What are the basic functions of an operating system?
What resources are used when a thread created? How do they differ from those when a process is created?
What is Throughput, Turnaround time, waiting time and Response time?
Throughput: Number of processes that complete their execution per time unit. Turnaround Time: Amount of time to execute a particular process. Waiting Time: Amount of time a process has been waiting
in the ready queue. 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).
What is the state of the processor, when a process is waiting for some event to occur?
Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault. The system can detect thrashing by evaluating the level of CPU utilization as compared to the level of multiprogramming. It can be eliminated by reducing the level of multiprogramming.
Operating system controls and coordinates the use of the hardware among the various application programs for various uses. Operating system acts as resource allocator and manager. Since there are many possibly conflicting requests for resources, the operating system must decide which requests are allocated resources to operating the computer system efficiently and fairly. Also, operating system is control program which controls the user programs to prevent errors and improper use of the computer. It is especially concerned with the operation and control of I/O devices.
Why paging is used?
Paging is solution to external fragmentation problem which is to permit the logical address space of a process to be noncontiguous, thus allowing a process to be allocating physical memory wherever the latter is available.
What resources are used when a thread created? How do they differ from those when a process is created?
When a thread is created the threads does not require any new resources to execute the thread shares the resources like memory of the process to which they belong to. The benefit of code sharing is that it allows an application to have several different threads of activity all within the same address space. Whereas if a new process creation is very heavyweight because it always requires new address space to be created and even if they share the memory then the inter process communication is expensive when compared to the communication between the threads.
What is virtual memory?
Virtual memory is hardware technique where the system appears to have more memory that it actually does. This is done by time-sharing, the physical memory and storage parts of the memory one disk when they are not actively being used.
Virtual memory is hardware technique where the system appears to have more memory that it actually does. This is done by time-sharing, the physical memory and storage parts of the memory one disk when they are not actively being used.
What is Throughput, Turnaround time, waiting time and Response time?
Throughput: Number of processes that complete their execution per time unit. Turnaround Time: Amount of time to execute a particular process. Waiting Time: Amount of time a process has been waiting
in the ready queue. 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).
What is the state of the processor, when a process is waiting for some event to occur?
Waiting state
What is the important aspect of a real-time system or Mission Critical Systems?
A real time operating system has well defined fixed time constraints. Process must be done within the defined constraints or the system will fail. An example is the operating system for a flight control computer or an advanced jet airplane. Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems.
What are the types of Real Time System?
Real-Time systems may be either hard or soft real-time. Hard real-time: Secondary storage limited or absent, data stored in short term memory, or read-only memory (ROM), Conflicts with time-sharing systems, not supported by general-purpose operating systems.Soft real-time: Limited utility in industrial control of robotics, Useful in applications (multimedia, virtual reality) requiring advanced operating-system features.
What is the difference between Hard and Soft real-time systems?
A hard real-time system guarantees that critical tasks complete on time. This goal requires that all delays in the system be bounded from the retrieval of the stored data to the time that it takes the operating system to finish any request made of it. A soft real time system where a critical real-time task gets priority over other tasks and retains that priority until it completes. As in hard real time systems kernel delays need to be bounded.
What is the cause of thrashing? How does the system detect thrashing? Once it detects thrashing, what can the system do to eliminate this problem?A real time operating system has well defined fixed time constraints. Process must be done within the defined constraints or the system will fail. An example is the operating system for a flight control computer or an advanced jet airplane. Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems.
What are the types of Real Time System?
Real-Time systems may be either hard or soft real-time. Hard real-time: Secondary storage limited or absent, data stored in short term memory, or read-only memory (ROM), Conflicts with time-sharing systems, not supported by general-purpose operating systems.Soft real-time: Limited utility in industrial control of robotics, Useful in applications (multimedia, virtual reality) requiring advanced operating-system features.
What is the difference between Hard and Soft real-time systems?
A hard real-time system guarantees that critical tasks complete on time. This goal requires that all delays in the system be bounded from the retrieval of the stored data to the time that it takes the operating system to finish any request made of it. A soft real time system where a critical real-time task gets priority over other tasks and retains that priority until it completes. As in hard real time systems kernel delays need to be bounded.
Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault. The system can detect thrashing by evaluating the level of CPU utilization as compared to the level of multiprogramming. It can be eliminated by reducing the level of multiprogramming.
