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Operating Systems ‫التشغيل‬ ‫نظم‬ ‫رقم‬ ‫المحاضرة‬ 2 Operating-System Structures 10/1/2022 1 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Agenda  Computer-System Organization • Interrupt • Storage Structure • I/O Structure  Computer-System Architecture • Single-Processor • Multi-Processors • Clustered System  Operating-System Operations • Multi-Programming and Multi-Tasking • Dual Mode  Resource Management • Process Management • Memory Management • Storage Management • Protection and Security 10/1/2022 2 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
COMPUTER-SYSTEM ORGANIZATION 10/1/2022 3 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Computer System Structure  Computer system can be divided into four components: • Hardware – provides basic computing resources • CPU, memory, I/O devices • Operating system • Controls and coordinates use of hardware among various applications and users • Application programs – define the ways in which the system resources are used to solve the computing problems of the users • Word processors, compilers, web browsers, database systems, video games • Users • People, machines, other computers 10/1/2022 4 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Computer System  “The one program running at all times on the computer” is the kernel.  Everything else is either • a system program (ships with the operating system) , or • an application program. 10/1/2022 5 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Computer Startup  Bootstrap program is loaded at power-up or reboot • Typically stored in ROM or EPROM, generally known as firmware • Initializes all aspects of system • Loads operating system kernel and starts execution 10/1/2022 6 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Computer System Organization  Computer-system operation • One or more CPUs, device controllers connect through common bus providing access to shared memory • Concurrent execution of CPUs and devices competing for memory cycles 10/1/2022 7 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Computer-System Operation  I/O devices and the CPU can execute concurrently ‫اجهزة‬ ‫االدخال‬ ‫واالخراج‬ ‫والمعالج‬ ‫يمكن‬ ‫ان‬ ‫تنفذ‬ ‫بالتزامن‬  Each device controller is in charge of a particular device type ‫كل‬ ‫متحكم‬ ‫مخصص‬ ‫لنوع‬ ‫معين‬ ‫من‬ ‫االجهزة‬  Each device controller has a local buffer ‫كل‬ ‫متحكم‬ ‫له‬ ‫مخزن‬ ‫داخلي‬  CPU moves data from/to main memory to/from local buffers ‫المعالج‬ ‫ينقل‬ ‫البيانات‬ ‫من‬ ‫والى‬ ‫الذاكرة‬ ‫من‬ ‫والى‬ ‫المخزن‬ ‫الداخلي‬  Device controller informs CPU that it has finished its operation by causing an interrupt ‫المتحكم‬ ‫يعلم‬ ‫المعالج‬ ‫بانتهاء‬ ‫عمله‬ ‫باستحداث‬ ‫قاطع‬ 10/1/2022 8 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Common Functions of Interrupts  The occurrence of an event is usually signaled by an interrupt from either the hardware or the software. ‫ظهور‬ ‫حدث‬ ‫عادة‬ ‫يشار‬ ‫اليه‬ ‫بالمقاطعة‬ ‫سواء‬ ‫من‬ ‫الهاردوير‬ ‫او‬ ‫السوفتوير‬  Hardware may trigger an interrupt at any time by sending a signal to the CPU, usually by way of the system bus. ‫قد‬ ‫تتسبب‬ ‫األجهزة‬ ‫في‬ ‫حدوث‬ ‫مقاطعة‬ ‫في‬ ‫أي‬ ‫وقت‬ ‫عن‬ ‫طريق‬ ‫إرسال‬ ‫إشارة‬ ‫إلى‬ ‫وحدة‬ ‫المعالجة‬ ‫المركزية‬ ، ً ‫عادة‬ ‫عن‬ ‫طريق‬ ‫ناقل‬ ‫النظام‬ .  Software may trigger an interrupt by executing a special operation called a system call (also called a monitor call).  ‫قد‬ ‫يتسبب‬ ‫البرنامج‬ ‫في‬ ‫حدوث‬ ‫مقاطعة‬ ‫عن‬ ‫طريق‬ ‫تنفيذ‬ ‫عملية‬ ‫خاصة‬ ‫تسمى‬ ‫ا‬ ‫ستدعاء‬ ‫النظام‬ ( ‫تسمى‬ ‫ا‬‫أيض‬ ‫مكالمة‬ ‫الشاشة‬ ) . 10/1/2022 9 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Common Functions of Interrupts  Interrupts are an important part of a computer architecture. ‫المقاطعات‬ ‫هي‬ ‫جزء‬ ‫مهم‬ ‫من‬ ‫معمارية‬ ‫الكمبيوتر‬ .  Each computer design has its own interrupt mechanism, but several functions are common. ‫كل‬ ‫تصميم‬ ‫كمبيوتر‬ ‫له‬ ‫آليه‬ ‫المقاطعة‬ ‫الخاصة‬ ‫به‬ ، ‫ولكن‬ ‫هناك‬ ‫العديد‬ ‫من‬ ‫الوظائف‬ ‫الشائعة‬ .  Interrupt transfers control to the interrupt service routine generally, through the interrupt vector, which contains the addresses of all the service routines ‫تنقل‬ ‫المقاطعة‬ ‫التحكم‬ ‫إلى‬ ‫روتين‬ ‫خدمة‬ ‫المقاطعة‬ ‫بشكل‬ ‫عام‬ ، ‫من‬ ‫خالل‬ ‫ناقل‬ ‫المقاطعة‬ ، ‫الذي‬ ‫يحتوي‬ ‫على‬ ‫عناو‬ ‫ين‬ ‫جميع‬ ‫إجراءات‬ ‫الخدمة‬  Interrupt architecture must save the address of the interrupted instruction ‫يجب‬ ‫أن‬ ‫تحفظ‬ ‫بنية‬ ‫المقاطعة‬ ‫عنوان‬ ‫التعليمات‬ ‫التي‬ ‫تمت‬ ‫مقاطعتها‬ .  A trap or exception is a software-generated interrupt caused either by an error or a user request ‫االعتراض‬ ‫أو‬ ‫االستثناء‬ ‫هو‬ ‫مقاطعة‬ ‫ينتج‬ ‫عن‬ ‫البرامج‬ ‫إما‬ ‫عن‬ ‫حدوث‬ ‫خطأ‬ ‫أو‬ ‫طلب‬ ‫مستخدم‬  An operating system is interrupt driven ‫نظام‬ ‫التشغيل‬ ‫هو‬ ‫معتمد‬ ‫على‬ ‫المقاطعة‬ 10/1/2022 10 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Interrupt Handling  The operating system preserves the state of the CPU by storing registers and the program counter ‫يحافظ‬ ‫نظام‬ ‫التشغيل‬ ‫على‬ ‫حالة‬ ‫المعالج‬ ‫من‬ ‫خالل‬ ‫تخزين‬ ‫الس‬ ‫جالت‬ ‫وعداد‬ ‫البرنامج‬ .  Separate segments of code determine what action should be taken for each type of interrupt ‫تعليمات‬ ‫برمجية‬ ‫منفصلة‬ ‫تحدد‬ ‫اإلجراء‬ ‫الذي‬ ‫يجب‬ ‫اتخاذه‬ ‫لك‬ ‫ل‬ ‫نوع‬ ‫من‬ ‫أنواع‬ ‫المقاطعة‬ 10/1/2022 11 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Interrupt Timeline 10/1/2022 12 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
STORAGE STRUCTURE 10/1/2022 13 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Storage Structure  Main memory – only large storage media that the CPU can access directly ‫الذاكرة‬ ‫الرئيسية‬ : ‫وسيط‬ ‫تخزين‬ ‫يستطيع‬ ‫المعالج‬ ‫الوصول‬ ‫اليه‬ ‫مباشرة‬ • Random access • Typically volatile  Secondary storage – extension of main memory that provides large nonvolatile storage capacity ‫الذاكرة‬ ‫الثانوية‬ : ‫امتداد‬ ‫للذاكرة‬ ‫الرئيسية‬ ‫ولها‬ ‫سعة‬ ‫عالية‬ ‫غير‬ ‫متطايرة‬  Hard disks – rigid metal or glass platters covered with magnetic recording material • Disk surface is logically divided into tracks, which are subdivided into sectors • The disk controller determines the logical interaction between the device and the computer  Solid-state disks – faster than hard disks, nonvolatile • Various technologies • Becoming more popular 10/1/2022 14 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Storage Hierarchy  Storage systems organized in hierarchy • Speed • Cost • Volatility  Caching – copying information into faster storage system; main memory can be viewed as a cache for secondary storage  Device Driver for each device controller to manage I/O • Provides uniform interface between controller and kernel 10/1/2022 15 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Storage-Device Hierarchy 10/1/2022 16 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
PC Structure - Memory Hierarchy  ‫تتكونًهرميةًالذاكرةًمنًالتالي‬ : • ً‫المسجالت‬ registers • ً‫الذاكرةًالمخبأة‬ ) ‫الكاش‬ ( cache • ً‫الذاكرةًالرئيسية‬ ) ‫الرام‬ ( main memory • ًٍ‫الذاكرةًالثانوية‬ Secondary Memory 10/1/2022 17 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
PC Structure - Memory Hierarchy 10/1/2022 18 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
PC Structure - Memory Hierarchy  ً‫هنالكًعواملًتؤثرًفيًهرميةًالذاكرةًهي‬ : • ‫التطاير‬ volatility • ‫السرعة‬ Speed • ‫السعة‬ Capacity • ‫السعر‬ Price 10/1/2022 19 ‫التطاير‬ ‫زيادة‬ OPERATING SYSTEMS– AL-NASSER UNIVERSITY
PC Structure - Memory 10/1/2022 20 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Caching  Important principle, performed at many levels in a computer (in hardware, operating system, software) ‫مصطلح‬ ‫مهم‬ ‫يوجد‬ ‫في‬ ‫اكثر‬ ‫من‬ ‫مستوى‬ ‫في‬ ‫الكمبيوتر‬  Information in use copied from slower to faster storage temporarily ‫المعلومات‬ ‫المستخدمة‬ ‫تنسخ‬ ‫من‬ ‫التخزين‬ ‫االبطا‬ ‫الى‬ ‫االسرع‬ ‫موقتا‬  Faster storage (cache) checked first to determine if information is there • If it is, information used directly from the cache (fast) • If not, data copied to cache and used there  Cache smaller than storage being cached • Cache management important design problem • Cache size and replacement policy 10/1/2022 21 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
I/O STRUCTURE 10/1/2022 22 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Direct Memory Access Structure  Used for high-speed I/O devices able to transmit information at close to memory speeds  Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention  Only one interrupt is generated per block, rather than the one interrupt per byte 10/1/2022 23 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
A von Neumann architecture How a Modern Computer Works 10/1/2022 24 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
COMPUTER-SYSTEM ARCHITECTURE 10/1/2022 25 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Computer-System Architecture  Most systems use a single general-purpose processor • Most systems have special-purpose processors as well  Multiprocessors systems growing in use and importance • Also known as parallel systems, tightly-coupled systems • Advantages include: • Increased throughput • Economy of scale • Increased reliability – graceful degradation or fault tolerance • Two types: • Asymmetric Multiprocessing – each processor is assigned a specific task. • Symmetric Multiprocessing – each processor performs all tasks 10/1/2022 26 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Symmetric Multiprocessing Architecture 10/1/2022 27 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
A Dual-Core Design 10/1/2022 28 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Clustered Systems  Like multiprocessor systems, but multiple systems working together • Usually sharing storage via a storage-area network (SAN) • Provides a high-availability service which survives failures •Asymmetric clustering has one machine in hot-standby mode •Symmetric clustering has multiple nodes running applications, monitoring each other • Some clusters are for high-performance computing (HPC) •Applications must be written to use parallelization 10/1/2022 29 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Clustered Systems 10/1/2022 30 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
OPERATING-SYSTEM OPERATIONS 10/1/2022 31 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Operating System Structure  Multiprogramming (Batch system) needed for efficiency • Single user cannot keep CPU and I/O devices busy at all times • Multiprogramming organizes jobs (code and data) so CPU always has one to execute • A subset of total jobs in system is kept in memory • One job selected and run via job scheduling • When it has to wait (for I/O for example), OS switches to another job  Timesharing (multitasking) is logical extension in which CPU switches jobs so frequently that users can interact with each job while it is running, creating interactive computing • Response time should be < 1 second • Each user has at least one program executing in memory process • If several jobs ready to run at the same time  CPU scheduling • If processes don’t fit in memory, swapping moves them in and out to run • Virtual memory allows execution of processes not completely in memory 10/1/2022 32 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Operating-System Operations  Interrupt driven (hardware and software) • Hardware interrupt by one of the devices ‫مقاطعة‬ ‫الهاردوير‬ ‫تكون‬ ‫بواسطة‬ ‫احد‬ ‫االجهزة‬ • Software interrupt (exception or trap): • Software error (e.g., division by zero) ‫اخطاء‬ ‫البرامج‬ • Request for operating system service ‫طلب‬ ‫خدمة‬ ‫من‬ ‫نظام‬ ‫التشغيل‬ • Other process problems include infinite loop, processes modifying each other or the operating system ‫مشاكل‬ ‫العمليات‬ ‫االخرى‬ ‫المتضمنة‬ ‫التكرار‬ ‫الالنهائي‬ ، ‫تعديالت‬ ‫العمليات‬ ‫على‬ ‫بع‬ ‫ضها‬ ‫او‬ ‫على‬ ‫نظام‬ ‫التشغيل‬ 10/1/2022 33 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Operating-System Operations  Dual-mode operation allows OS to protect itself and other system components. ‫يتيح‬ ‫التشغيل‬ ‫ثنائي‬ ‫الوضع‬ ‫لنظام‬ ‫التشغيل‬ ‫حماية‬ ‫نفسه‬ ‫ومكونات‬ ‫النظام‬ ‫األخرى‬ . • User mode and kernel mode ‫وضع‬ ‫المستخدم‬ ‫ووضع‬ ‫النواة‬ . • Mode bit provided by hardware ‫يتم‬ ‫توفير‬ ‫بت‬ ‫الوضع‬ ‫بواسطة‬ ‫األجهزة‬ • Provides ability to distinguish when system is running user code or kernel code ‫يوفر‬ ‫القدرة‬ ‫على‬ ‫التمييز‬ ‫اذا‬ ‫كان‬ ‫النظام‬ ‫في‬ ‫طور‬ ‫تشغيل‬ ‫كود‬ ‫المستخدم‬ ‫أو‬ ‫كود‬ ‫النواة‬ • Some instructions designated as privileged, only executable in kernel mode ‫بعض‬ ‫التعليمات‬ ‫المصنفة‬ ‫على‬ ‫أنها‬ ‫ذات‬ ‫امتياز‬ ، ‫قابلة‬ ‫للتنفيذ‬ ‫فقط‬ ‫في‬ ‫وضع‬ ‫النواة‬ • System call changes mode to kernel, return from call resets it to user ‫استدعاء‬ ‫النظام‬ ‫يغيرالوضع‬ ‫إلى‬ ‫النواة‬ ، ‫والعودة‬ ‫من‬ ‫االستدعاء‬ ‫يعين‬ ‫الوضع‬ ‫إلى‬ ‫المستخدم‬ 10/1/2022 34 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Transition from User to Kernel Mode  Timer to prevent infinite loop / process hogging resources • Timer is set to interrupt the computer after some time period ‫ضبط‬ ‫المؤقت‬ ‫على‬ ‫مقاطعة‬ ‫الكمبيوتر‬ ‫بعد‬ ‫فترة‬ ‫زمنية‬ . • Keep a counter that is decremented by the physical clock. ‫االحتفاظ‬ ‫بعداد‬ ‫يتناقص‬ ‫بواسطة‬ ‫الساعة‬ ‫الفعلية‬ . • Operating system set the counter. ‫نظام‬ ‫التشغيل‬ ‫يضبط‬ ‫العداد‬ • When counter zero generate an interrupt ‫عندما‬ ‫يكون‬ ‫العداد‬ ‫صفر‬ ‫يتم‬ ‫انشاء‬ ‫المقاطعة‬ • Set up before scheduling process to regain control or terminate program that exceeds allotted time ‫التهيئة‬ ‫قبل‬ ‫جدولة‬ ‫العملية‬ ‫الستعادة‬ ‫التحكم‬ ‫أو‬ ‫إنهاء‬ ‫البرنامج‬ ‫الذي‬ ‫تجاوز‬ ‫الوقت‬ ‫المخص‬ ‫ص‬ 10/1/2022 35 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Transition from User to Kernel Mode 10/1/2022 36 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
RESOURCE MANAGEMENT 10/1/2022 37 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Process Management  A process is a program in execution. It is a unit of work within the system. Program is a passive entity, process is an active entity. ‫العملية‬ ‫عبارة‬ ‫عن‬ ‫برنامج‬ ‫قيد‬ ‫التنفيذ‬ . ‫إنها‬ ‫وحدة‬ ‫عمل‬ ‫داخل‬ ‫النظام‬ ، ‫البرنامج‬ ‫كيان‬ ‫غير‬ ‫فعال‬ ، ‫والعملية‬ ‫كيان‬ ‫نشط‬ .  Process needs resources to accomplish its task • CPU, memory, I/O, files • Initialization data  Process termination requires reclaim of any reusable resources ‫يتطلب‬ ‫إنهاء‬ ‫العملية‬ ‫استعادة‬ ‫أي‬ ‫موارد‬ ‫قابلة‬ ‫إلعادة‬ ‫االستخدام‬  Single-threaded process has one program counter specifying location of next instruction to execute ‫تحتوي‬ ‫العملية‬ ‫أحادية‬ ‫الخيوط‬ ‫على‬ ‫عداد‬ ‫برنامج‬ ‫واحد‬ ‫يحدد‬ ‫موقع‬ ‫التعليمات‬ ‫التالية‬ ‫للتنف‬ ‫يذ‬ • Process executes instructions sequentially, one at a time, until completion ‫تنفذ‬ ‫العملية‬ ‫التعليمات‬ ‫بالتتابع‬ ، ‫ا‬‫واحد‬ ‫تلو‬ ‫اآلخر‬ ، ‫حتى‬ ‫اكتمالها‬ 10/1/2022 38 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Process Management  Multi-threaded process has one program counter per thread ‫تحتوي‬ ‫العملية‬ ‫متعددة‬ ‫الخيوط‬ ‫على‬ ‫عداد‬ ‫برنامج‬ ‫واحد‬ ‫لكل‬ ‫خيط‬  Typically system has many processes, some user, some operating system running concurrently on one or more CPUs ً ‫عادة‬ ‫ما‬ ‫يحتوي‬ ‫النظام‬ ‫على‬ ‫العديد‬ ‫من‬ ‫العمليات‬ ، ‫بعضها‬ ‫للمستخدم‬ ، ‫وبعضها‬ ‫لنظام‬ ‫التشغيل‬ ‫تعمل‬ ‫ب‬ ‫شكل‬ ‫متزامن‬ ‫في‬ ‫معالج‬ ‫واحد‬ ‫أو‬ ‫أكثر‬ • Concurrency by multiplexing the CPUs among the processes / threads ‫التزامن‬ ‫عن‬ ‫طريق‬ ‫تنقل‬ ‫المعالج‬ ‫بين‬ ‫العمليات‬ / ‫الخيوط‬  The operating system is responsible for the following activities in connection with process management: • Creating and deleting both user and system processes ‫انشاء‬ ‫او‬ ‫حذف‬ ‫العمليات‬ • Suspending and resuming processes ‫تعليق‬ ‫واستئناف‬ ‫العمليات‬ • Providing mechanisms for process synchronization ‫توفير‬ ‫آليات‬ ‫لمزامنة‬ ‫العملية‬ • Providing mechanisms for process communication ‫توفير‬ ‫آليات‬ ‫لعملية‬ ‫االتصال‬ • Providing mechanisms for deadlock handling ‫توفير‬ ‫آليات‬ ‫للتعامل‬ ‫مع‬ ‫الطريق‬ ‫المسدود‬ 10/1/2022 39 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Memory Management  To execute a program all (or part) of the instructions must be in memory ‫لتنفيذ‬ ‫برنامج‬ ، ‫يجب‬ ‫أن‬ ‫تكون‬ ‫جميع‬ ‫التعليمات‬ ( ‫أو‬ ‫جزء‬ ‫منها‬ ) ‫في‬ ‫الذاكرة‬ .  All (or part) of the data that is needed by the program must be in memory. ‫يجب‬ ‫أن‬ ‫تكون‬ ‫جميع‬ ( ‫أو‬ ‫جزء‬ ) ‫البيانات‬ ‫التي‬ ‫يحتاجها‬ ‫البرنامج‬ ‫في‬ ‫الذاكرة‬ .  Memory management determines what is in memory and when ‫تحدد‬ ‫إدارة‬ ‫الذاكرة‬ ‫ما‬ ‫هو‬ ‫موجود‬ ‫في‬ ‫الذاكرة‬ ‫ومتى‬ • Optimizing CPU utilization and computer response to users ‫تحسين‬ ‫استخدام‬ ‫وحدة‬ ‫المعالجة‬ ‫المركزية‬ ‫واستجابة‬ ‫الكمبيوتر‬ ‫للمستخدمين‬  Memory management activities • Keeping track of which parts of memory are currently being used and by whom ‫تتبع‬ ‫أي‬ ‫أجزاء‬ ‫من‬ ‫الذاكرة‬ ‫يتم‬ ‫استخدامها‬ ‫ا‬‫حالي‬ ‫ومن‬ ‫قبل‬ ‫من‬ • Deciding which processes (or parts thereof) and data to move into and out of memory ‫تحديد‬ ‫العمليات‬ ( ‫أو‬ ‫أجزاء‬ ‫منها‬ ) ‫والبيانات‬ ‫التي‬ ‫سيتم‬ ‫نقلها‬ ‫إلى‬ ‫الذاكرة‬ ‫وخارجها‬ • Allocating and deallocating memory space as needed ‫تخصيص‬ ‫مساحة‬ ‫الذاكرة‬ ‫وإلغاء‬ ‫تخصيصها‬ ‫حسب‬ ‫الحاجة‬ 10/1/2022 40 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Storage Management  OS provides uniform, logical view of information storage ‫يوفر‬ ‫نظام‬ ‫التشغيل‬ ‫رؤية‬ ‫موحدة‬ ‫ومنطقية‬ ‫لتخزين‬ ‫المعلومات‬ • Abstracts physical properties to logical storage unit - file ‫يلخص‬ ‫الخصائص‬ ‫الفيزيائية‬ ‫لوحدة‬ ‫التخزين‬ ‫المنطقية‬ - ‫الملف‬ • Each medium is controlled by device (i.e., disk drive, tape drive) ‫يتم‬ ‫التحكم‬ ‫في‬ ‫كل‬ ‫وسيط‬ ‫بواسطة‬ ‫جهاز‬ ( ‫أي‬ ‫محرك‬ ‫األقراص‬ ‫ومحرك‬ ‫الشريط‬ ) •Varying properties include access speed, capacity, data- transfer rate, access method (sequential or random) ‫تشمل‬ ‫الخصائص‬ ‫المتغيرة‬ ‫سرعة‬ ‫الوصول‬ ، ‫والسعة‬ ، ‫ومعدل‬ ‫نقل‬ ‫البيانا‬ ‫ت‬ ، ‫وطريقة‬ ‫الوصول‬ ( ‫تسلسلي‬ ‫أو‬ ‫عشوائي‬ ) 10/1/2022 41 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Storage Management  File-System management • Files usually organized into directories ‫عادة‬ ‫ما‬ ‫يتم‬ ‫تنظيم‬ ‫الملفات‬ ‫في‬ ‫أدلة‬ • Access control on most systems to determine who can access what ‫التحكم‬ ‫في‬ ‫الوصول‬ ‫إلى‬ ‫معظم‬ ‫األنظمة‬ ‫لتحديد‬ ‫من‬ ‫يمكنه‬ ‫الوصول‬ ‫إلى‬ ‫ماذا‬ • OS activities include • Creating and deleting files and directories ‫إنشاء‬ ‫وحذف‬ ‫الملفات‬ ‫واألدلة‬ • Primitives to manipulate files and directories ‫األساسيات‬ ‫لمعالجة‬ ‫الملفات‬ ‫واألدلة‬ • Mapping files onto secondary storage ‫تعيين‬ ‫الملفات‬ ‫على‬ ‫التخزين‬ ‫الثانوي‬ • Backup files onto stable (non-volatile) storage media ‫النسخ‬ ‫االحتياطي‬ ‫للملفات‬ ‫على‬ ‫وسائط‬ ‫تخزين‬ ‫مستقرة‬ ( ‫غير‬ ‫متطايرة‬ ) 10/1/2022 42 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Mass-Storage Management  Usually disks used to store data that does not fit in main memory or data that must be kept for a “long” period of time ‫عادة‬ ‫األقراص‬ ‫المستخدمة‬ ‫لتخزين‬ ‫البيانات‬ ‫التي‬ ‫تتسع‬ ‫في‬ ‫الذاكرة‬ ‫الرئيسية‬ ‫أو‬ ‫البيانات‬ ‫التي‬ ‫يجب‬ ‫االحتفاظ‬ ‫بها‬ ‫لف‬ ‫ترة‬ " ‫طويلة‬ " ‫من‬ ‫الوقت‬  Proper management is of central importance ‫اإلدارة‬ ‫السليمة‬ ‫لها‬ ‫أهمية‬ ‫مركزية‬  OS activities • Free-space management ‫إدارة‬ ‫المساحة‬ ‫الخالية‬ • Storage allocation ‫تخصيص‬ ‫التخزين‬ • Disk scheduling ‫جدولة‬ ‫القرص‬ • Partitioning ‫التجزئة‬ • Protection ‫الحماية‬ 10/1/2022 43 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
I/O Subsystem  One purpose of OS is to hide peculiarities of hardware devices from the user ‫يتمثل‬ ‫أحد‬ ‫أهداف‬ ‫نظام‬ ‫التشغيل‬ ‫في‬ ‫إخفاء‬ ‫خصائص‬ ‫األجهزة‬ ‫عن‬ ‫المستخدم‬  I/O subsystem responsible for • Memory management of I/O including buffering (storing data temporarily while it is being transferred), caching (storing parts of data in faster storage for performance), spooling (the overlapping of output of one job with input of other jobs) ‫ادارة‬ ‫الذاكرة‬ ‫لإلدخال‬ ‫واالخراج‬ ‫تتضمن‬ ‫التخزين‬ ‫المؤقت‬ ، ‫الذاكرة‬ ‫المخبأة‬ ، ‫المسالك‬ • General device-driver interface ‫واجهة‬ ‫برنامج‬ ‫تشغيل‬ ‫الجهاز‬ ‫العامة‬ • Drivers for specific hardware devices ‫التعريفات‬ ‫ألجهزة‬ ‫معينة‬ 10/1/2022 44 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
Protection and Security  Protection – any mechanism for controlling access of processes or users to resources defined by the OS ‫الحماية‬ – ‫هي‬ ‫أي‬ ‫آلية‬ ‫للتحكم‬ ‫في‬ ‫وصول‬ ‫العمليات‬ ‫أو‬ ‫المستخدمين‬ ‫إلى‬ ‫الموارد‬ ‫المحددة‬ ‫بواسطة‬ ‫نظام‬ ‫التشغيل‬  Security – defense of the system against internal and external attacks ‫األمن‬ - ‫الدفاع‬ ‫عن‬ ‫النظام‬ ‫ضد‬ ‫الهجمات‬ ‫الداخلية‬ ‫والخارجية‬  Systems generally first distinguish among users, to determine who can do what • User identities (user IDs, security IDs) include name and associated number, one per user ‫تتضمن‬ ‫هويات‬ ‫المستخدم‬ ( ‫معرفات‬ ‫المستخدم‬ ‫ومعرفات‬ ‫األمان‬ ) ‫االسم‬ ‫والرقم‬ ‫المرتبط‬ ‫به‬ ، ‫واحد‬ ‫لكل‬ ‫مس‬ ‫تخدم‬ • User ID then associated with all files, processes of that user to determine access control ‫ثم‬ ‫يتم‬ ‫ربط‬ ‫معرف‬ ‫المستخدم‬ ‫بجميع‬ ‫الملفات‬ ، ‫وعمليات‬ ‫ذلك‬ ‫المستخدم‬ ‫لتحديد‬ ‫التحكم‬ ‫في‬ ‫الوصول‬ • Group identifier (group ID) allows set of users to be defined and controls managed, then also associated with each process, file ‫يسمح‬ ‫معرف‬ ‫المجموعة‬ ( ‫معرف‬ ‫المجموعة‬ ) ‫بتحديد‬ ‫مجموعة‬ ‫من‬ ‫المستخدمين‬ ‫وإدارة‬ ‫عناصر‬ ‫التحكم‬ ، ‫ثم‬ ‫ربط‬ ‫ها‬ ‫ا‬‫أيض‬ ‫بكل‬ ‫عملية‬ ‫أو‬ ‫ملف‬ 10/1/2022 45 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
The End 10/1/2022 46 OPERATING SYSTEMS– AL-NASSER UNIVERSITY

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2-OS - Operating-System Structures .pptx

  • 1. Operating Systems ‫التشغيل‬ ‫نظم‬ ‫رقم‬ ‫المحاضرة‬ 2 Operating-System Structures 10/1/2022 1 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 2. Agenda  Computer-System Organization • Interrupt • Storage Structure • I/O Structure  Computer-System Architecture • Single-Processor • Multi-Processors • Clustered System  Operating-System Operations • Multi-Programming and Multi-Tasking • Dual Mode  Resource Management • Process Management • Memory Management • Storage Management • Protection and Security 10/1/2022 2 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 4. Computer System Structure  Computer system can be divided into four components: • Hardware – provides basic computing resources • CPU, memory, I/O devices • Operating system • Controls and coordinates use of hardware among various applications and users • Application programs – define the ways in which the system resources are used to solve the computing problems of the users • Word processors, compilers, web browsers, database systems, video games • Users • People, machines, other computers 10/1/2022 4 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 5. Computer System  “The one program running at all times on the computer” is the kernel.  Everything else is either • a system program (ships with the operating system) , or • an application program. 10/1/2022 5 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 6. Computer Startup  Bootstrap program is loaded at power-up or reboot • Typically stored in ROM or EPROM, generally known as firmware • Initializes all aspects of system • Loads operating system kernel and starts execution 10/1/2022 6 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 7. Computer System Organization  Computer-system operation • One or more CPUs, device controllers connect through common bus providing access to shared memory • Concurrent execution of CPUs and devices competing for memory cycles 10/1/2022 7 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 8. Computer-System Operation  I/O devices and the CPU can execute concurrently ‫اجهزة‬ ‫االدخال‬ ‫واالخراج‬ ‫والمعالج‬ ‫يمكن‬ ‫ان‬ ‫تنفذ‬ ‫بالتزامن‬  Each device controller is in charge of a particular device type ‫كل‬ ‫متحكم‬ ‫مخصص‬ ‫لنوع‬ ‫معين‬ ‫من‬ ‫االجهزة‬  Each device controller has a local buffer ‫كل‬ ‫متحكم‬ ‫له‬ ‫مخزن‬ ‫داخلي‬  CPU moves data from/to main memory to/from local buffers ‫المعالج‬ ‫ينقل‬ ‫البيانات‬ ‫من‬ ‫والى‬ ‫الذاكرة‬ ‫من‬ ‫والى‬ ‫المخزن‬ ‫الداخلي‬  Device controller informs CPU that it has finished its operation by causing an interrupt ‫المتحكم‬ ‫يعلم‬ ‫المعالج‬ ‫بانتهاء‬ ‫عمله‬ ‫باستحداث‬ ‫قاطع‬ 10/1/2022 8 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 9. Common Functions of Interrupts  The occurrence of an event is usually signaled by an interrupt from either the hardware or the software. ‫ظهور‬ ‫حدث‬ ‫عادة‬ ‫يشار‬ ‫اليه‬ ‫بالمقاطعة‬ ‫سواء‬ ‫من‬ ‫الهاردوير‬ ‫او‬ ‫السوفتوير‬  Hardware may trigger an interrupt at any time by sending a signal to the CPU, usually by way of the system bus. ‫قد‬ ‫تتسبب‬ ‫األجهزة‬ ‫في‬ ‫حدوث‬ ‫مقاطعة‬ ‫في‬ ‫أي‬ ‫وقت‬ ‫عن‬ ‫طريق‬ ‫إرسال‬ ‫إشارة‬ ‫إلى‬ ‫وحدة‬ ‫المعالجة‬ ‫المركزية‬ ، ً ‫عادة‬ ‫عن‬ ‫طريق‬ ‫ناقل‬ ‫النظام‬ .  Software may trigger an interrupt by executing a special operation called a system call (also called a monitor call).  ‫قد‬ ‫يتسبب‬ ‫البرنامج‬ ‫في‬ ‫حدوث‬ ‫مقاطعة‬ ‫عن‬ ‫طريق‬ ‫تنفيذ‬ ‫عملية‬ ‫خاصة‬ ‫تسمى‬ ‫ا‬ ‫ستدعاء‬ ‫النظام‬ ( ‫تسمى‬ ‫ا‬‫أيض‬ ‫مكالمة‬ ‫الشاشة‬ ) . 10/1/2022 9 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 10. Common Functions of Interrupts  Interrupts are an important part of a computer architecture. ‫المقاطعات‬ ‫هي‬ ‫جزء‬ ‫مهم‬ ‫من‬ ‫معمارية‬ ‫الكمبيوتر‬ .  Each computer design has its own interrupt mechanism, but several functions are common. ‫كل‬ ‫تصميم‬ ‫كمبيوتر‬ ‫له‬ ‫آليه‬ ‫المقاطعة‬ ‫الخاصة‬ ‫به‬ ، ‫ولكن‬ ‫هناك‬ ‫العديد‬ ‫من‬ ‫الوظائف‬ ‫الشائعة‬ .  Interrupt transfers control to the interrupt service routine generally, through the interrupt vector, which contains the addresses of all the service routines ‫تنقل‬ ‫المقاطعة‬ ‫التحكم‬ ‫إلى‬ ‫روتين‬ ‫خدمة‬ ‫المقاطعة‬ ‫بشكل‬ ‫عام‬ ، ‫من‬ ‫خالل‬ ‫ناقل‬ ‫المقاطعة‬ ، ‫الذي‬ ‫يحتوي‬ ‫على‬ ‫عناو‬ ‫ين‬ ‫جميع‬ ‫إجراءات‬ ‫الخدمة‬  Interrupt architecture must save the address of the interrupted instruction ‫يجب‬ ‫أن‬ ‫تحفظ‬ ‫بنية‬ ‫المقاطعة‬ ‫عنوان‬ ‫التعليمات‬ ‫التي‬ ‫تمت‬ ‫مقاطعتها‬ .  A trap or exception is a software-generated interrupt caused either by an error or a user request ‫االعتراض‬ ‫أو‬ ‫االستثناء‬ ‫هو‬ ‫مقاطعة‬ ‫ينتج‬ ‫عن‬ ‫البرامج‬ ‫إما‬ ‫عن‬ ‫حدوث‬ ‫خطأ‬ ‫أو‬ ‫طلب‬ ‫مستخدم‬  An operating system is interrupt driven ‫نظام‬ ‫التشغيل‬ ‫هو‬ ‫معتمد‬ ‫على‬ ‫المقاطعة‬ 10/1/2022 10 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 11. Interrupt Handling  The operating system preserves the state of the CPU by storing registers and the program counter ‫يحافظ‬ ‫نظام‬ ‫التشغيل‬ ‫على‬ ‫حالة‬ ‫المعالج‬ ‫من‬ ‫خالل‬ ‫تخزين‬ ‫الس‬ ‫جالت‬ ‫وعداد‬ ‫البرنامج‬ .  Separate segments of code determine what action should be taken for each type of interrupt ‫تعليمات‬ ‫برمجية‬ ‫منفصلة‬ ‫تحدد‬ ‫اإلجراء‬ ‫الذي‬ ‫يجب‬ ‫اتخاذه‬ ‫لك‬ ‫ل‬ ‫نوع‬ ‫من‬ ‫أنواع‬ ‫المقاطعة‬ 10/1/2022 11 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 12. Interrupt Timeline 10/1/2022 12 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 13. STORAGE STRUCTURE 10/1/2022 13 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 14. Storage Structure  Main memory – only large storage media that the CPU can access directly ‫الذاكرة‬ ‫الرئيسية‬ : ‫وسيط‬ ‫تخزين‬ ‫يستطيع‬ ‫المعالج‬ ‫الوصول‬ ‫اليه‬ ‫مباشرة‬ • Random access • Typically volatile  Secondary storage – extension of main memory that provides large nonvolatile storage capacity ‫الذاكرة‬ ‫الثانوية‬ : ‫امتداد‬ ‫للذاكرة‬ ‫الرئيسية‬ ‫ولها‬ ‫سعة‬ ‫عالية‬ ‫غير‬ ‫متطايرة‬  Hard disks – rigid metal or glass platters covered with magnetic recording material • Disk surface is logically divided into tracks, which are subdivided into sectors • The disk controller determines the logical interaction between the device and the computer  Solid-state disks – faster than hard disks, nonvolatile • Various technologies • Becoming more popular 10/1/2022 14 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 15. Storage Hierarchy  Storage systems organized in hierarchy • Speed • Cost • Volatility  Caching – copying information into faster storage system; main memory can be viewed as a cache for secondary storage  Device Driver for each device controller to manage I/O • Provides uniform interface between controller and kernel 10/1/2022 15 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 16. Storage-Device Hierarchy 10/1/2022 16 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 17. PC Structure - Memory Hierarchy  ‫تتكونًهرميةًالذاكرةًمنًالتالي‬ : • ً‫المسجالت‬ registers • ً‫الذاكرةًالمخبأة‬ ) ‫الكاش‬ ( cache • ً‫الذاكرةًالرئيسية‬ ) ‫الرام‬ ( main memory • ًٍ‫الذاكرةًالثانوية‬ Secondary Memory 10/1/2022 17 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 18. PC Structure - Memory Hierarchy 10/1/2022 18 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 19. PC Structure - Memory Hierarchy  ً‫هنالكًعواملًتؤثرًفيًهرميةًالذاكرةًهي‬ : • ‫التطاير‬ volatility • ‫السرعة‬ Speed • ‫السعة‬ Capacity • ‫السعر‬ Price 10/1/2022 19 ‫التطاير‬ ‫زيادة‬ OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 20. PC Structure - Memory 10/1/2022 20 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 21. Caching  Important principle, performed at many levels in a computer (in hardware, operating system, software) ‫مصطلح‬ ‫مهم‬ ‫يوجد‬ ‫في‬ ‫اكثر‬ ‫من‬ ‫مستوى‬ ‫في‬ ‫الكمبيوتر‬  Information in use copied from slower to faster storage temporarily ‫المعلومات‬ ‫المستخدمة‬ ‫تنسخ‬ ‫من‬ ‫التخزين‬ ‫االبطا‬ ‫الى‬ ‫االسرع‬ ‫موقتا‬  Faster storage (cache) checked first to determine if information is there • If it is, information used directly from the cache (fast) • If not, data copied to cache and used there  Cache smaller than storage being cached • Cache management important design problem • Cache size and replacement policy 10/1/2022 21 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 22. I/O STRUCTURE 10/1/2022 22 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 23. Direct Memory Access Structure  Used for high-speed I/O devices able to transmit information at close to memory speeds  Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention  Only one interrupt is generated per block, rather than the one interrupt per byte 10/1/2022 23 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 24. A von Neumann architecture How a Modern Computer Works 10/1/2022 24 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 26. Computer-System Architecture  Most systems use a single general-purpose processor • Most systems have special-purpose processors as well  Multiprocessors systems growing in use and importance • Also known as parallel systems, tightly-coupled systems • Advantages include: • Increased throughput • Economy of scale • Increased reliability – graceful degradation or fault tolerance • Two types: • Asymmetric Multiprocessing – each processor is assigned a specific task. • Symmetric Multiprocessing – each processor performs all tasks 10/1/2022 26 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 27. Symmetric Multiprocessing Architecture 10/1/2022 27 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 28. A Dual-Core Design 10/1/2022 28 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 29. Clustered Systems  Like multiprocessor systems, but multiple systems working together • Usually sharing storage via a storage-area network (SAN) • Provides a high-availability service which survives failures •Asymmetric clustering has one machine in hot-standby mode •Symmetric clustering has multiple nodes running applications, monitoring each other • Some clusters are for high-performance computing (HPC) •Applications must be written to use parallelization 10/1/2022 29 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 30. Clustered Systems 10/1/2022 30 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 32. Operating System Structure  Multiprogramming (Batch system) needed for efficiency • Single user cannot keep CPU and I/O devices busy at all times • Multiprogramming organizes jobs (code and data) so CPU always has one to execute • A subset of total jobs in system is kept in memory • One job selected and run via job scheduling • When it has to wait (for I/O for example), OS switches to another job  Timesharing (multitasking) is logical extension in which CPU switches jobs so frequently that users can interact with each job while it is running, creating interactive computing • Response time should be < 1 second • Each user has at least one program executing in memory process • If several jobs ready to run at the same time  CPU scheduling • If processes don’t fit in memory, swapping moves them in and out to run • Virtual memory allows execution of processes not completely in memory 10/1/2022 32 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 33. Operating-System Operations  Interrupt driven (hardware and software) • Hardware interrupt by one of the devices ‫مقاطعة‬ ‫الهاردوير‬ ‫تكون‬ ‫بواسطة‬ ‫احد‬ ‫االجهزة‬ • Software interrupt (exception or trap): • Software error (e.g., division by zero) ‫اخطاء‬ ‫البرامج‬ • Request for operating system service ‫طلب‬ ‫خدمة‬ ‫من‬ ‫نظام‬ ‫التشغيل‬ • Other process problems include infinite loop, processes modifying each other or the operating system ‫مشاكل‬ ‫العمليات‬ ‫االخرى‬ ‫المتضمنة‬ ‫التكرار‬ ‫الالنهائي‬ ، ‫تعديالت‬ ‫العمليات‬ ‫على‬ ‫بع‬ ‫ضها‬ ‫او‬ ‫على‬ ‫نظام‬ ‫التشغيل‬ 10/1/2022 33 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 34. Operating-System Operations  Dual-mode operation allows OS to protect itself and other system components. ‫يتيح‬ ‫التشغيل‬ ‫ثنائي‬ ‫الوضع‬ ‫لنظام‬ ‫التشغيل‬ ‫حماية‬ ‫نفسه‬ ‫ومكونات‬ ‫النظام‬ ‫األخرى‬ . • User mode and kernel mode ‫وضع‬ ‫المستخدم‬ ‫ووضع‬ ‫النواة‬ . • Mode bit provided by hardware ‫يتم‬ ‫توفير‬ ‫بت‬ ‫الوضع‬ ‫بواسطة‬ ‫األجهزة‬ • Provides ability to distinguish when system is running user code or kernel code ‫يوفر‬ ‫القدرة‬ ‫على‬ ‫التمييز‬ ‫اذا‬ ‫كان‬ ‫النظام‬ ‫في‬ ‫طور‬ ‫تشغيل‬ ‫كود‬ ‫المستخدم‬ ‫أو‬ ‫كود‬ ‫النواة‬ • Some instructions designated as privileged, only executable in kernel mode ‫بعض‬ ‫التعليمات‬ ‫المصنفة‬ ‫على‬ ‫أنها‬ ‫ذات‬ ‫امتياز‬ ، ‫قابلة‬ ‫للتنفيذ‬ ‫فقط‬ ‫في‬ ‫وضع‬ ‫النواة‬ • System call changes mode to kernel, return from call resets it to user ‫استدعاء‬ ‫النظام‬ ‫يغيرالوضع‬ ‫إلى‬ ‫النواة‬ ، ‫والعودة‬ ‫من‬ ‫االستدعاء‬ ‫يعين‬ ‫الوضع‬ ‫إلى‬ ‫المستخدم‬ 10/1/2022 34 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 35. Transition from User to Kernel Mode  Timer to prevent infinite loop / process hogging resources • Timer is set to interrupt the computer after some time period ‫ضبط‬ ‫المؤقت‬ ‫على‬ ‫مقاطعة‬ ‫الكمبيوتر‬ ‫بعد‬ ‫فترة‬ ‫زمنية‬ . • Keep a counter that is decremented by the physical clock. ‫االحتفاظ‬ ‫بعداد‬ ‫يتناقص‬ ‫بواسطة‬ ‫الساعة‬ ‫الفعلية‬ . • Operating system set the counter. ‫نظام‬ ‫التشغيل‬ ‫يضبط‬ ‫العداد‬ • When counter zero generate an interrupt ‫عندما‬ ‫يكون‬ ‫العداد‬ ‫صفر‬ ‫يتم‬ ‫انشاء‬ ‫المقاطعة‬ • Set up before scheduling process to regain control or terminate program that exceeds allotted time ‫التهيئة‬ ‫قبل‬ ‫جدولة‬ ‫العملية‬ ‫الستعادة‬ ‫التحكم‬ ‫أو‬ ‫إنهاء‬ ‫البرنامج‬ ‫الذي‬ ‫تجاوز‬ ‫الوقت‬ ‫المخص‬ ‫ص‬ 10/1/2022 35 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 36. Transition from User to Kernel Mode 10/1/2022 36 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 37. RESOURCE MANAGEMENT 10/1/2022 37 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 38. Process Management  A process is a program in execution. It is a unit of work within the system. Program is a passive entity, process is an active entity. ‫العملية‬ ‫عبارة‬ ‫عن‬ ‫برنامج‬ ‫قيد‬ ‫التنفيذ‬ . ‫إنها‬ ‫وحدة‬ ‫عمل‬ ‫داخل‬ ‫النظام‬ ، ‫البرنامج‬ ‫كيان‬ ‫غير‬ ‫فعال‬ ، ‫والعملية‬ ‫كيان‬ ‫نشط‬ .  Process needs resources to accomplish its task • CPU, memory, I/O, files • Initialization data  Process termination requires reclaim of any reusable resources ‫يتطلب‬ ‫إنهاء‬ ‫العملية‬ ‫استعادة‬ ‫أي‬ ‫موارد‬ ‫قابلة‬ ‫إلعادة‬ ‫االستخدام‬  Single-threaded process has one program counter specifying location of next instruction to execute ‫تحتوي‬ ‫العملية‬ ‫أحادية‬ ‫الخيوط‬ ‫على‬ ‫عداد‬ ‫برنامج‬ ‫واحد‬ ‫يحدد‬ ‫موقع‬ ‫التعليمات‬ ‫التالية‬ ‫للتنف‬ ‫يذ‬ • Process executes instructions sequentially, one at a time, until completion ‫تنفذ‬ ‫العملية‬ ‫التعليمات‬ ‫بالتتابع‬ ، ‫ا‬‫واحد‬ ‫تلو‬ ‫اآلخر‬ ، ‫حتى‬ ‫اكتمالها‬ 10/1/2022 38 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 39. Process Management  Multi-threaded process has one program counter per thread ‫تحتوي‬ ‫العملية‬ ‫متعددة‬ ‫الخيوط‬ ‫على‬ ‫عداد‬ ‫برنامج‬ ‫واحد‬ ‫لكل‬ ‫خيط‬  Typically system has many processes, some user, some operating system running concurrently on one or more CPUs ً ‫عادة‬ ‫ما‬ ‫يحتوي‬ ‫النظام‬ ‫على‬ ‫العديد‬ ‫من‬ ‫العمليات‬ ، ‫بعضها‬ ‫للمستخدم‬ ، ‫وبعضها‬ ‫لنظام‬ ‫التشغيل‬ ‫تعمل‬ ‫ب‬ ‫شكل‬ ‫متزامن‬ ‫في‬ ‫معالج‬ ‫واحد‬ ‫أو‬ ‫أكثر‬ • Concurrency by multiplexing the CPUs among the processes / threads ‫التزامن‬ ‫عن‬ ‫طريق‬ ‫تنقل‬ ‫المعالج‬ ‫بين‬ ‫العمليات‬ / ‫الخيوط‬  The operating system is responsible for the following activities in connection with process management: • Creating and deleting both user and system processes ‫انشاء‬ ‫او‬ ‫حذف‬ ‫العمليات‬ • Suspending and resuming processes ‫تعليق‬ ‫واستئناف‬ ‫العمليات‬ • Providing mechanisms for process synchronization ‫توفير‬ ‫آليات‬ ‫لمزامنة‬ ‫العملية‬ • Providing mechanisms for process communication ‫توفير‬ ‫آليات‬ ‫لعملية‬ ‫االتصال‬ • Providing mechanisms for deadlock handling ‫توفير‬ ‫آليات‬ ‫للتعامل‬ ‫مع‬ ‫الطريق‬ ‫المسدود‬ 10/1/2022 39 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 40. Memory Management  To execute a program all (or part) of the instructions must be in memory ‫لتنفيذ‬ ‫برنامج‬ ، ‫يجب‬ ‫أن‬ ‫تكون‬ ‫جميع‬ ‫التعليمات‬ ( ‫أو‬ ‫جزء‬ ‫منها‬ ) ‫في‬ ‫الذاكرة‬ .  All (or part) of the data that is needed by the program must be in memory. ‫يجب‬ ‫أن‬ ‫تكون‬ ‫جميع‬ ( ‫أو‬ ‫جزء‬ ) ‫البيانات‬ ‫التي‬ ‫يحتاجها‬ ‫البرنامج‬ ‫في‬ ‫الذاكرة‬ .  Memory management determines what is in memory and when ‫تحدد‬ ‫إدارة‬ ‫الذاكرة‬ ‫ما‬ ‫هو‬ ‫موجود‬ ‫في‬ ‫الذاكرة‬ ‫ومتى‬ • Optimizing CPU utilization and computer response to users ‫تحسين‬ ‫استخدام‬ ‫وحدة‬ ‫المعالجة‬ ‫المركزية‬ ‫واستجابة‬ ‫الكمبيوتر‬ ‫للمستخدمين‬  Memory management activities • Keeping track of which parts of memory are currently being used and by whom ‫تتبع‬ ‫أي‬ ‫أجزاء‬ ‫من‬ ‫الذاكرة‬ ‫يتم‬ ‫استخدامها‬ ‫ا‬‫حالي‬ ‫ومن‬ ‫قبل‬ ‫من‬ • Deciding which processes (or parts thereof) and data to move into and out of memory ‫تحديد‬ ‫العمليات‬ ( ‫أو‬ ‫أجزاء‬ ‫منها‬ ) ‫والبيانات‬ ‫التي‬ ‫سيتم‬ ‫نقلها‬ ‫إلى‬ ‫الذاكرة‬ ‫وخارجها‬ • Allocating and deallocating memory space as needed ‫تخصيص‬ ‫مساحة‬ ‫الذاكرة‬ ‫وإلغاء‬ ‫تخصيصها‬ ‫حسب‬ ‫الحاجة‬ 10/1/2022 40 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 41. Storage Management  OS provides uniform, logical view of information storage ‫يوفر‬ ‫نظام‬ ‫التشغيل‬ ‫رؤية‬ ‫موحدة‬ ‫ومنطقية‬ ‫لتخزين‬ ‫المعلومات‬ • Abstracts physical properties to logical storage unit - file ‫يلخص‬ ‫الخصائص‬ ‫الفيزيائية‬ ‫لوحدة‬ ‫التخزين‬ ‫المنطقية‬ - ‫الملف‬ • Each medium is controlled by device (i.e., disk drive, tape drive) ‫يتم‬ ‫التحكم‬ ‫في‬ ‫كل‬ ‫وسيط‬ ‫بواسطة‬ ‫جهاز‬ ( ‫أي‬ ‫محرك‬ ‫األقراص‬ ‫ومحرك‬ ‫الشريط‬ ) •Varying properties include access speed, capacity, data- transfer rate, access method (sequential or random) ‫تشمل‬ ‫الخصائص‬ ‫المتغيرة‬ ‫سرعة‬ ‫الوصول‬ ، ‫والسعة‬ ، ‫ومعدل‬ ‫نقل‬ ‫البيانا‬ ‫ت‬ ، ‫وطريقة‬ ‫الوصول‬ ( ‫تسلسلي‬ ‫أو‬ ‫عشوائي‬ ) 10/1/2022 41 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 42. Storage Management  File-System management • Files usually organized into directories ‫عادة‬ ‫ما‬ ‫يتم‬ ‫تنظيم‬ ‫الملفات‬ ‫في‬ ‫أدلة‬ • Access control on most systems to determine who can access what ‫التحكم‬ ‫في‬ ‫الوصول‬ ‫إلى‬ ‫معظم‬ ‫األنظمة‬ ‫لتحديد‬ ‫من‬ ‫يمكنه‬ ‫الوصول‬ ‫إلى‬ ‫ماذا‬ • OS activities include • Creating and deleting files and directories ‫إنشاء‬ ‫وحذف‬ ‫الملفات‬ ‫واألدلة‬ • Primitives to manipulate files and directories ‫األساسيات‬ ‫لمعالجة‬ ‫الملفات‬ ‫واألدلة‬ • Mapping files onto secondary storage ‫تعيين‬ ‫الملفات‬ ‫على‬ ‫التخزين‬ ‫الثانوي‬ • Backup files onto stable (non-volatile) storage media ‫النسخ‬ ‫االحتياطي‬ ‫للملفات‬ ‫على‬ ‫وسائط‬ ‫تخزين‬ ‫مستقرة‬ ( ‫غير‬ ‫متطايرة‬ ) 10/1/2022 42 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 43. Mass-Storage Management  Usually disks used to store data that does not fit in main memory or data that must be kept for a “long” period of time ‫عادة‬ ‫األقراص‬ ‫المستخدمة‬ ‫لتخزين‬ ‫البيانات‬ ‫التي‬ ‫تتسع‬ ‫في‬ ‫الذاكرة‬ ‫الرئيسية‬ ‫أو‬ ‫البيانات‬ ‫التي‬ ‫يجب‬ ‫االحتفاظ‬ ‫بها‬ ‫لف‬ ‫ترة‬ " ‫طويلة‬ " ‫من‬ ‫الوقت‬  Proper management is of central importance ‫اإلدارة‬ ‫السليمة‬ ‫لها‬ ‫أهمية‬ ‫مركزية‬  OS activities • Free-space management ‫إدارة‬ ‫المساحة‬ ‫الخالية‬ • Storage allocation ‫تخصيص‬ ‫التخزين‬ • Disk scheduling ‫جدولة‬ ‫القرص‬ • Partitioning ‫التجزئة‬ • Protection ‫الحماية‬ 10/1/2022 43 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 44. I/O Subsystem  One purpose of OS is to hide peculiarities of hardware devices from the user ‫يتمثل‬ ‫أحد‬ ‫أهداف‬ ‫نظام‬ ‫التشغيل‬ ‫في‬ ‫إخفاء‬ ‫خصائص‬ ‫األجهزة‬ ‫عن‬ ‫المستخدم‬  I/O subsystem responsible for • Memory management of I/O including buffering (storing data temporarily while it is being transferred), caching (storing parts of data in faster storage for performance), spooling (the overlapping of output of one job with input of other jobs) ‫ادارة‬ ‫الذاكرة‬ ‫لإلدخال‬ ‫واالخراج‬ ‫تتضمن‬ ‫التخزين‬ ‫المؤقت‬ ، ‫الذاكرة‬ ‫المخبأة‬ ، ‫المسالك‬ • General device-driver interface ‫واجهة‬ ‫برنامج‬ ‫تشغيل‬ ‫الجهاز‬ ‫العامة‬ • Drivers for specific hardware devices ‫التعريفات‬ ‫ألجهزة‬ ‫معينة‬ 10/1/2022 44 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 45. Protection and Security  Protection – any mechanism for controlling access of processes or users to resources defined by the OS ‫الحماية‬ – ‫هي‬ ‫أي‬ ‫آلية‬ ‫للتحكم‬ ‫في‬ ‫وصول‬ ‫العمليات‬ ‫أو‬ ‫المستخدمين‬ ‫إلى‬ ‫الموارد‬ ‫المحددة‬ ‫بواسطة‬ ‫نظام‬ ‫التشغيل‬  Security – defense of the system against internal and external attacks ‫األمن‬ - ‫الدفاع‬ ‫عن‬ ‫النظام‬ ‫ضد‬ ‫الهجمات‬ ‫الداخلية‬ ‫والخارجية‬  Systems generally first distinguish among users, to determine who can do what • User identities (user IDs, security IDs) include name and associated number, one per user ‫تتضمن‬ ‫هويات‬ ‫المستخدم‬ ( ‫معرفات‬ ‫المستخدم‬ ‫ومعرفات‬ ‫األمان‬ ) ‫االسم‬ ‫والرقم‬ ‫المرتبط‬ ‫به‬ ، ‫واحد‬ ‫لكل‬ ‫مس‬ ‫تخدم‬ • User ID then associated with all files, processes of that user to determine access control ‫ثم‬ ‫يتم‬ ‫ربط‬ ‫معرف‬ ‫المستخدم‬ ‫بجميع‬ ‫الملفات‬ ، ‫وعمليات‬ ‫ذلك‬ ‫المستخدم‬ ‫لتحديد‬ ‫التحكم‬ ‫في‬ ‫الوصول‬ • Group identifier (group ID) allows set of users to be defined and controls managed, then also associated with each process, file ‫يسمح‬ ‫معرف‬ ‫المجموعة‬ ( ‫معرف‬ ‫المجموعة‬ ) ‫بتحديد‬ ‫مجموعة‬ ‫من‬ ‫المستخدمين‬ ‫وإدارة‬ ‫عناصر‬ ‫التحكم‬ ، ‫ثم‬ ‫ربط‬ ‫ها‬ ‫ا‬‫أيض‬ ‫بكل‬ ‫عملية‬ ‫أو‬ ‫ملف‬ 10/1/2022 45 OPERATING SYSTEMS– AL-NASSER UNIVERSITY
  • 46. The End 10/1/2022 46 OPERATING SYSTEMS– AL-NASSER UNIVERSITY