Browse Prior Art Database

Management of Input-Output Buffers

IP.com Disclosure Number: IPCOM000041829D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Meacock, G: AUTHOR

Abstract

This article describes a method of managing input-output (I/O) buffers in which cross-chains of buffers are used to reduce the number of I/O buffers that have to be searched. In a busy database-data communication system, such as the IBM Customer Information Control System (CICS/VS), there will be very few, if any, I/O buffers having a state of unallocated/empty. (See the preceding article). This means that a search for the I/O buffer containing the copy of control interval 'n' is likely to become a search of all of the I/O buffers. In order to reduce the search it is noted that a control interval will, at any instant, hold records for one and only one queue and thus it becomes possible to regard an I/O buffer (with a state unallocated/valid or allocated) as being associated with a specific queue.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 77% of the total text.

Page 1 of 2

Management of Input-Output Buffers

This article describes a method of managing input-output (I/O) buffers in which cross-chains of buffers are used to reduce the number of I/O buffers that have to be searched. In a busy database-data communication system, such as the IBM Customer Information Control System (CICS/VS), there will be very few, if any, I/O buffers having a state of unallocated/empty. (See the preceding article). This means that a search for the I/O buffer containing the copy of control interval 'n' is likely to become a search of all of the I/O buffers. In order to reduce the search it is noted that a control interval will, at any instant, hold records for one and only one queue and thus it becomes possible to regard an I/O buffer (with a state unallocated/valid or allocated) as being associated with a specific queue. A second control block, the multiple queue control block (MQCB) is associated with each I/O buffer. MQCBs are used to chain I/O buffers containing data for a given queue to a control block for the queue. The rules then become for non- empty control intervals. 1. Search the queue specific chain for control interval 'n'.
2. "Pop" the unallocated/empty chain. 3. "Dequeue" the unallocated/valid chain. This reduces the number of I/O buffers that have to be searched for a given control interval when several queues are being processed at the same time. The MQCB chain is organized in order of most recently used to least recently used, making it...