Apparatus and method for computer host system and adaptor interrupt reduction including clustered command completion

The invention provides structure and method to control the presentation of interrupts to a computer system by delaying communication of the interrupts to the host computer or processor according to predetermined rules. In particular, the method of the invention first detects the occurrence of an I/O interrupt related to a device. Next, the method reserves notification to the host processor of the I/O interrupt for a period of time based on a set of predetermined rules. Finally, the method notifies the host processor of substantially all I/O interrupts for which notification has been reserved during the period of time at expiration of the period of time, whereby the reserve notification lowers the overhead to the host processor in handling the I/O interrupts.