Formal Models of Operating System Kernels phần 6 pptx

... most significant aspect of this chapter’s model is that it acts as an existence proof. It is possible to define a formal model of an operating system kernel and to prove some of its properties. In ... of the current kernel. 5.2 Requirements The requirement is to model an operating system kernel that is based upon the exchange of messages between processes. The kernel should...

Ngày tải lên: 23/07/2014, 23:20

... 252 PagingDiskProcess INIT 263 OnPageRequest 266 PageIsOnDisk 265 RemoveProcessFromPagingDisk 266 RetrievePageFromDisk 265 StorePageOnDisk 265 ProcessCreation: createASystemProcess 194 createAUserProcess ... 166 MarkAsInStore 166 MarkAsSwappedOut 166 NextProcessToSwapIn 172 ProcessStoreSize 168 ReadyProcessChildren 169 RemoveProcessStoreInfo 168 SetProcessStartResidencyTime 167 S...

Ngày tải lên: 23/07/2014, 23:20

... counter are: BIT == {0, 1} N 2 56 == 0 255 (N 2 56 is just the naturals 0 2 16 − 1—i.e., a 16- bit unsigned.) The computation of the counter value forms part of the predicate of schema ComputeHitCounts. ... N pgallocstart =0 The value of 0 is completely arbitrary, as is now explained. Some systems map a virtual copy of the operating system onto the vir- tual address space o...

Ngày tải lên: 23/07/2014, 23:20

... comprising the system- call library all send and receive messages. Therefore, the rest of the proof must be in terms of the properties of the message-passing subsystem. The message-passing subsystem is ... of sharedpages(p)(sg), for some p and sg. Proof. Similar to the previous proof. ✷ Proposition 134. IsLockedPage iff lpno? is a locked page; that is, iff lpno? is an element of lock...

Ngày tải lên: 23/07/2014, 23:20

... • msgmgr.RcvMessage[/src?,/dest?, m/m!] ∧ DoDiskSwap) 5 .6 Kernel Interface Some readers will have been wondering why a proper system interface has not been defined in any of the models so far. The first kernel merits ... message contains the identifier of the sending process. It also contains two natural numbers (elements of N). They denote the size of the data area and the size o...

Ngày tải lên: 23/07/2014, 23:20

... to determine all the children of a parent process. 4.8 General Results This final section contains the proof of a number of propositions that deal with properties of the kernel. The propositions ... an idea of some of the other things that might need to be handled during termination). If a process is on disk when it is terminated (say, because of system ter- mination or because...

Ngày tải lên: 23/07/2014, 23:20

... descendant of the ancestor of the process just blocked. Proof. This requires the proof of the following lemma. Lemma 16. For any process, p, BlockProcessChildren implies that there are no children of ... closure of the childof relation; the complete set of descendants of a given process are represented by childof + (|{p?}|) for any process identifier p?. In BlockProcessChildren,...

Ngày tải lên: 23/07/2014, 23:20

... • parentof (p 1 , p?)) RemoveProcessFromParent ∆(parentof ) parent?, child?:APREF parentof  = parentof \{(parent?, child?)} ParentOfProcess p?:APREF parent!:APREF (∃ p 1 : APREF • parentof (p 1 , ... priority of process, p. If p is an element of q, then MakeUnready[p/pid?] implies that p is not an element of q  . Proof. There are two cases to consider: Case 1. Process p is the head o...

Ngày tải lên: 23/07/2014, 23:20

... performed, the inclusion of IdleProcRef and the ex- clusion of NullProcRef are of some importance. They determine the range of possible values for the domains of the components of process descriptors. ... execution of a piece of code. They are used as a kind of low- level mutual exclusion mechanism. 4.3 Common Structures 101 Proof. By a previous Lemma (Lemma 5), | scnt| =#el...

Ngày tải lên: 23/07/2014, 23:20

... 228 5 .6 KernelInterface 231 6 Virtual Storage 239 6. 1 Introduction 239 6. 2 Outline 239 6. 3 VirtualStorage 240 6. 3.1 The Paging Disk Process 263 6. 3.2 Placement:Demand Paging andLRU 267 6. 3.3 ... the upper layers of an operating system. OS Kit is a software kit, not a formal specification or modelling tool. Iain D. Craig Formal Models of Operating System Kernel...

Ngày tải lên: 23/07/2014, 23:20