Browse Prior Art Database

Adjusting Communication Polling Rates Based On Communication Line Utilization

IP.com Disclosure Number: IPCOM000119575D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Kiel, HG: AUTHOR [+2]

Abstract

A Work Station Controller (WSC) provides attachment of multiple work stations to a computer system. The WSC communicates with work stations using some type of communication protocol. In some protocols, the WSC polls attached work stations at some rate, checking for new status. This article describes how polling rates can be dynamically adjusted based on the utilization of the communication line or utilization of the driver/receiver hardware which drives the communication line. Work stations can include dependent displays, programmable work stations, and printers. A typical local WSC with attached work stations is shown in the figure. This article also applies to remote WSCs (which attach to the host processor via communication line instead of system bus).

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This is the abbreviated version, containing approximately 52% of the total text.

Adjusting Communication Polling Rates Based On Communication Line
Utilization

      A Work Station Controller (WSC) provides attachment of
multiple work stations to a computer system.  The WSC communicates
with work stations using some type of communication protocol.  In
some protocols, the WSC polls attached work stations at some rate,
checking for new status.  This article describes how polling rates
can be dynamically adjusted based on the utilization of the
communication line or utilization of the driver/receiver hardware
which drives the communication line.  Work stations can include
dependent displays, programmable work stations, and printers.  A
typical local WSC with attached work stations is shown in the figure.
This article also applies to remote WSCs (which attach to the host
processor via communication line instead of system bus).

      A typical WSC could poll each work station checking for new
status in one of two modes:
-  Polling for keystrokes or other new status
-  Polling for completion of a previously sent command: polling
continues until the work station indicates processing of the command
is complete.

      This article describes how communication line utilization or
driver/receiver utilization can be used to adjust polling rates.  For
example, utilization can be calculated using a sampling technique.
Assuming the WSC has a timer available, periodically, a sample count
is incremented and the state of the driver/receiver hardware is
checked.  If the hardware is busy, a busy count is also incremented.
After a statistically significant number of samples have been taken,
utilization is calculated for this period and polling rates adjusted.
The percentage of utilization is obtained by dividing the busy count
by the sample count.  After the utilization is calculated, both the
sample count and busy count are reset.

      In general, if the utilization is low, polling is...