Browse Prior Art Database

Detection of Element/System Timeouts

IP.com Disclosure Number: IPCOM000103164D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 44K

Publishing Venue

IBM

Related People

Brey, TM: AUTHOR [+6]

Abstract

A central hardware "hang timer" is described which sends pulses to all elements of the system. The elements establish an appropriate time interval for these pulses, along with a system hierarchy of detection time intervals, for detecting when an element of the system (or the system) has exceeded the normal response time for a transaction.

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This is the abbreviated version, containing approximately 81% of the total text.

Detection of Element/System Timeouts

      A central hardware "hang timer" is described which sends pulses
to all elements of the system.  The elements establish an appropriate
time interval for these pulses, along with a system hierarchy of
detection time intervals, for detecting when an element of the system
(or the system) has exceeded the normal response time for a
transaction.

      There are two triggers to identify a "state" used in detecting
a hang condition.  When an event which requires a response occurs, a
trigger is set to indicate a response is required.  If a timer pulse
occurs before the response is received, a second trigger is set to
indicate the event is "ARMED" for a hang detection.  Using these
triggers, a hang condition is detected if another time pulse is
received before the expected response is received.

      System circuits define how many timer pulses an element should
wait.  In an Input/Output design described below, the number of
"TIMER TICKS" are in relation to the distance from the source of data
to the recipient of the data:
 CHANNEL  -  CHANNEL HANDLER  -  I/O PROCESSOR  -  STORAGE
   8     -         4         -        2        -     1
 RECIPIENT                                          SOURCE

      The timer pulses are disabled under certain environmental
conditions so as not to cause false detection. Examples are when the
source...