Schoute, Albert Louis

English

ARTS repository - University of Groningen

   University of GroningenModelling of virtual memory computer systems with multiple classes of processesSchoute, Albert LouisIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:1978Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Schoute, A. L. (1978). Modelling of virtual memory computer systems with multiple classes of processes.s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 08-06-2022]fIPreface and SummarYThe  impac t  o f  many  o f  t he  des ign  dec i s i ons  and  schedu l i ng  ru l es  i npu rpose  i n t c rac t i ve  compu te r  sYSLem i s  o fLen  sca rce l y  knowr :  ow lngcomplexi ty of  the system i tsel f  and of  the user demands-Ana l ys i s  and  mode l l i ng  o f  compuLe r  sys tems  has  Lhe re fo re  deve lopedimpo rLanL  sub jecL  i n  compuce r  sc i ence .to  thein to  anGood interact ive serv ice to many users re l ies on a number of  technicaldevelopments which have faci l i tated the preempt ion and real locat ion of  themain computer resources,  such that  serv ice can be given at  a rather equalpace.  This has the obvious advantage that  smal f  demands are not  delayed byLarge deman<ls,  so ens;ur ing aulomat ical ly  that  fa i r  serv ice is  rnainta ined.Another consequence of  the div is ion of  the computer resourceS amongstmany  use rs  i s  t ha t  t he  u t i l i sa t l on  o f  t hese  resou rces  i s  no t  so  r nuch  d i c t a tedby the speci f ic  character is t ics of  the user dernands but  rnore by the al loca-t i on  po l i c y  o f  Lhe  sys tem i l se l f  and  by  t he  gLoba l  cha rac te r i s t j c s  o f  t hework l oad  p resen ted  by  t he  use rs .Th i s  may  exp la . i n  t he  re l a t i ve  success  o f  t he  app l i cac i on  o f  s imp le  queue ingne two rk  mode l s  as  a  r ep resencaL ion  o f  t he  dynam ic  execuL ion  o f  usc r  p rog ramswhlch are s imul taneously in a state of  execut ion (mul t i -prograrnrning) .One  o f  t he  t echn i ca . I  deve lopmenLs  wh i ch  has  imp roved  i n t e rac t i ve  sysLems  i st he  v i r Lua l  memo . r y  t echn ique  (o f t en  imp lemen ted  by  means  o f  pag ing ) ,  wh i chmakes  Lhe  dynam ic  use  o f  ma in  memory  cons ide rab l y  s impLe r .  r n  r espec t  o f  t heuse of  main memory,  i t  a lso seems desirable to d iv ide i t  in  a s imple mannerbe tween  use r  p rog ram wh i ch  requ i r e  Se rv i ce .  Howeve r ,  t he  a l l oca t i on  o f  ma lnmemory appears to be a rather cr i t ical  aspect '  on the one hand because as , t f f i c i enL  a l l oca t i on  (acco rd i ng  t o  t he  i nd i v i dua l  needs )  i s  a  p re requ j s i Lcfor  sat is factory execut ion and on the other hand because reaf focat ion impl iesun loao ing  and  re l oad ing  o f  pa r t s  o f  ma in  memory  and  Lh j s  causes  p rocess jngoverhead and deIaYS.The memory al locat ion may be considered as a fLood-gate which plays ani m p o r t a n t  r o l e  w i L h  r e s p e c t t  L o  a  g o o d  i n t e r a c L i v e  s e r v i c e  a n d  a  g o o d  u L i l i -sa t i on  o f  t he  cen t ra l  p rocess ing  capac i t y .^ - - i n n  n f  m : i n  m e m ^ r \ /  i q  r h o  m n c f  i m r , ^ r f ^ n f  ^ h i o . t i v a  ^ f  ^l r t e  u P L l n r a r  o r f g u a L l -  r r u r L  f r r l u rc l d s s l f i c a t j o n  o f  p r o c e s s e s ,  a c c o r o j n g  t o  t h e i r  e x p e c t e d  d e m a n d s .  A s  i nt h e  E d i n b u r g h  M u l t i  A c c e s s  S y s t e m  ( E M A S )  [ W h i l  f i e l d  a n d  W i g h L  1 9 7 ] ,S n e l n e s s  e t  a l .  1 9 7 1 1 ,  w h i c h  h a s  L o  a  l a r g e  e x t e n c  b e e n  u s e d  a s  t h e  o b j c c to f  Lh j s  s t udy ,  t he  expec ta t i ons  cou , l d  be  based  on  t he  demands  i n  t ne  recenLp a s c .l r r  L h - i s  t h e s i s  w e  c o n s i d e r  m o d e l l l n g  a s p e c t s  o f  v i r t u a f  m e m o r y  s y s t e m s  w i L hm u f t i p l e  c l a s s e s  o . f  p r o c e s s e s .  T h e  e x i s t e n c e  o f  t h e s e  d i f f e r e n t  c l a s s e sc o u l d  b e  c o n s j d e r e d  a s  b e i n g  i n  s o m e  w a y  r e p r e s e n L a l i v e  o f  t h e  d i f f e r e n tI  r z n o q  n F  d p m ^ n d c  n a n o r : f a d  h r r  r r q a r cB e c a u s e  o f  m a l i y  p r a c t i c a l  a s p e c t s  ( s u c h  a s  I i m i t a L i o n s  d u e  L o  L h e  f j n i t e n e s so f  memory ) ,  queue ing  ne two rk  mode fs  a re  e i Lhe r  Loo  comp l i ca ted  t o  be  so l vedo r  f o rm  on l y  a  pa r t i aL  r ep resen taL ion  o f  Lhe  accua l  se r v j c i nq .  A  q rea t -  dea lo f  ma themaL i ca l  ana l ys i s  i s  t he re fo re  be ing  done  i n  r e l a t i on  Lo  t he  pe r -f o rmance  ana l ys i s  o f  compuLe r  sys tems .  A  gene ra -L I y  used  (and  i n  many  casesi r e r r i t a h i e )  w r r t  n f  q o l r r i n o  o t r e r r e i n a  m n d e l q  f n r  c n m n r r l a r  q \ / a t o m c  i q  h r ;  m o r n <J v 4  v  + r , Y  r l  -  L !  r ' r Jo f  a  h i e ra r ch i ca l  d , ecomcos i t i on .C o u r t o i s  l l 9 l 7 )  c o n s i d e r s  i n  h i s  b o o k  o n  d e c o m p o s a b i l  i t y  t h e  j u s t i f i c a t i o no f  t h i s  Ly?e  o f  so l r , t i on  me thod  and  t he  poss ib l e  app l i ca t j ons  t o  compu te rq \ / q l  e m  m o d c l  q  T n  j -  h i  q  f  h p c i  c  r l e c a m n n c : h i  l  i t \ 7  r c n a . l - c  : r a  l r o ^ f  a d  l - \ \ ,v ! ! v n r r v J s ! !d i f f e ren t  me thods .W e  g i v e  i n  C h a p t e r  1  a  r e p r e s e n L a L j o n  f o r  t h e  s c a t j o n a r y  s o l u t i o n  o f  f i n i L es t a L e  M a r k o v  p r o c e s s u s ,  w h i c h  m a k e s  u s e  o f  g r a p h s .  l ' h i s  r e p r e s e n t a t i o n ,ca l f ed  t he  t r ee - f o r rn  so lu t i on ,  i s  used  t o  show  the  essen t l a l  cha rac te r i s t i c so f  s y s t e m s  w h i c h  h a v e  a  s i m p l e  p r o d u c t - f o r m  e x p r e s s i o n  a s  s o l u L i o n .  I n  t h j sf r amework  ques t j ons  o f  decomposab i l i L y  and  sLaLe  agg rega t i on  become  moreI  r a a q n ^ r F n l  : n d  m : - r  - '  o c 1 - i m : l  i n a  t h a  m o : c r r r o  n f  ^ o c n m n n -u r / u  r r u /  r r E w  w d y s  u r  - _ _ _  u L  u s u u i i l I , u -q : h i l i l \ /  f e o - f i ^ n  . 1  / \D r . / r  r . f - f n r m  n r r a r r a i r o  n e r w o r k q  r r o  i n  ( - h a n i  a r  )  r o 1  ^ r a d  f ^  c n o . i i l  / h r ' l > n n o r lY s !  q ! t / , Y  u r r u y u !  \ , u r q r . u L umuf t i - d imens iona l  b i r t h  and  dea th  p rocesses .D i f f e ren t  l eve l s  o . [  v i r t ua l  memory  sys tem mode l l i ng  a re  t r eaLed  i n  ChapLe rsI  r o  5  T n  a h ^ n f  e r  I  f  h n  l - ' r c i  -  ^ n a r : f  i  ^ n  6 f  \ / i  r f  r r : l  m F m ^ r r r  < r r q f  a m c  u l i  t  hp a g i n q  i s  s k e L c h e d  a n d  b a s i c  a s s u m p t i o n s  c o n c e r n i n g  p r o c e s s  b e h a v i o u r  a r econs ide red .  I t  i s  shown  Lha t  f o r  adapL i ve  memory  a l l oca t i on  po l i c i es( e . 9 .  w o r k i n g - s e l  a l g o r i t h m s )  L h e  s i n g l e - - I i f e L i m e - f u n c L j o n  m o d e . I s  a r e  n o ta i o f l r r A f F  a q  d c q n r i n j - i n n  n f  f h e  n : a i n n  h o h e r r i n r r r  p A f f i n d  h e h : r r i - r l r  m : \ z  l - ' aI  r  I  u Y  u r  r l u l  p !c o n s i d e r e d  w i t h i n  t h e  c o n t e x t  o f  a  c l a s s i f l c a t i o n  s y s L e m  o f  p r o c e s s e s .  T h ee f f ec t s  o f  a  se l ec t i ve  a l l oca t . i on  sys tem,  such  as  t . haL  imp lemenLed  i n  EMAS,a r e  a n a l y s e d  i n  s e c l i o n s  3 . 5  L o  J . 7 .r )  . L . - + a r  L . , 6  ^ ^ - - i d ^ r  l h e  r r q o  o f  o r r c r ) A i n o  n e l  w o r k  m o d e l  q .  T h e  r e S U f t S  O fq u e u e j n g  n e L w o r k  m o d e f s  w i t h  m u l t i p l " e  c f a s s e s  o f  p r o c e s s e s  I B a s k e t t  e t  a l1 9 7 5 ]  a r e  p r e s e n l c d  w i t h i n  L h e  c o n L e x t  o f  C h a p t e r  2 .W e  j n v e s t i g a t e  h o w  m o r e  p r e c i s e  m o d e l l i n g  w i L h  r e s p e c t  t o  p r i o r i t y  s e r v i c eo f  Lhe  CPU and  bu l k  se r v i ce  by  Lhe  pag jng  d rum may  be  ach ieveJ .A t  t h e  g l o b a l  f e v e l  t h e  m e m o r y  a d m i s s i o n  i s  a n  i m p o r t a n t . [ a c L o r ,  e s p e c i a l f ywhen  d i f f e ren t  c l asses  o f  p rocesses  a re  cons ide red .We  g i ve  i n  Chap te r  5  an  accoun t  o f  t he  ex ten t  t . o  wh i ch  p roduc t - f o rm  mode l sc a n  b e  u s e d  i n  t h j s  a r e a .  M e m o r y  a l l o c a t i o n  r e q u i r e m e n t s  o f  d i f f e r e n t  s i z e sm a k e  a  r e a l  i , s t i c  m o d e l  I i n g  o f  t h e  a d m j s s t o n  p r o c e s s  ( b y  a n a f y t i c a l  m e a n s )e x L r e m e r y  d i f f j . c u l t .  E i t h e r  c r u d e  a p p r o x j - m a L i o n s  m u s t  b e  m a d e  o r  n u m e r i c a rmethods have to be used.some resul ts f rom exper iments on EMAS are given in the last  chapter  ancl  anumber  o f  mode l l i ng  exampLes  a re  wo rked  ou t .

Modelling of virtual memory computer systems with multiple classes of processes

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Modelling of virtual memory computer systems with multiple classes of processes

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