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37 Cards in this Set
- Front
- Back
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Process |
is a more than a program code which is sometimes known as the text sections |
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Program counter |
special register in the cpu that keeps track the memory addresses. It indicates the position of the current code which are the cpu are currently executing |
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Processors registers |
contents changes frequently as cpu changes instructions. Essential for performing arithmetic and logical operations. |
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Process stack |
which contains temporary data such as functions parameters, return addresses, and local variables. It includes data sections. Is a region of memory that is allocated for processing for managing data. Organized as LIFO (Last in first out) |
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1. Process stack 2. Data sections |
Region of memory |
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Data sections |
which contains the global variables. Typically contains a global and static variable |
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Heap |
is a memory that is dynamically allocated during process runtime. Is more flexible in memory allocation and reallocation. |
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Program |
is a passive entity - it is just a file containing a list of instructions stored(executable files) |
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Process |
is an active entity with a program counter specifying the next instructions to execute |
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1. New - process is being created 2. Running - the instructions are being executed 3. Waiting - waiting for an event to occur 4. Ready - process is waiting to be assigned to a processor. there is queue 5. Terminated - process is finished executing. |
Process states |
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process controller block (PCB) |
each process is represented in the operating system by a |
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process controller block (PCB) |
also called a task control block |
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process control block (PCB) |
Type of data structure that operating uses to manage and track information about each process that is running in our computer system. It serves as a blueprint for operating systems to manage and understand the state. |
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1. Process States 2. Program Counter 3. CPU Registers 4. CPU Scheduling Information 5. Memory management information |
The PCB typically contains a variety of information about the process, including: __ |
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Process States |
maintain current information about the current state of the process |
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Program Counter |
is a type of register. considered as a register. since it is a memory, it stores the address of the next instructions that the cpu will execute. |
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CPU Scheduling Information |
contains details or informations that is related to cpu scheduling such as priority(scheduling algorithms, time spent executing) helps os to decide about which process to execute next based on scheduling criteria (fairness). |
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Memory management information |
based and limit registers specifying the range of the memory. other memory related data. |
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Process Scheduling |
activity of the process manager that handles the removal of the running process from the CPU and the selection of another process based on a particular strategy. Core activity of operating system process management |
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1. Non-preemptive 2. Preemptive |
Categories of Scheduling |
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Non-preemptive |
it is also known as cooperative scheduling |
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Non-preemptive |
It allows a process to keep the cpu until it voluntarily relinquish its control. |
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Preemptive |
the os assigns resources to a process for a predetermined period. The process switches from running state to ready state or from waiting for state to ready state during resource allocation. |
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Preemptive |
It can occur for various systems: Occurrence of event that requires immediate action. |
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1. Long Term or Job Scheduler 2. Short-Term or CPU Scheduler 3. Medium-Term Scheduler |
Types of Process Schedulers |
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Long Term or Job Scheduler |
it plays a very crucial role in managing the number of processes in ready state. It brings new process to the ‘Ready state’. It controls the Degree of Multi-programming |
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Short-Term or CPU Scheduler |
it is responsible for selecting one process from the ready state for scheduling it on the running state. |
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Medium-Term Scheduler- |
It is responsible for suspending and resuming process. It mainly does swapping |
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1.I/O Schedulers 2. Real-Time Schedulers |
Other Schedulers |
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I/O Schedulers |
re in charge of managing execution of I/O operations such as reading and writing to discs or networks FCFS (First-Come, First-Served) or RR (Round Robin). |
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Real-Time Schedulers |
ensure that critical tasks are completed within a specified time frame. EDF(Earliest Deadline First) or RM (Rate Monotonic) |
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1. Running 2. Not running |
Two-State Process Model Short-Term |
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Context Switching |
is a mechanism to store and restore the state or context of a CPU in the Process Control Block. |
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1. Job Queue 2. Ready queue 3. Device queue |
Process Scheduling Queues |
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Job Queue |
this queue keeps all the processes in the system. |
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Ready queue |
this queue keeps a set of all processes residing in main memory, read and waiting to execute. A new process is always put in this queue. |
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Device queue |
the processes which are blocked due to unavailability of an I/O device constitute this queue |
