Process Manager Overview

Transcription

1 Process Management

2 Process Manager Overview Program Process Abstract Computing Environment Device Manager File Manager Memory Manager Deadlock Protection Synchronization Scheduler Process Description Resource Resource Manager Resource Manager Manager Devices Memory CPU Other H/W

3 Process Management Representing the essential characteristics of a process -- the process descriptor What things can be referenced -- the address space Allocating resources Creating/destroying processes Scheduling the CPU (Chapter 7) Synchronization mechanisms (Chapters 8-9) Deadlock (Chapter 10)

4 Process Descriptor OS creates process abstraction Descriptor is data structure for the process Register values Logical state Type & location of resources it holds List of resources it needs Security keys etc. (see Table 6.1 and the source code of your favorite OS)

5 User Supervisor Libraries NT Organization T Process T Subsystem NT Kernel Hardware Abstraction Layer T NT Executive T Process Subsystem Process T T T T T Subsystem I/O Subsystem Processor(s) Main Memory Devices

6 NT Process Descriptor User Space Supervisor Space NT Executive EPROCESS ETHREAD KPROCESS (PCB) NT Kernel KTHREAD

7 NT Process Descriptor Kernel process object including: Pointer to the page directory Kernel & user time Process base priority Process state List of the Kernel thread descriptors that are using this process

8 NT Process Descriptor (cont) Parent identification Exit status Creation and termination times. Memory status Security information executable image Process priority class used by the thread scheduler. A list of handles used by this process A pointer to Win32-specific information

9 Address Space Primary Memory Process Address Space Files Mailboxes System services Other objects

10 Defining the Address Space Some parts are built into the environment Files System services Some parts are imported at runtime Mailboxes Network connections Memory address block is created at compile time

11 The Compile Time Component Source Modules Translator Relocatable Modules Link Editor Absolute Program Primary Memory Loader Executable Program

12 Resource Manager Resource Manager Request Allocate Release Release Allocate Process Release Allocate Resource Pool

13 Process State (Version 1) Done Request Request Running Schedule Allocate Start Blocked Ready

14 Creating a Process Have seen UNIX fork & exec Derived from FORK, JOIN, & QUIT FORK(label): Create another process in the same address space beginning execution at instruction label QUIT(): Terminate the process. JOIN(count): disableinterrupts(); count--; if(count > 0) QUIT(); enableinterrupts();

15 Example proca() { while(true) { <compute section A1>; update(x); <compute section A2>; retrieve(y); } } procb() { while(true) { retrieve(x); <compute section B1>; update(y); <compute section B2>; } } Process A x y Process B

16 L0: count = 2; <compute section A1>; update(x); FORK(L2); <compute section A2>; L1: JOIN(count); retrieve(y); goto L0; L2: retrieve(x); <compute section B1>; update(y); FORK(L3); goto L1; L3: <compute section B2> QUIT(); Example (cont)

17 Example (cont) L0: count = 2; <compute section A1>; update(x); FORK(L2); <compute section A2>; L1: JOIN(count); retrieve(y); goto L0; L2: retrieve(x); <compute section B1>; update(y); FORK(L3); goto L1; L3: <compute section B2> QUIT(); L0: count = 2; <compute section A1>; update(x); FORK(L2); retrieve(y); <compute section B1> update(y>; FORK(L3) L1: JOIN(count); retrieve(y); goto L0; L2: <compute section A2>; goto L1; L3: <compute section B2> QUIT();

18 Process Hierarchies Parent-child relationship may be significant: parent controls children s execution Request Ready-Active Blocked-Active Done Request Running Yield Schedule Suspend Suspend Start Activate Ready-Suspended Allocate Suspend Allocate Blocked-Suspended Activate