[CST-2] Comp. Sys. Modelling

[Chris Applegate]

CSM - 2000P9Q7

Has anyone done this. If so...I have a couple of queries...

Second part - can we give a numerical value to this? Since the bounds of
a balanced machine depend on utility, which depends the number of
customers, then I can only give a formula answer of 10N/(3+N) &
40N/(3+N) as the bounds...

Third part - first of all, I'm assuming the formula on the paper is
wrong and it's actually X(N) = N/(N+K-1) x 1/Di like the notes, not with
the plus sign like on the paper... - what value of demand do we use to
get the 'expected value'. If it's Dmax (i.e. 0.1 s for Disk 2 from part
(2)) which means 7 users in the system at any one time. Or alternatively
Dav (which I get as 0.05375 s from averaging all the D values) I get
1.81. Which is the right one to pick? I assumed Dav but then it's later
given in the notes as an 'optimistic' bound, and I suppose I have to
consider the system bottleneck...or I might be utterly wrong...

Oh, and does anyone know where to get decent coffee this time of
night...I'm all out, and the usual places are shut. ¦-O

Cheerio,

Chris
do something lastminute.work

Chris Applegate
Room X6, Corpus Christi College, Cambridge, CB2 1RH
chris@qwghlm.co.uk / www.qwghlm.co.uk / [Redacted by SRCF sysadmins on request]
ICQ 41706821          PGP key available on request