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WAITing for One of n Events

IP.com Disclosure Number: IPCOM000079178D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Gum, PH: AUTHOR

Abstract

A number of system components, as well as application programs, utilize the IBM OS/360 list form of the WAIT macro to request various services from other components. Execution of the calling component continues until the results of one or more of the requested services are needed, at which time a search of completed ECB's (Event Control Blocks) is made. ECB's are posted by the called routines when their operation is complete, thus providing the communication mechanism between routines.

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WAITing for One of n Events

A number of system components, as well as application programs, utilize the IBM OS/360 list form of the WAIT macro to request various services from other components. Execution of the calling component continues until the results of one or more of the requested services are needed, at which time a search of completed ECB's (Event Control Blocks) is made. ECB's are posted by the called routines when their operation is complete, thus providing the communication mechanism between routines.

The list form of the WAIT macro is typically used by system components managing communication lines or a data base and in such case, it is not unusual for the list to designate 100 to 200 ECB's. Usually, the calling component specifies that it is to resume execution when any one ECB has been posted, although another technique is to dynamically construct the list of active ECB's prior to each issuance of WAIT. This latter technique results from the observation that, while the wait list may contain the addresses of all ECB's that might potentially be posted, the probability of a post occurring for some of them is very low. The performance cost in the latter technique is the expense of continually dynamically constructing a list and then searching it after waiting to find the posted ECB while in the former case, construction time is saved at the expense of searching a longer list, first by the system wait routine and then by the caller after wait.

This description involves a modification to the OS/360 list form of the WAIT macro, to provide an identifier as...