Browse Prior Art Database

Method for Measuring CPU Load

IP.com Disclosure Number: IPCOM000077991D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Milewski, A: AUTHOR [+2]

Abstract

This is a simple method for measuring the average load of a CPU in a real-time system processing random events, which can be queued before handling.

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Method for Measuring CPU Load

This is a simple method for measuring the average load of a CPU in a real- time system processing random events, which can be queued before handling.

This method can be used in particular, in a telephone exchange system including a computer. Such a system processes programs of substantially constant length which permits, in particular, detection of "events", and programs for handling such events. When an event has been detected by a program of the first type, it is stored in a queue; during the interval between the programs of the first category, the queue is read and handled.

The proposed method uses two counters C1 and C2. At regular intervals (e.g. every 3 seconds), the contents of the queue is tested. If the queue is empty, counter C1 is incremented by 1: otherwise, C2 is incremented by 1. After a statistically reasonable number of samples have been taken (e.g. every 15 minutes), the ratio C2 over C1 + C2 is calculated. This ratio represents the percentage of the time taken by the handling of the events, relative to the time left free of the programs of the first type.

This method is less rigorous than more complicated methods based on clocking measurements, but it is sufficiently accurate in most cases.

Furthermore, it can be introduced in a system without modifying the existing program.

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