ACT Transaction Residency Time
Transaction residency time attempts to measure the time a transaction is active in the processor for interactive systems such as CICS and IMS.
rm
The following diagram explains this measurement:
task task _____ attached detached ______ | | | | | | |_____| | | |______| | | | | | input | | | | output message -------->| |<__________>| | ------------ message Transaction Residency
When a message enters the system, it is transmitted to the CPU, where it resides until the processing completes. The period between the time of input and the time the task is attached is not included in transaction residency time, nor is the period between the time the task is detached from the CPU and the time the output message is received.
Because transaction residency time is dependent on the multiprogramming mix, it varies with the performance of the computer and the number of other transactions in the system. As the same task does not always have the same transaction residency time, it is an inconsistent, and therefore unsatisfactory, method of measurement.