Aggregate bandwidth and throughput of synchronous dual-ports

Question: - How do you calculate bandwidth with dual-ports? - What is the throughput of a particular dual-port?

 

Answer:

To transfer data through the device, both write and read operations are required.

Aggregate bandwidth is the total data transfer rate of both device ports. Aggregate Bandwidth = N * W * fmax

Aggregate throughput is the total data transfer rate through the device.  Aggregate Throughput = (N * W * fmax) / 2 --> N = Number of Ports = 2 --> W = Port Width --> fmax = maximum port operating frequency

For synchronous, pipelined dual-ports, the aggregate throughput equation above is the best-case that occurs when one port is dedicated to writing and the other is dedicated to reading. Turning around a port from reading-to-writing or writing-to-reading typically results in NOP cycles that degrade throughput. As long as read and writes occur in large bursts, the reduction in throughput is relatively small.