GBBS: Graph Based Benchmark Suite

Organization

This repository contains code for our SPAA paper "Theoretically Efficient Parallel Graph Algorithms Can Be Fast and Scalable" (SPAA'18). It includes implementations of the following parallel graph algorithms:

Connectivity Problems

Low-Diameter Decomposition
Connectivity
Spanning Forest
Biconnectivity
Minimum Spanning Tree
Strongly Connected Components

Covering Problems

Coloring
Maximal Matching
Maximal Independent Set
Approximate Set Cover

Eigenvector Problems

PageRank

Substructure Problems

Triangle Counting
Approximate Densest Subgraph
k-Core (coreness)

Shortest Path Problems

Unweighted SSSP (Breadth-First Search)
General Weight SSSP (Bellman-Ford)
Integer Weight SSSP (Weighted Breadth-First Search)
Single-Source Betweenness Centrality
Single-Source Widest Path
k-Spanner

The code for these applications is located in the benchmark directory. The implementations are based on the Ligra/Ligra+/Julienne graph processing frameworks. The framework code is located in the src directory.

The codes used here are still in development, and we plan to add more applications/benchmarks. We currently include the following extra codes, which are part of ongoing work.

experimental/KTruss

If you use our work, please cite our paper:

@inproceedings{dhulipala2018theoretically,
  author    = {Laxman Dhulipala and
               Guy E. Blelloch and
               Julian Shun},
  title     = {Theoretically Efficient Parallel Graph Algorithms Can Be Fast and
               Scalable},
  booktitle = {ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)},
  year      = {2018},
}

Compilation

g++ >= 5.3.0 with support for Cilk Plus
g++ >= 5.3.0 with pthread support (Homemade Scheduler)

The default compilation uses Cilk Plus. We also support a lightweight scheduler developed at CMU (Homemade), which results in comparable performance to Cilk. The half-lengths for certain functions such as histogramming are lower using Homemade, which results in better performance for codes like KCore.

Note: The Homemade scheduler was developed after our paper submission. For reproducibility purposes, the codes should be compiled with Cilk Plus, although in our experience the times are usually faster using Homemade.

The benchmark supports both uncompressed and compressed graphs. The uncompressed format is identical to the uncompressed format in Ligra. The compressed format, called bytepd_amortized (bytepda) is similar to the parallelByte format used in Ligra+, with some additional functionality to support efficiently packs, filters, and other operations over neighbor lists.

To compile codes for graphs with more than 2^32 edges, the LONG command-line parameter should be set. If the graph has more than 2^32 vertices, the EDGELONG command-line parameter should be set. Note that the codes have not been tested with more than 2^32 vertices, so if any issues arise please contact Laxman Dhulipala.

To compile using the Homemade scheduler the HOMEMADE command-line parameter should be set. If it is unset, the Cilk Plus scheduler is used by default.

After setting the necessary environment variables:

$ make -j  #compiles the benchmark with all threads

The following commands cleans the directory:

$ make clean  #removes all executables

Running code

The applications take the input graph as input as well as an optional flag "-s" to indicate a symmetric graph. Symmetric graphs should be called with the "-s" flag for better performance. For example:

$ ./BFS -s -src 10 ../inputs/rMatGraph_J_5_100
$ ./wBFS -s -w -src 15 ../inputs/rMatGraph_WJ_5_100

Note that the codes that compute single-source shortest paths (or centrality) take an extra -src flag. The benchmark is run four times by default, and can be changed by passing the -rounds flag followed by an integer indicating the number of runs.

On NUMA machines, adding the command "numactl -i all " when running the program may improve performance for large graphs. For example:

$ numactl -i all ./BFS -s <input file>

Running code on compressed graphs

We make use of the bytePDA format in our benchmark, which is similar to the parallelByte format of Ligra+, extended with additional functionality. We have provided a converter utility which takes as input an uncompressed graph and outputs a bytePDA graph. The converter can be used as follows:

./compressor -s -o ../inputs/rMatGraph_J_5_100.bytepda ../inputs/rMatGraph_J_5_100
./compressor -s -w -o ../inputs/rMatGraph_WJ_5_100.bytepda ../inputs/rMatGraph_WJ_5_100

After an uncompressed graph has been converted to the bytepda format, applications can be run on it by passing in the usual command-line flags, with an additional -c flag.

$ ./BFS -s -c -src 10 ../inputs/rMatGraph_J_5_100.bytepda
$ ./wBFS -s -w -c -src 15 ../inputs/rMatGraph_WJ_5_100.bytepda

When processing large compressed graphs, using the -m command-line flag can help if the file is already in the page cache, since the compressed graph data can be mmap'd. Application performance will be affected if the file is not already in the page-cache. We have found that using -m when the compressed graph is backed by SSD results in a slow first-run, followed by fast subsequent runs.

Input Formats

We support the adjacency graph format used by the Problem Based Benchmark suite and Ligra.

The adjacency graph format starts with a sequence of offsets one for each vertex, followed by a sequence of directed edges ordered by their source vertex. The offset for a vertex i refers to the location of the start of a contiguous block of out edges for vertex i in the sequence of edges. The block continues until the offset of the next vertex, or the end if i is the last vertex. All vertices and offsets are 0 based and represented in decimal. The specific format is as follows:

AdjacencyGraph
<n>
<m>
<o0>
<o1>
...
<o(n-1)>
<e0>
<e1>
...
<e(m-1)>

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