| 摘要 |
PURPOSE:To efficiently execute instructions by providing each subchannel with an information block having an input/output instruction direct execution flag, which indicates whether the subchannel is monopolized by a guest or not, and a guest identifier which indicates the monopolizing guest. CONSTITUTION:When an input/output instruction is issued from one of guests 1-3, an input/output instruction processing mechanism 120 checks one of information blocks 11-13 which is related to the subchannel designated by the input/output instruction. If an input/output direct instruction execution flag DIOF of this information block indicates monopolization and a guest identifier GID coincides with the identifier of the guest of the instruction issue source, the guest of the instruction issue source is caused to directly execute the input/ output issue source is caused to directly execute the input/output instruction. If the input/output instruction direct execution flag DIOF of the information block does not indicate monopolization, processing to take out the indicate monopolization, processing to take out the input/output instruction to a host 10 is performed. Thus, input/output instructions and TPI instructions which guests issue are efficiently executed to reduce the overhead. |
