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Improve Performance of VM Gateway Host Polling

IP.com Disclosure Number: IPCOM000109807D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 56K

Publishing Venue

IBM

Related People

Boeving, RD: AUTHOR [+3]

Abstract

This article describes a method for improving the performance of applications using High Level Application Programming Interface (HLAPPI) to communicate with the VM host. Ways have been created that significantly reduce the performance impact that host polling has on the PC and the host involved in HLAPPI communication.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 56% of the total text.

Improve Performance of VM Gateway Host Polling

       This article describes a method for improving the
performance of applications using High Level Application Programming
Interface (HLAPPI) to communicate with the VM host.  Ways have been
created that significantly reduce the performance impact that host
polling has on the PC and the host involved in HLAPPI communication.

      A normal HLAPPI application makes a copy of what is shown on
the host screen and attempts to match character strings.  If the
appropriate character string is not found on the host screen, then a
loop is entered and execution is paused until the string appears on
the host screen.  During the wait loop the screen is continually
polled to catch any updates.  For a slow machine such a loop can poll
the host up to 18 times a second and even more often with the faster
PCs.  Normally, the application will continue the loop for a
specified amount of time, and if the specified character string does
not appear on the host screen in the specified amount of time, then
the program execution is terminated.  The host polling takes a
considerable amount of the CPU cycles, and the performance of other
tasks that should be taking place on the server are adversely
affected.  The excessive polling in certain cases also adversely
affects performance of already overloaded host systems, both VTAM and
VM.

      A new API has been created.  The new API makes a screen capture
of what is displayed befo...