In addition to separating read and write operations, we must decide exactly what to
measure. It may seem that the most important measure is latency (i.e., the time that
elapses between the start of an operation and the completion of the operation). However,
latency is a simplistic measure that does not provide complete information.
To see why latency does not suffice as a measure of memory performance, we
need to understand how the hardware works. In addition to the memory chips themselves,
additional hardware known as a memory controller provides an interface†. Figure
10.3 illustrates the organization.