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 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
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?
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.
What is Dispatcher?
Dispatcher module gives control of the CPU to the process selected by the short-term scheduler; this involves: Switching context, Switching to user mode, Jumping to the proper location in the user program to restart that program, dispatch latency time it takes for the dispatcher to stop one process and start another running.
What is CPU Scheduler?
Selects from among the processes in memory that are ready to execute, and allocates the CPU to one of them.
What is Context Switch?
Switching the CPU to another process requires saving the state of the old process and loading the saved state for the new process. This task is known as a context switch. Context-switch time is pure overhead, because the system does no useful work while switching.
What is cache memory?
Cache memory is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data from larger memory.
What is a Safe State and what is its use in deadlock avoidance?
When a process requests an available resource, system must decide if immediate allocation leaves the system in a safe state. System is in safe state if there exists a safe sequence of all processes. Deadlock Avoidance: ensure that a system will never enter an unsafe state.
What is fragmentation? Different types of fragmentation?
Fragmentation occurs in a dynamic memory allocation system when many of the free blocks are too small to satisfy any request.
External Fragmentation
External Fragmentation happens when a dynamic memory allocation algorithm allocates some memory and a small piece is left over that cannot be effectively used. If too much external fragmentation occurs, the amount of usable memory is drastically reduced. Total memory space exists to satisfy a request, but it is not contiguous.
Internal Fragmentation
Internal fragmentation is the space wasted inside of allocated memory blocks because of restriction on the allowed sizes of allocated blocks. Allocated memory may be slightly larger than requested memory; this size difference is memory internal to a partition, but not being used
Read full article from Operating system questions | TechInterviews
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 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
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?
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.
What is Dispatcher?
Dispatcher module gives control of the CPU to the process selected by the short-term scheduler; this involves: Switching context, Switching to user mode, Jumping to the proper location in the user program to restart that program, dispatch latency time it takes for the dispatcher to stop one process and start another running.
What is CPU Scheduler?
Selects from among the processes in memory that are ready to execute, and allocates the CPU to one of them.
What is Context Switch?
Switching the CPU to another process requires saving the state of the old process and loading the saved state for the new process. This task is known as a context switch. Context-switch time is pure overhead, because the system does no useful work while switching.
What is cache memory?
Cache memory is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data from larger memory.
What is a Safe State and what is its use in deadlock avoidance?
When a process requests an available resource, system must decide if immediate allocation leaves the system in a safe state. System is in safe state if there exists a safe sequence of all processes. Deadlock Avoidance: ensure that a system will never enter an unsafe state.
What is fragmentation? Different types of fragmentation?
Fragmentation occurs in a dynamic memory allocation system when many of the free blocks are too small to satisfy any request.
External Fragmentation
External Fragmentation happens when a dynamic memory allocation algorithm allocates some memory and a small piece is left over that cannot be effectively used. If too much external fragmentation occurs, the amount of usable memory is drastically reduced. Total memory space exists to satisfy a request, but it is not contiguous.
Internal Fragmentation
Internal fragmentation is the space wasted inside of allocated memory blocks because of restriction on the allowed sizes of allocated blocks. Allocated memory may be slightly larger than requested memory; this size difference is memory internal to a partition, but not being used
No comments:
Post a Comment