A page fault results in disk I/Os. Such I/Os are known as fault I/Os.
Compare with soft page fault.
Subprocesses that do interactive work are reclassified as interactive.
This reclassification may also occur for detached processes. A batch job issuing a broadcast message is not classified as interactive.
For other interactive transactions, such as those that occur within editors, an interactive transaction may consist of a single keystroke or a complete editor command. For example, every keystroke on input is an interactive transaction; an editor FIND command is an interactive transaction.
In MAIL, a SEND command is terminated when the TO: prompt appears, signifying the completion of one interactive transaction and the start of another. With the SEND/EDIT command, every character entered is an interactive transaction.
An interactive transaction is defined as any keyboard sequence (one or more commands or keystrokes) that results in consumption of CPU and other system resources. Typical examples are commands (terminated by pressing the Return key) and editing keystrokes. A transaction is a response and think time pair.
The relationship between transaction, response time, and think time is illustrated in the Figure, Response Time, Think Time, and Transaction.
The first RETURN (far left) indicates the end of input (for example, the terminator for the last command, an editor prompt, or a cursor flash); the dollar prompt indicates that the system has processed the command and is ready for further input; while the last (far right) RETURN indicates the end of the next input (for example, the terminator for the next command). This diagram is specifically geared toward DCL commands; in an editor, the end of a command is any keystroke or escape sequence.
Reaction time is not measured by the PerfCap Capacity Planner (time from end of input to display of first response character from system). Think time includes time spent by the terminal user in thinking about the previous output, determining what to do next, and in typing the next command. Since a portion of think time is spent in examining the previous output, a transaction is depicted as a response- and think-time pair rather than a think- and response-time pair.
See also response time and think time.