Lux

A distributed multi-GPU system for fast graph processing.

Prerequisites

• CUDA is used to implemented Lux.

• CUB is used as an external submodule for Lux's tasks.

• Legion is the underlying runtime for launching tasks and managing data movement.

• (Optional) GASNet is used for multi-node executions. (see installation instructions)

After you have cloned Lux, use the following command lines to clone CUB and Legion.

git submodule init
git submodule update

Compilation

• Download Lux source code:

# Using git to download Lux
git clone --recursive https://github.com/LuxGraph/Lux

• Compile a Lux application (e.g., PageRank):

cd pagerank
make clean; make -j 4

• To build a distributed version of Lux, set USE_GASNET flag and rebuild:

make clean
USE_GASNET=1 make -j 4

Running code

The applications take an input graph as well as several runtime flags starting with -ll:. For example:

./pagerank -ll:gpu 4 -ll:fsize 12000 -ll:zsize 20000 -file twitter-2010.lux -ni 10
./components -ll:gpu 1 -ll:fsize 6000 -ll:zsize 6000 -file indochina.lux -verbose -check
./sssp -ll:gpu 2 -ll:fsize 12000 -ll:zsize 20000 -file twitter-2010.lux -start 0

• -ll:gpu: number of GPU processors to use in an execution
• -ll:fsize: size of framebuffer memory for each GPU (in MB)
• -ll:zsize: size of zero-copy memory (pinned DRAM with direct GPU access) on each node (in MB)
• -file: path to the input graph
• -ni: number of iterations to perform
• -start: root vertex for SSSP
• -verbose: show detailed task execution information
• -check: perform correctness check after computation

Graph Format

Lux uses compressed sparse column (CSC) graph in binary format. The specific format is as follows in binary:

<nv>
<ne>
<c0>
<c1>
...
<c(nv-1)>
<e0>
<e1>
...
<e(ne-1)>

<nv> and <ne> denote the number of vertices and direct edges in the graph. The CSC format starts with a sequence of offsets for the vertices in the CSC format, followed by a sequence of directed edges ordered by their target vertex. The offset <c(i-1) and <c(i)> refer to the start and end points of a contiguous block of in-edges for vertex i. More specifically, <e(c(i-1))>...<e(c(i)-1)> is the collection of all in-neighbors for vertex i. For weighted graphs, the weights are stored after the edge sources.

Some example graphs in Lux format are as follows.

Graph	NV	NE	Weighted
Hollywood	1,139,905	57,515,616
Indochina	7,414,866	194,109,311
Twitter-2010	41,652,230	1,468,365,182
RMAT27	134,217,728	2,147,483,648
Amazon	3,376,972	11,676,082	Yes
NetFlix	497,959	200,961,014	Yes

Publication

Zhihao Jia, Yongkee Kwon, Galen Shipman, Pat McCormick, Mattan Erez, and Alex Aiken. A Distributed Multi-GPU System for Fast Graph Processing. PVLDB 11(3), 2017.