Cost modelling

The time cost to transfer a data packet between two nodes consists of two parts:

• A fixed overhead or latency, $\alpha$, which is independent of the amount of data sent.
• The time to transmit the data between the nodes, which depends upon the bandwidth of the connection, $\beta$, and the size of the data packet.

Notation:

• $n = n_x n_y n_z$ is the full FFT grid size.
• The number of nodes is $N$.