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Single Entry Buffer for I/O Interrupts

IP.com Disclosure Number: IPCOM000049777D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Walters, RT: AUTHOR

Abstract

A fast access buffer holds the information for an I/O interrupt. If a subsequent interrupt occurs before the first interrupt has been cleared, the subsequent interrupt is enqueued conventionally in I/O processor storage by establishing an address pointer to the control block for the subchannel that is associated with the interrupt. An interrupt that is identified in the buffer is cleared first and any entries in the queue are cleared afterwards. A new entry is not made in the buffer unless the buffer and the queue are both empty. In a data processing system in which on the average there is only one pending interrupt, the buffer improves performance.

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Single Entry Buffer for I/O Interrupts

A fast access buffer holds the information for an I/O interrupt. If a subsequent interrupt occurs before the first interrupt has been cleared, the subsequent interrupt is enqueued conventionally in I/O processor storage by establishing an address pointer to the control block for the subchannel that is associated with the interrupt. An interrupt that is identified in the buffer is cleared first and any entries in the queue are cleared afterwards. A new entry is not made in the buffer unless the buffer and the queue are both empty. In a data processing system in which on the average there is only one pending interrupt, the buffer improves performance.

Conventionally, an I/O interrupt becomes pending at the end of an I/O operation, and the interrupt is cleared when it is feasible to switch from a program currently being executed in the central processor to a program for handling the interrupt. When more than one interrupt becomes pending, it is conventional to enqueue the associated subchannels. Such a queue has the advantage that it can be made quite long without significant additional storage space, but it requires time for the operations for managing the queue. The buffer reduces the time required for queue management but preserves the advantege of a long queue when one is required.

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