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Measuring Frequency of Entering a Control Section

IP.com Disclosure Number: IPCOM000077091D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gasich, DB: AUTHOR [+2]

Abstract

The problem of finding how often an entry into a CSECT is made is similar to the problem of finding how often an instruction is executed. The instruction execution is detected, for example, by replacing opcode of an instruction by Hex 00 which will, when executed, cause the operation exception. All operation exceptions are intercepted and, if the exception occurred at the known location, then it is handled appropriately.

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Measuring Frequency of Entering a Control Section

The problem of finding how often an entry into a CSECT is made is similar to the problem of finding how often an instruction is executed. The instruction execution is detected, for example, by replacing opcode of an instruction by Hex 00 which will, when executed, cause the operation exception. All operation exceptions are intercepted and, if the exception occurred at the known location, then it is handled appropriately.

The method described here offers detection of entering into a module without effecting program interrupt handler. The method also offers a means for identifying the CSECT name by detecting it from the name field which is available in the majority of CSECT's. (Those which begin with a SAVE macro.)

The changes are made to the load module at the entry point of each CSECT by replacing branch instruction by a user SVC. There is no change to the operating system. The method requires a user SVC to be added to the SVCLIB.

An entry into the CSECT is signalled by issuance of the user SVC. The number of SVC's could be counted to find frequency of entry into a module. The SVC can be written to collect count of entries into a CSECT identified by its name and several names can be monitored simultaneously.

A variation on this concept would be signalling the return from a CSECT using another user SVC.

The SVC tracing programs can be used to detect entry or exit of a CSECT with a time stamp, for the purpose of eit...