[PPT] - I nt roduct ion t o Lab 2 I nt roduct ion t o Lab 2 I nt roduct ion PowerPoint Presentation

SLIDE 1

Slides by Magnus Almgren

I nt roduct ion t o Lab 2 I nt roduct ion t o Lab 2 I nt roduct ion t o Lab 2 I nt roduct ion t o Lab 2

EDA092 EDA092 – Oper at ing Syst ems Oper at ing Syst ems 2008 2008-02 02-18 18 Wolf gang J ohn Wolf gang J ohn

SLIDE 2

Slides by Magnus Almgren

Overview of OSP

An Environment f or

Operat ing Syst em Proj ect s

Simulat es an operat ing syst em (surprise!)
Consist s of modules t hat execut es

dif f erent operat ing syst em f unct ions, such as

– Scheduling of CPU (lab 2.1) – Vir t ual Memor y Management (lab 2.2) – File Access (lab 2.3)

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Slides by Magnus Almgren

OSP Modules: Overview

CPU DI ALOG SI MCORE I NTER DEVI NT PAGEI NT TI MEI NT DEVI CES MEMORY FI LES

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Slides by Magnus Almgren

OSP Modules: Overview

CPU DI ALOG I NTER DEVI NT PAGEI NT TI MEI NT SI MCORE DEVI CES MEMORY FI LES Lab 2.1 Lab 2.2

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Slides by Magnus Almgren

OSP Modules: Overview

CPU DI ALOG SI MCORE I NTER DEVI NT PAGEI NT TI MEI NT DEVI CES MEMORY FI LES

CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES

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Slides by Magnus Almgren

OSP Modules: Overview

CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES

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Slides by Magnus Almgren

OSP Modules: Misc

RESOURCES –resource management
DEVI CES

–disk access

SOCKETS

–process communicat ion

PROTOCOLS –prot ocols used f or t he

SOCKET module

CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES

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Slides by Magnus Almgren

OSP Modules: SimCore

CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES

SimCore – Main Par t of Syst em

– Gener at es event s

St art and t erminat ion of processes
Virt ual memory ref erences
Timer int errupt s
Read/ writ e t o ext ernal devices
I nt errupt s f rom ext ernal devices

– Par amet er s of t he simulat ion cont r ols t he simulat ion – Collect s st at ist ics about r esour ce allocat ion

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Slides by Magnus Almgren

OSP Modules: SimCore

CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES

Har dwar e of OSP CPU

– I nt er val Timer – Clock – I nt er r upt vect or – Base r egist er f or page t ables – Disk access

Memor y

– Vir t ual memor y wit h paging: PAGE_TBL

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Slides by Magnus Almgren

Lab 2.1: CPU Scheduling
Three Process St at es

(+done:zombie)

Each process has a

Process Control Block

OSP Modules: CPU

CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES

blocked ready running sleep wakeup t imer int errupt dispat ch

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Slides by Magnus Almgren

struct pcb_node { /* f r om cpu.c */

int pcb_id; /*

PCB id

*/ int size; /*

process size in byt es; assigned by SI MCORE

*/ int creation_time; /*

assigned by SI MCORE

*/ int last_dispatch; /*

last t ime t he process was dispat ched

*/ int last_cpuburst; /*

lengt h of t he previous CPU burst

*/ int accumulated_cpu; /*

accumulat ed CPU t ime

*/ PAGE_TBL *page_tbl; /*

page t able associat ed wit h t he PCB

*/ STATUS status; /*

st at us of process: running, ready, wait ing, done

*/ EVENT *event; /*

event upon which process may be suspended

*/ int priority; /*

user-def ined priorit y; used f or scheduling

*/ PCB *next; /*

next PCB in what ever queue

*/ PCB *prev; /*

previous PCB in what ever queue

*/ int *hook; /*

can hook up anyt hing here

*/

};

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Slides by Magnus Almgren

Lab 2.1: Round Robin Scheduling

Round Robin = Signing pet it ions w/ out

showing who signed f irst

Circular queue of processes ready t o

execut e

No priorit y (regular RR)
Each process execut es unt il it

– Ter minat es – Wait s (f or a r esour ce) – Runs out of t ime quant a (‘t imer int er r upt ’)

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Slides by Magnus Almgren

1 Ready Queue 2 3 4 CPU Disk Queue

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Slides by Magnus Almgren

1 Ready Queue 2 3 4 CPU Disk Queue Out of t ime

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Slides by Magnus Almgren

2 Ready Queue 3 4 1 CPU Disk Queue

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Slides by Magnus Almgren

2 Ready Queue 3 4 1 CPU Disk Queue Out of t ime

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Slides by Magnus Almgren

3 Ready Queue 4 1 2 CPU Disk Queue

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Slides by Magnus Almgren

3 Ready Queue 4 1 2 CPU Disk Queue Wait f or disk access 3

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Slides by Magnus Almgren

4 Ready Queue 1 2 CPU Disk Queue 3 4 Wait f or disk access

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Slides by Magnus Almgren

1 Ready Queue 2 CPU Disk Queue 3 4 I nt errupt : Disk access

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Slides by Magnus Almgren

2 Ready Queue CPU 3 3 Disk Queue I nt errupt : Disk access 4

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Slides by Magnus Almgren

2 Ready Queue CPU 3 4 Disk Queue I nt errupt : Disk access Process Terminat ion

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Slides by Magnus Almgren

Lab 2.1 Requirement s?

Round Robin Scheduling in OSP:

I mplement a r eady queue, and move pr ocesses f r om r unning and r eady queue.

1. Key I nf ormat ion: OSP 1.6 (impossible t o do lab wit hout it !!!) 2. Main Working File: cpu.c 3. Need: Linked List f or Round Robin …

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Slides by Magnus Almgren

/ *************************************************************/ / * Module CPU */ / * Ext ernal Declarat ions */ / *************************************************************/

/ * OSP const ant */

#define MAX_PAGE 16 / * max size of page t ables */

/ * OSP enumer at ion const ant s */

typedef enum { false, true / * t he boolean dat a t ype */ } BOOL; typedef enum { running,ready,waiting,done / * t ypes of st at us */ } STATUS;

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Slides by Magnus Almgren

/ * ext er nal t ype def init ions */

typedef struct page_entry_node PAGE_ENTRY; typedef struct page_tbl_node PAGE_TBL; typedef struct event_node EVENT; typedef struct pcb_node PCB;

/ * ext er nal dat a st r uct ur es */

struct page_entry_node { int frame_id; / * f rame id holding t his page */ BOOL valid; / * page in main memory : valid = t rue; not : f alse */ BOOL ref; / * set t o t rue every t ime page is ref erenced AD */ int *hook; / * can hook up anyt hing here */ }; struct page_tbl_node { PCB *pcb; / * PCB of t he process in quest ion */ PAGE_ENTRY page_entry[MAX_PAGE]; int *hook; / * can hook up anyt hing here */ };

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Slides by Magnus Almgren

struct pcb_node {

int pcb_id; /*

PCB id

*/ int size; /*

process size in byt es; assigned by SI MCORE

*/ int creation_time; /*

assigned by SI MCORE

*/ int last_dispatch; /*

last t ime t he process was dispat ched

*/ int last_cpuburst; /*

lengt h of t he previous CPU burst

*/ int accumulated_cpu; /*

accumulat ed CPU t ime

*/ PAGE_TBL *page_tbl; /*

page t able associat ed wit h t he PCB

*/ STATUS status; /*

st at us of process

*/ EVENT *event; /*

event upon which process may be suspended

*/ int priority; /*

user-def ined priorit y; used f or scheduling

*/ PCB *next; /*

next PCB in what ever queue

*/ PCB *prev; /*

previous PCB in what ever queue

*/ int *hook; /*

can hook up anyt hing here

*/

};

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Slides by Magnus Almgren

/ * ext er nal var iables */

extern PAGE_TBL *PTBR; / * page t able base regist er */ extern int Quantum; / * global t ime quant um; cont ains t he value ent ered at t he beginning or changed at snapshot . Has no ef f ect on t imer int errupt s, unless passed t o set _t imer() */

/ * ext er nal r out ines */

extern prepage(/ * pcb */ ); extern int start_cost(/ * pcb */ ); / * PCB *pcb; */ extern set_timer(/ * t ime_quant um */ ); / * int t ime_quant um; */ extern int get_clock();

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Slides by Magnus Almgren

/ *******************************************************/ / * Module CPU */ / * I nt ernal Rout ines */ / *******************************************************/ void cpu_init() { } void dispatch() { } void insert_ready(pcb) PCB *pcb; { } / * end of module */ lot s of smart code ready t o run? round robin

Her e is most ly wher e you add your code f or lab 2.1!

I mport ant : Check t he I nt ro t o OSP f or all necessary st eps.

SLIDE 29

Slides by Magnus Almgren

Building a Linked List

Assume t hat a list of posit ions (x,y) shall be

implement ed in t he C language using linked list s. Det er mine a suit able t ype declar at ion and wr it e f unct ions t o do t he f ollowing:

– Cr eat e an empt y list – Add an element (x,y) t o a list – Sear ch f or an element (x,y) in a list and r emove it if pr esent in t he list

Previous: Next : Y: x: Previous: Next : Y: x: Previous: Next : Y: x: Previous: Next : Y: x: Head:

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Slides by Magnus Almgren

I nt roduct ion t o LL

Double-linked, circular list
Usef ul t o have synonym f or t he last

element t oo

Previous: Next : Y: x: Previous: Next : Y: x: Previous: Next : Y: x: Previous: Next : Y: x: Head: t ail: head-> previous

SLIDE 31

Slides by Magnus Almgren

Lab 2.2 Memory Management

OSP Modules

– MEMORY – PAGEI NT

Caref ully read OSP 1.4.3 and 1.5 !!!
Experiment wit h paramet ers t o

reduce t he page f ault s

CP U DI ALOG SI MCORE I NTER DEVI NT P AGEI NT TI MEI NT DEVI CES MEMORY FI LES

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Slides by Magnus Almgren

Memory Management

Algorit hms t o replace pages

– FI FO – Opt imal Algorit hm (I maginary) – LRU (Least Recent ly Used)

Good but dif f icult t o implement
Second-Chance Algor it hm, w/ r ef er ence bit

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Slides by Magnus Almgren

2nd Chance Clock Algorit hm

1 1 1 1 1 1 next vict im

ref erence bit s pages ref erence bit s pages

Page 337 in Operat ing Syst em Concept s