From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f43e6,5ac12f5a60b1bfe X-Google-Attributes: gidf43e6,public X-Google-Thread: 103376,5ac12f5a60b1bfe X-Google-Attributes: gid103376,public From: john@assen.demon.co.uk (John McCabe) Subject: Re: Ariane 5 - not an exception? Date: 1996/08/03 Message-ID: <839064766.1301.0@assen.demon.co.uk>#1/1 X-Deja-AN: 171777779 x-nntp-posting-host: assen.demon.co.uk references: <4tb8vv$bna@zeus.orl.mmc.com> <838637917snz@nezumi.demon.co.uk> <838749361.12233.0@assen.demon.co.uk> <32001F86.49D1@ee.ubc.ca> newsgroups: comp.software-eng,comp.lang.ada Date: 1996-08-03T00:00:00+00:00 List-Id: Greg Bond wrote: >John McCabe wrote: >> snip... >> >> I find it difficult to understand why the design and development team >> even considered maintaining the CPU load at <80% for this particular >> case. If they requested a waiver on that margin and were refused then >> obviously their prime contractor (or whatever) is to blame, but there >> is no way that CPU loadings with margins of 20% should have been >> enforced at the risk of mission failure. >> >> <..snip..> >Correct me if I'm wrong, but doesn't a lower CPU utilization help ensure >that hard deadlines will be met in exceptional copmutational >circumstances (thereby helping to prevent mission failure....)? Yes, that is also true, but if adequate analysis and testing of real-life situations take place, then this requirement should be waived. On my current program we have performed these analyses to discover exactly what can happen and when, and this takes into account things that may happen but aren't supposed to. We can therefore ensure (withiin reason) that the timing requirements we meet are realistic but do not necessarily meet a (in our case) 30% margin. Best Regards John McCabe