluation
  • Thrifty Label Propagation:  Conclusion
  • Thrifty Label Propagation:  Thanks
  • Thrifty Label Propagation:  A Gift from QUB


Code Availability
The source-code of Thrifty is available on LaganLighter Repository (alg2_thrifty.c and cc.c files). A sample execution of this source code for “Twitter-MPI” graph is shown in the following:


Bibtex

@INPROCEEDINGS{10.1109/Cluster48925.2021.00042,
  author={Koohi Esfahani, Mohsen and Kilpatrick, Peter and Vandierendonck, Hans},
  booktitle={2021 IEEE International Conference on Cluster Computing (CLUSTER)}, 
  title={Thrifty Label Propagation: Fast Connected Components for Skewed-Degree Graphs}, 
  year={2021},
  volume={},
  number={},
  pages={226-237},
  publisher={IEEE Computer Society},
  doi={10.1109/Cluster48925.2021.00042}
}

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Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing – ICPP’21

ICPP'21

50th International Conference on Parallel Processing (ICPP’21)
August 9-12, 2021

Acceptance Rate: 26.4%

DOI:10.1145/3472456.3472462
ACM Digital Library
PDF Version (Authors’ Copy)

This paper investigates the implications made by the structure of real-world graphs with power-law degree distribution on the locality of SpMV graph analytics, and by considering the efficacy of locality optimizing graph reordering algorithms (such as SlashBurn, GOrder, and Rabbit-Order) shows that irregular datasets requires special traversals in order to improve locality for hub vertices that dedicate a large portion of the processing time to themselves.

We introduce in-Hub Temporal Locality (iHTL) as a structure-aware and cache-friendly graph traversal that optimizes locality in pull traversal. iHTL identifies different blocks in the adjacency matrix of a graph and applies a suitable traversal direction (push or pull) for each block based on its contents. In other words, iHTL optimizes locality of one traversal of all edges of the graph by:

(1) applying push direction for flipped blocks containing edges to in-hubs, and
(2) applying pull direction for processing sparse block containing edges to non-hubs.

Moreover, iHTL introduces a new algorithm to efficiently identify the number of flipped blocks by investigating connection between hub vertices of the graph. This allows iHTL to create flipped blocks as much as the graph structure requires and makes iHTL suitable for a wide range of different real-world graph datasets like social networks and web graphs.

iHTL is 1.5× – 2.4× faster than pull and 4.8× – 9.5× faster than push in state-of-the-art graph processing frameworks. More importantly, iHTL is 1.3× – 1.5× faster than pull traversal of state-of-the-art locality optimizing reordering algorithms such as SlashBurn, GOrder, and Rabbit-Order while reduces the preprocessing time by 780×, on average.

  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : Outline
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : Introduction
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : Pull vs Push
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : Is Pull A Suitable Direction
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : iHTL: in-Hub Temporal Locality
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : iHTL Graph Structure
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : SpMV in iHTL
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph Processing : Evaluation
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph : Conclusion
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph : Thanks
  • Exploiting in-Hub Temporal Locality in SpMV-based Graph : A Gift From QUB

Code Availability
The source-code will be published soon.

BibTex


@INPROCEEDINGS{10.1145/3472456.3472462,
author = {Koohi Esfahani, Mohsen and Kilpatrick, Peter and Vandierendonck, Hans},
title = {Exploiting In-Hub Temporal Locality In SpMV-Based Graph Processing},
year = {2021},
isbn = {9781450390682},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
url = {https://doi.org/10.1145/3472456.3472462},
doi = {10.1145/3472456.3472462},
booktitle = {50th International Conference on Parallel Processing},
numpages = {10},
location = {Lemont, IL, USA},
series = {ICPP 2021}
}

LaganLighter

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How Do Graph Relabeling Algorithms Improve Memory Locality? ISPASS’21 (Poster)

IEEE Xplore (DOI: 10.1109/ISPASS51385.2021.00023)
ISPASS-2021
2021 IEEE International Symposium on Performance Analysis of Systems and Software
March 28-30, 2021

Authors’ Copy (PDF Format)

For a complete version of this article, please refer to Locality Analysis of Graph Reordering Algorithms and also Chapter 3 of the On Designing Structure-Aware High-Performance Graph Algorithms thesis.

Relabeling (reordering) algorithms aim to improve the poor memory locality of graph processing by changing the order of vertices. This paper analyses the functionality of three state-of-the-art relabeling algorithms: SlashBurn, GOrder, and Rabbit-Order for real-world graphs.

We use a number of techniques to explain how locality is affected by relabeling algorithms and how locality of different datasets (like social networks and web graphs) is enhanced by relabeling algorithms.

We use last level cache simulation to study miss rate degree distribution. We also use the degree distribution of Giant Connected Component (GCC) in SlashBurn iterations to see if real-world graphs follow the assumption that “power-law graphs are created/destroyed recursively” [SlashBurn]. We represent SlashBurn++ as an enhanced version of SlashBurn with lower preprocessing time and better locality.

Using cache simulation, we count the number of misses for accessing vertices data of high-degree vertices. This helps to explain how GOrder provides better temporal locality by managing cache space. Average ID Distance (AID) is a spatial locality metric introduced in this paper to explain how clustering relabeling algorithms like Rabbit-Order provide better spatial locality.

This paper also investigates why push and pull traversals of different datasets show different performances by introducing Push Locality and Pull Locality.

Code Availability
The source-code of LaganLighter is available on LaganLighter Repository.

BibTex

@INPROCEEDINGS{10.1109/ISPASS51385.2021.00023,
  author={Koohi Esfahani, Mohsen and Kilpatrick, Peter and Vandierendonck, Hans},
  booktitle={2021 IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS)}, 
  title={How Do Graph Relabeling Algorithms Improve Memory Locality?}, 
  year={2021},
  volume={},
  number={},
  pages={84-86},
  publisher={IEEE Computer Society},
  doi={10.1109/ISPASS51385.2021.00023}
}

ISPASS’21
ISPASS’21 Final Program
LaganLighter

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