 Workload of a queue

The queue workload of a queue is the total remaining service work of all present customers, including residual work in service. With a work-conserving server of rate $C$ and stationary input $A$, the stationary queue workload is represented byThis is the amount by which past offered work exceeds available service, maximized over possible starts of a busy period. It is the reflection of net input at zero. Under first come first served, an arriving infinitesimal customer waits $W/C$; a priority customer instead waits for the remaining work ahead of it under its service discipline.