The most important notation that summarizes a queue:

• ρ: utilization ratio = λ / μ

Examples:

• ρ = 1 means the arrival rate is equal to the service rate; the queue is staying the same size.

• ρ > 1 means the arrival rate is greater than the service rate; the queue is getting larger.

• ρ < 1 means the arrival rate is less than the service rate; the queue is getting smaller.

Queueing theory
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