《BS-6238-1982.pdf》由会员分享,可在线阅读,更多相关《BS-6238-1982.pdf(18页珍藏版)》请在三一文库上搜索。
1、BRITISH STANDARD BS 6238:1982 Code of practice for Performance monitoring of computer-based systems UDC 681.3.02.001.42:651.012.14 Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 10:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6238:1982 This British Standard, having been prepared under
2、 the direction of the Office and Information Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 March 1982 BSI 03-1999 The following BSI references relate to the work on this standard: Committee reference OIS/15 Draft for comment 81/60468 DC ISBN 0
3、 580 12658 7 Cooperating organizations The Office and Information Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: British Computer Society Ltd.*HM Customs and Excise British Paper and Board Industry Her Majestys Stationer
4、y Office Federation (PIF)Institute of Administrative Management British Telecom*Institute of Chartered Secretaries and Business Equipment Trade Association*Administrators Central Computer and Telecommunications Institute of Cost and Management AgencyAccountants Committee of London Clearing Bankers o
5、n Institute of Data Processing Management Behalf of the Committee of ScottishInstitute of Purchasing and Supply Clearing Bankers, Co-operative Bank,Institution of Electrical Engineers Central Trustee Savings Bank and Inter-university Committee on Computing Yorkshire BankLocal Authorities Management
6、Services and Computing Services Association*Computer Committee* Department of Industry, Computers SystemsLondon Transport Executive and ElectronicsMinistry of Defence* Department of Industry, National PhysicalNational Computer Users Forum Laboratory*National Computing Centre Ltd.* Drawing Office Mat
7、erial Manufacturers andNational Research Development Corporation Dealers AssociationOffice Machines and Equipment Federation Electricity Supply Industry in England andSimplification of International Trade Wales*Procedures Board The organizations marked with an asterisk in the above list, together wi
8、th the following, were directly represented on the Technical Committee entrusted with the preparation of this British Standard: Association of Computer Units in CollegesElectronic Engineering Association of Higher Education (ACUCHE) Amendments issued since publication Amd. No.Date of issueComments L
9、icensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 10:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6238:1982 BSI 03-1999i Contents Page Cooperating organizationsInside front cover Forewordii Section 1. General 1Scope1 2References1 3Definitions1 Section 2. Key aspects of the system being mo
10、nitored 4General1 5Applications software1 6Operating and support software2 7Hardware configuration3 8Hardware ageing3 9System inputs4 10System usage5 11Effects of other systems6 Section 3. Monitoring techniques 12General7 13Use of routine records7 14Hardware monitors8 15Software monitors8 16In servi
11、ce testing9 17System audit10 18User surveys10 Section 4. Performance monitoring reporting 19General11 20Performance criteria11 21Evaluation of performance measurement data11 22Performance reporting12 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 10:
12、09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6238:1982 ii BSI 03-1999 Foreword This code of practice is concerned with monitoring the performance of a computer-based system in service. It is complementary to BS 5887 and is relevant to the same range of systems and environments. BS 5887 recomm
13、ends that “systems that are particularly important to the user and have one or more critical qualities should be monitored while in use” in order to ensure that adequate standards of performance are maintained. In this context it is necessary to: a) appreciate what influences may affect the performa
14、nce of a system in service; b) be aware of the range of monitoring techniques which may be employed to detect the effect of these influences. This code provides a basis upon which organizations can develop performance monitoring procedures appropriate to their needs. The extent to which these recomm
15、endations are applied will vary according to the relative complexity of each system and its importance to the organization. It is important to recognize that the impact of changes on the performance of the system can differ according to whether these changes are: a) identified in sufficient time for
16、 their effects to be evaluated; b) unpredicted and gradual so that there is a risk of their effects going unnoticed until they reach a critical point; c) unpredicted and sudden with an immediate effect on system performance. It follows from this that every effort should be made to impose adequate co
17、ntrols on change in order that serious effects upon levels of performance can be anticipated and appropriate action taken. Each organization should examine each of its systems to establish what aspects are particularly critical to their requirements. Section 2 of this code is intended to assist orga
18、nizations to conduct this examination by identifying elements of change to those aspects that can affect the performance of a system. There are some changes that may affect more than one of the key aspects in section 2. These have been repeated in the text of the code, where necessary, for the sake
19、of clarity. Having established which elements are considered to be important, the organization should then establish which monitoring techniques will provide the information necessary to determine the degree to which these elements may affect the performance of the system. Section 3 is intended to a
20、ssist organizations to identify the techniques which can be applied most effectively to their particular hardware and software configurations. The most cost-justifiable of these effective techniques can then be applied. It is essential to assess each system correctly so that the monitoring procedure
21、s that are developed are adequate without exceeding the bounds of cost-justified necessity. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with it does not confer immunity
22、 from relevant statutory and legal requirements. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This wil
23、l be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 10:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6238:1982 BSI 03-19991 Section 1. General 1 Scope This code of practice applies to all computer-based systems. It comprises f
24、our sections. Section 1 comprises preliminary clauses. Section 2 gives guidance in carrying out a detailed examination of the system that is to be monitored. It identifies key aspects of the system, its usage and other systems that share the same operating environment. Guidelines and check lists are
25、 provided for each of these aspects to assist the user in identifying elements of change that can affect performance. Section 3 identifies a variety of monitoring techniques that may be used to measure these changes in performance. Section 4 gives guidance on the documentation of performance monitor
26、ing information. This code gives guidance to enable organizations to: a) assure the continuing quality of a computer-based system in service; b) develop and apply appropriate monitoring techniques; c) obtain early diagnosis of changes in the behaviour of the system; d) detect faults so that action c
27、an be taken to avoid fault propagation. This code assumes that the system: a) was adequately tested in accordance with BS 5887 and documented in accordance with BS 5515; b) performed as required under normal operating conditions; c) was initially schedulable within the constraints imposed by other s
28、ystems and manufacturers design. This code also assumes that, in service: a) the system runs under effective configuration management; b) documentation is maintained. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Definitions For the p
29、urposes of this British Standard the definitions given in BS 3527 apply. Section 2. Key aspects of the system being monitored 4 General This section gives guidance that is designed to assist the user to make a detailed examination of the system being monitored for all the likely causes of a change i
30、n performance. It also indicates ways in which changes to other systems sharing the same resources may affect the performance of the system being monitored. 5 Applications software 5.1 General. Some elements of change may have been anticipated during the design of the system but serious effects can
31、arise from changes that occur, but which were not visualized in the original specification. 5.2 Elements of change. Among the elements of change that should be examined, the user should note that: a) standards of accuracy can affect processing times; b) security controls can extend input and output
32、duration; c) validation checks can extend input and output duration; d) changes in coding of data can affect input and output times and storage capacity required; e) changes in code structures can affect input and output times and storage capacity required; f) changes in the structure of the data ba
33、se and files can affect input and output times and storage capacity required; g) changes in input method/documents can increase input times; h) changes in output method/documents can increase output times; i) changes in parameter values can change processing times; j) changes to algorithms or formul
34、ae could change processing times; k) some changes may not be reflected in the procedures; l) some changes may not be reflected in the documentation. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 10:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6238:1982 2 BSI 03-1999 6 Operating and s
35、upport software 6.1 Introduction. Changes to the operating and support software and system can have a considerable influence on the efficiency and behaviour of a system. Such changes are quite usual for various reasons (e.g. correction of faults or the improvement of facilities) but a careful examin
36、ation of their implications should be made to ensure that no harmful side effects will occur. 6.2 Elements of change 6.2.1 Operating software. Operating software includes all the system facilities used in the course of running application programs. The main consideration is that an alteration to a s
37、ystem facility may affect some or all application programs, or modules, and it may not be practicable or desirable to cross-reference facilities with applications. Hence changes cannot necessarily be guaranteed to have no side effects and each one should be treated on its merits. The main system fac
38、ilities that come under this consideration are: a) system library, holding commonly used modules; b) file handling system (changes here almost certainly affect all application programs); c) job control language (new or added commands or formats); d) input/output; e) scheduling. (Changes to the prior
39、ity strategy will affect run-times, elapsed times or even what time of day or night an application will be run. These in turn will affect the run-time costs.) 6.2.2 Support software 6.2.2.1 General. This software includes all the system facilities used in the course of program preparation. The undes
40、irable result of changes in this area is the necessity for programmer retraining and the possible reduction in software quality and throughput until the changes are fully understood. 6.2.2.2 Language translators (compilers). Special consideration should be given to this facility. Changes in this are
41、a may have a very significant effect on application systems performance and should be carefully vetted as they may not always be apparent. Generally, changes will be manifested as version updates or the same language from a different supplier (probably giving faster run-time code, or better store ut
42、ilization, or just improved facilities). Even if a system has been extensively acceptance tested, there remains a need to understand that it is inherently impossible to obtain 100 % assurance that errors have been eliminated or all implications fully appreciated. Some of the more obvious features th
43、at may cause difficulty on an otherwise identical translator are syntax, semantics, reserved words and keywords, translator directives and linking. Some of the less obvious features that should be considered are as follows. a) Arithmetic. Although these problems should be resolved during acceptance
44、testing of the new translator, explicit checks should be made on the following points to ensure conformity with previous software: 1) truncation and rounding; 2) the result and remainder from the division algorithm; 3) equality tests for floating or mixed arithmetic; 4) overflow limits should not be
45、 less than previous limits. b) Expressions. This feature is a similar problem to a) and the following points should be checked: 1) order of evaluation should be identical; 2) mixed “type” conversion should give identical results; 3) intermediate state limits should not be less than previous limits.
46、c) Procedures and functions. The following points should be checked: 1) order of parameter evaluation should be the same; 2) the parameter mechanism should behave in the same way for the same cases (by reference, value etc.). This behaviour is particularly important for default cases. d) Optimizatio
47、n. A different optimization method can give different results for some application programs. e) Error handling. Changes can cause some temporary misinterpretation. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 10:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6238:1982 BSI 03-19993 6.2
48、.2.3 Other support software. This category includes facilities such as: a) time sharing command structure; b) debugging tools; c) editor; d) linker. Changes to the linker can also interact with the system library, which is considered under operating software (see 6.2.1). 6.2.3 Software reconfigurati
49、on. Although there may be no changes to the products that form the operating and supporting software, they may be reconfigured in such a way as to affect the performance of a system. Some of the aspects that need to be considered in these circumstances are: a) mapping of software on to different types and speeds of media/devices; b) minimizing the possible overheads of paging; c) change in program loading format and method; d) regeneration of system software; e) selection of new running modes such as choice of long error messages or full listings; f) change in normal residence
链接地址:https://www.31doc.com/p-3772164.html