ParGol runs Conway's Game of Life, using MPI, in a straightforward way that is easy to parallelize further with threads. Additionally, It requires tasking and overlapping of communication and computation for best performance. The goal of ParGol is to create a small, easy-to-understand, but non-trivial, application that can be used to test the performance of different threading frameworks.
Usage: ./pargol [input file] [no. generations] [print size] [print frequency]
Example input files are included. Each contains a header with two numbers, size
and number of repetitions. The first gives the size n of the game board given in
the input file, where n is the number of rows and columns (game board must be
a square). The full board size will be nr x nr, where r is the number of
repetitions. The remainder of the file is the game board (see examples). Note
that only the asterisk indicates a live cell. So any other character can be
used for the other cells.
The number of generations indicates the number of iterations of the game to run.
The print size is optional and is the number of rows and columns to print.
Default size is 100.
The print frequency, p, is also optional. By default, only the first and last
generations are printed. If given, the board is printed every p iterations
(1 prints all iterations, 2 every other iteration, etc.).
The number of MPI ranks must be a perfect square and must evenly divide the
game board (size of game board must be divisible by the square root of the
number of ranks).
For threading, modify the "next_gen" function, which consists of three parts,
computing internal cells, communication, and computing external cells. The only
dependency is that step 2 must be done before step 3. Thus, you can test tasking
strategies and overlapping of computation and communication. Note that, with
a sufficiently large board, the internal cell computations dwarf the external
computations (quadratic vs linear growth), and thus overlapping the first two
steps becomes key.