The duration of a lock is the average number of instructions executed while the lock is held. The execution interval of a lock is the average number of instructions executed between successive requests for that lock by a process. The collision cross section of the lock is the fraction of time it is granted, i.e., the lock grant probability.

Most of us are stuck with a pre-emptive scheduler (i.e., general purpose operating system with virtual memory). Hence convoys will occur. The problem is to make them evaporate quickly when they do occur rather than have them persist forever.