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Browse Prior Art Database

Threshold Policy for Minimum Response Time Based Transaction Routing Strategy

IP.com Disclosure Number: IPCOM000103717D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 93K

Publishing Venue

IBM

Related People

Lee, YH: AUTHOR [+2]

Abstract

A threshold policy is disclosed to improve the robustness of the minimum response time (MRT)-based strategy. By imposing a threshold on load unbalancing before MRT is applied, the system performance can be improved. More significantly, the strategy does relatively well even if inaccurate transactions characteristics are used.

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

Threshold Policy for Minimum Response Time Based Transaction Routing Strategy

       A threshold policy is disclosed to improve the robustness
of the minimum response time (MRT)-based strategy.  By imposing a
threshold on load unbalancing before MRT is applied, the system
performance can be improved.  More significantly, the strategy does
relatively well even if inaccurate transactions characteristics are
used.

      Let there be K transaction classes in the system and let txk
denote a class K transaction, k = 1,...,K.  For the k-th class,
transactions arrive according to a time-invariant Poisson process
with rate gk.  The mean processing service demands of an application
processing segment and a database request of txk are ak and bk,
respectively.  Both ak and bk can be estimated by measuring the path
lengths of application processing and database request.  For each
database request issued by txk, we assume that an I/O device will be
accessed with a fixed probability pk, and the service time of each
I/O access is exponentially distributed with mean dk.  When the
executive of an application processing segment is completed,
transaction txk may issue a database request to the database
partition DBi with probability pki, or may terminate with probability
pKO.  The matrix [pki] shows the distribution of database calls
issued by txk and is referred to as the reference locality
distribution.  For a given transaction txk, we call the processing
system Pi its preferred system if pki is the maximum of pkjj =
1,2,...,N.

      When a transaction being executed at Pi issue a database
request to DBj, where i / j, the database call must be shipped from
processing system Pi to Pj.  After the request gets processed, the
result will be sent back.  This is called a remote database call in
which both Pi and Pj have to perform sending and receiving services.
The service demands of initiating a remote database call and of
receiving the results of the call are referred to as communications
overhead and are assumed to be exponentially distributed with mean c.

      As routing transactions to a non-preferred system increase the
total system load due to remote call overhead, threshold strategy
intends to route transactions to a non-preferred system only when a
sizeable gain in re...