Cpu scheduling & process synchronizing
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The document discusses CPU scheduling and process synchronization in operating systems. It covers the objectives of CPU scheduling, which are to maximize CPU utilization and keep processes running at all times. There are two types of CPU scheduling algorithms: preemptive and non-preemptive. Process synchronization is needed to share system resources and handle concurrent access to shared data to minimize inconsistent data. It addresses the critical section problem where processes need synchronized access to shared resources using conditions like mutual exclusion and bounded waiting.
Cpu scheduling & process synchronizing
- 1. Assignment: CPU Scheduling & process Synchronizing Submitted By: Usman Farooq Department: BSSE Semester 4th Submitted To: Sir Farhan Afro Assian Institute Affiliated with GCUF
- 2. CPU Scheduling and Algorithm Basic Concept: Main objective of multiprogramming is to keep on running processes all the time for maximum CPU utilization. Scheduling is fundamental function of OS. The task of selecting the processes in memory that are ready to execute, and allocating them to the CPU is performed by the CPU Scheduler. CPU Scheduler: Types of CPU Scheduler: There are two types of CPU Scheduler. 1-Prremptive 2- non-preemptive. 1-preemptive: Once a process is allocated the CPU, it does not leave unless: it has to wait, e.g., for I/O request it terminates 2-Non-preemptive: OS can force (preempt) a process from CPU at anytime E.g., to allocate CPU to another higher-priority process Scheduling Criteria:
- 3. CPU utilization: keep the CPU as busy as possible Maximize. Throughput: No of processes that complete their execution per time unit Maximize Turnaround time: amount of time to execute a particular process (time from submission to termination) Minimize Waiting time: amount of time a process has been waiting in the ready queue (sum of time waiting in ready queue) Minimize Response time: amount of time it takes from when a request was submitted until the first response is produced, not output (for time-sharing environment) Minimize Scheduling Algorithms: First Come, First Served Shortest Job First Priority Round Robin Implementation in C++: Source Code (.c) Compiler Executable Windows Micro Kernel Memory CPU
- 4. Process synchronizing in operating system Process Synchronization means sharing system resources by processes in a such a way that, Concurrent access to shared data is handled thereby minimizing the chance of inconsistent data. Maintaining data consistency demands mechanisms to ensure synchronized execution of cooperating processes. Race Condition: A race condition is an undesirable situation that occurs when a device or system attempts to perform two or more operations at the same time, but because of the nature of the device or system, the operations must be done in the proper sequence to be done correctly. • Threads are racing to access the data • Different ways race condition can happen: • Kernel preemption • Parallel processing Critical Condition: The critical section is a code segment where the shared variables can be accessed. An atomic action is required in a critical section i.e. only one process can execute in its critical section at a time. All the other processes have to wait to execute in their critical sections. Solution to the Critical Section Problem The critical section problem needs a solution to synchronize the different processes. The solution to the critical section problem must satisfy the following conditions − Mutual Exclusion Mutual exclusion implies that only one process can be inside the critical section at any time. If any other processes require the critical section, they must wait until it is free. Progress
- 5. Progress means that if a process is not using the critical section, then it should not stop any other process from accessing it. In other words, any process can enter a critical section if it is free. Bounded Waiting Bounded waiting means that each process must have a limited waiting time. Itt should not wait endlessly to access the critical section