CSC485b Fall 2024 A2

Johnathan Warawa & Emily Martins

Prerequisites

You should have a functional CUDA environment installed with a GPU of compute capability 7.5 or higher. Our code is best optimized for the Turing architecture, but has been tested to work on Ampere.

OpenBLAS is helpful for checking correctness of output, but not necessary. See the 'Build' section for more details.

Build

A makefile is provided in the top-level directory which handles building the application. The default target is sm_75 (eg, Compute Capability 7.5 graphics cards such as the Turing T4).

$ make

To specify the arch string for your target, use the TARGET variable when calling make. For example, for a Compute Capability 8.6 graphics card such as the RTX 3060, use:

$ make TARGET=sm_86

The following options may also be specified using environment variables:

• USE_OPENBLAS=yes: By default, the OpenBLAS library is called to perform a CPU matrix multiplication to serve as a baseline to check for correctness. If you do not have OpenBLAS on your system, set this variable to no to use a naive provided n^3 CPU implementation.
• OPENBLAS_NUM_THREADS=$(nproc): If USE_OPENBLAS=yes, this option can be specified to reduce the number of threads used by OpenBLAS.
• USE_FULL_MULTIPLY=no: Set to yes to use the less-optimized full-multiply dense two_hop_reachability, otherwise use the more-optimized just-set-one implementation (the one described as 'clever' in our video) for dense.
• USE_WARP_PRIMITIVES=yes: If using full multiply, set to no to use an unoptimized solution which does not exploit warp primitives.

A clean is required before switching configurations.

Run

A single executable, a2 is generated. Simply run this file.

For debugging and output inspection, a2 provides a -p argument. When this argument is provided, a printed output of the generated edge list in addition to both expected and actual outputs for both dense and CSR implementations is produced.