| 摘要 |
PURPOSE:To perform approximately even tests to all I/O devices in a short time by giving the preference service in the next time to the I/O device having the minimum service frequency among plural I/O devices when the service is not successful. CONSTITUTION:A scheduler performs the sequential services through an I/O control table indicated by an I/O preference service pointer 42 to perform a test of an I/O device. In such a case, an I/O service counter 52 showing the service frequency of said I/O device is replaced when this I/O device receives the service. If the service is not successful, the pointer 42 is switched so that the relevant I/O control table is indicated in case the value of the counter 52 of the relevant I/O device is smallest among those I/O device connected to the same channel. In such a way, all I/O device connected to the same channel can receive the services evenly in a short time. |
