| 摘要 |
An I/O control system in a virtual machine system has at least one virtual machine (VM) running under control of a virtual machine control program (VMCP) and has a direct I/O execution mode in which an I/O interruption to the I/O device dedicated by the running VM is directly executed without intervention of the VMCP and an indirect I/O execution mode in which the I/O interruption is simulated. The I/O control system comprises identification portion for identifying the I/O device requesting the switching to the direct I/O execution mode, judge portion for judging a mode switching condition and mode selection portion for selecting one of the two modes. If the VM which contemplates the direct execution has not yet dedicated the I/O device requesting the mode switching, it dedicates the I/O device, and if the VM has not yet dedicated an I/O interrupt subclass which controls the I/O interruption of the I/O device, it dedicates the subclass, and the I/O device in the indirect I/O execution mode is switched to the direct I/O execution mode.
|
