Precedence Graph in Operating System Last Updated : 11 Oct, 2022 Summarize Comments Improve Suggest changes Share Like Article Like Report Prerequisite - Process Synchronization Precedence Graph is a directed acyclic graph which is used to show the execution level of several processes in operating system. It consists of nodes and edges. Nodes represent the processes and the edges represent the flow of execution. Properties of Precedence Graph : Following are the properties of Precedence Graph: It is a directed graph.It is an acyclic graph.Nodes of graph correspond to individual statements of program code.Edge between two nodes represents the execution order.A directed edge from node A to node B shows that statement A executes first and then Statement B executes. Consider the following code: S1 : a = x + y; S2 : b = z + 1; S3 : c = a - b; S4 : w = c + 1; If above code is executed concurrently, the following precedence relations exist: c = a - b cannot be executed before both a and b have been assigned values.w = c + 1 cannot be executed before the new values of c has been computed.The statements a = x + y and b = z + 1 could be executed concurrently. Example: Consider the following precedence relations of a program: S2 and S3 can be executed after S1 completes.S4 can be executed after S2 completes.S5 and S6 can be executed after S4 completes.S7 can be executed after S5, S6 and S3 complete. Solution: Comment More infoAdvertise with us Next Article Process Schedulers in Operating System P pp_pankaj Follow Improve Article Tags : Operating Systems GATE CS Process Synchronization Similar Reads Process Schedulers in Operating System A process is the instance of a computer program in execution. Scheduling is important in operating systems with multiprogramming as multiple processes might be eligible for running at a time.One of the key responsibilities of an Operating System (OS) is to decide which programs will execute on the C 7 min read Critical Regions in Operating System In an operating system, a critical region refers to a section of code or a data structure that must be accessed exclusively by one method or thread at a time. Critical regions are utilized to prevent concurrent entry to shared sources, along with variables, information structures, or devices, that a 3 min read Multi Processing Operating System The operating system functions like a manager of all the available resources. Therefore operating system is defined as an interface between the system and the user. There are various types of operating systems such as Batch Operating Systems, Multi-programming Operating Systems, distributed operatin 4 min read I/O scheduling in Operating Systems Input/Output (I/O) operations are how a computer communicates with external devices such as hard drives, keyboards, printers, and network interfaces. These operations involve transferring data into and out of the system whether it’s reading a file, saving a document, printing, or sending data over a 6 min read Priority Scheduling in Operating System Priority scheduling is one of the most common scheduling algorithms used by the operating system to schedule processes based on their priority. Each process is assigned a priority value based on criteria such as memory requirements, time requirements, other resource needs, or the ratio of average I/ 4 min read List scheduling in Operating System Prerequisite - CPU Scheduling List Scheduling also known as Priority List Based Scheduling is a scheduling technique in which an ordered list of processes are made by assigning them some priorities. So, basically what happens is, a list of processes that are ready to be executed at a given point is 3 min read Like