A Computer Science portal for geeks. Complete Piano Chord Chart. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice. GjrxO-PDPdk/hqdefault.jpg' alt='C Program Round Robin Operating System' title='C Program Round Robin Operating System' />Operating System Process Management Introduction. Program vs Process. A process is a program in execution. For example, when we write a program in C or C and compile it, compiler creates a binary code. The original code and Binary code, both are programs. When we actually run the binary code, it becomes a process. A process is an active entity as oppose to program which considered to be a passive entity. A single program can create many processes when run multiple times, for example when we open an exe or binary file multiple times, many instances begin many processes are created. How Does a process looks in Memory Text Section Process is also sometime known as the Text Section. It also includes the current activity represented by the value of Program Counter. Stack Stack contains the temporary data such as function parameters, return address and local variables. Data Section Contains the global variable. Operating system, OS interview questions and answers Here are all possible Operating System interview questions with answers that might be asked during interview. I know you all are curious to know what is Real Time Operating System RTOS and How an RTOS works Here I explain basics of an RTOS with its functionalities. Developed in partnership with the worlds leading chip companies over a 12 year period, FreeRTOS is the market leading real time operating system or RTOS, and the. GHNXNMS1bfY/hqdefault.jpg' alt='C Program Round Robin Operating System' title='C Program Round Robin Operating System' />Heap Section Dynamically allocated memory to process during its run time. Refer this for more details of sections. Attributes or Characteristics of a Process. A process has following Attributes. Process Id A unique identifier assigned by operating system. Process State Can be ready, running,. C Program Round Robin Operating System' title='C Program Round Robin Operating System' />CPU registers Like Program Counter CPU registers must be saved and. CPU. 5. Accounts information 6. IO status information For example devices allocated to process. CPU scheduling information For example Priority Different processes. All the above attributes of a process are also known as Context of the process. Every Process has its known Program control BlockPCB i. PCB. All the Above Attributes are the part of the PCB. C Program Round Robin Operating System' title='C Program Round Robin Operating System' />States of Process A process is in one of the following states. New Newly Created Process or being created process. Ready After creation Process moves to Ready state, i. Run Currently running process in CPU only one process at. Wait or Block When process request for IO request. Complete or Terminated Process Completed its execution. Suspended Ready When ready queue becomes full, some processes. Suspended Block When waiting queue becomes full. Context Switching. Process of saving the context of one process and loading the context of other process is known as Context Switching. In simple term it is like loading and unloading of process from running state to ready state. When does Context switching happen When a high priority process comes to ready state, compared to priority of running process. Interrupt Occurs. User and Kernel mode switch It is not necessary though4. Preemptive CPU scheduling used. Context Switch vs Mode Switch. A mode switch occurs when CPU privilege level is changed, for example when a system call is made or a fault occurs. The kernel works in more privileged mode than a standard user task. If a user process wants to access things which are only accessible to kernel, a mode switch must occur. The currently executing process need not to be changed during a mode switch. A mode switch typically occurs for a process context switch to occur. Only the Kernel can cause a context switch. CPU Bound vs IO Bound Processes A CPU Bound Process requires more amount of CPU time or spends more time in the running state. IO Bound Process requires more amount of IO time and less CPU time. IO Bound process more time in the waiting state. Exercise 1. Which of the following need not necessarily be saved on a context switch between processesGATE CS 2. A General purpose registersB Translation look aside bufferC Program counterD All of the above. Answer BExplanation In a process context switch, the state of the first process must be saved somehow, so that, when the scheduler gets back to the execution of the first process, it can restore this state and continue. The state of the process includes all the registers that the process may be using, especially the program counter, plus any other operating system specific data that may be necessary. A Translation look aside buffer TLB is a CPU cache that memory management hardware uses to improve virtual address translation speed. A TLB has a fixed number of slots that contain page table entries, which map virtual addresses to physical addresses. On a context switch, some TLB entries can become invalid, since the virtual to physical mapping is different. The simplest strategy to deal with this is to completely flush the TLB. The time taken to switch between user and kernel modes of execution be t. Which of the following is TRUE GATE CS 2. A t. B t. 1 t. 2C t. D nothing can be said about the relation between t. Answer CExplanation Process switching involves mode switch. Context switching can occur only in kernel mode. Quiz on Process Management. References http www. Course. NotesOperating. Systems3Processes. G2. 2. 2. 25. 0 0. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.