Monitoring Return From Interrupts by a Performance Monitor
Original Publication Date: 1988-Apr-01
Included in the Prior Art Database: 2005-Feb-15
A method for monitoring the completion of interrupt-level events for the Personal Computer (PC) is described. In the past, PC monitors have only been able to record the beginning of an arbitrary interrupt event. This has prevented performance analysts from measuring the actual time taken by each interrupt event, such as a disk read or a network handshake. Instead, they normally could only trace the beginning of each such event. To record the start of an arbitrary interrupt in a software monitor, the interrupt vector table is changed so that the monitoring code is executed before the particular interrupt service routine is executed. For instance, all disk activity uses the Basic Input Output System (BIOS) routine, accessed through vector 13 (hex) in the interrupt vector table.