Browse Prior Art Database

Sliding Polling Timeout Technique

IP.com Disclosure Number: IPCOM000050613D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 25K

Publishing Venue

IBM

Related People

Dayan, RA: AUTHOR [+2]

Abstract

In a communicating shared resource environment, a problem arises when several of the attaching systems are offline. If the shared resource controller also has the responsibility for initiating communications as a primary to multiple secondary systems, non-responding systems may seriously impact overall resource performance.

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Sliding Polling Timeout Technique

In a communicating shared resource environment, a problem arises when several of the attaching systems are offline. If the shared resource controller also has the responsibility for initiating communications as a primary to multiple secondary systems, non-responding systems may seriously impact overall resource performance.

Presented herein is an algorithm that can be used to reduce the effect of offline secondary systems upon the performance and throughput of all the operating systems in the environment.

Normally the primary system polls each secondary system individually but in a rotating sequence. This process is continuous in most cases, as follows. System 1 --> System 2 --> System 3 --> System 4. The problem that arises is that performance and throughput of all operating systems in the shared environment are affected when one or more secondary systems are not responding. Polling the offline system(s) continuously wastes a lot of time.

In order to improve performance and throughput of the systems, the polling control program should first drop the secondary system upon detection of it being offline. Based on the previous example, if System 2 was polled and no response followed, the new poll list would be as follows: System 2

System 1 -------------> System 3 --> System 4
Next, a time interval should be established in order to attempt to bring the offline secondary back to an online condition. When the time interval expires, the polling program should reinstate the secondary station to the poll list and should poll the offline secondary to see if it is ready to become active again. If active, its position should be reinstated in the poll list. If still inactive, it should be removed from the poll list once again.

The above-described situation is only a special case of the overall solution. It is the simple case of only one secondary being offline. However, if this simple case was extended to multiple offline secon...