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Is there one stack per process when user level threads are used?

In both kernel and User level they have one stack per thread


What are the circumstances of user level thread better than kernel level thread?

There are two distinct models of thread controls, and they are user-level threads and kernel-level threads. The thread function library to implement user-level threads usually runs on top of the system in user mode. Thus, these threads within a process are invisible to the operating system. User-level threads have extremely low overhead, and can achieve high performance in computation. However, using the blocking system calls like read(), the entire process would block. Also, the scheduling control by the thread runtime system may cause some threads to gain exclusive access to the CPU and prevent other threads from obtaining the CPU. Finally, access to multiple processors is not guaranteed since the operating system is not aware of existence of these types of threads. On the other hand, kernel-level threads will guarantee multiple processor access but the computing performance is lower than user-level threads due to load on the system. The synchronization and sharing resources among threads are still less expensive than multiple-process model, but more expensive than user-level threads. Thus, user-level thread is better than kernel level thread.


Describe the action taken by a thread library to context switch between user level threads?

AnswerThe thread library function performs the following actions to context switch between user level threads:1. Copy all live registers to Thread control Block (TCB)2. Restore the state of the thread to run next i.e. (copy the values of live registers from (TCB) to registers)3. Move to the next thread to execute


What are user level threads?

•No special support needed from the kernel (use any Unix) •Thread creation and context switch are fast (no syscall) •Defines its own thread model and scheduling policies


Difference between Java threads and user level thread?

A Java thread can be considered as similar to a user level thread. Let us say you are running a web browser, windows media player and GTalk for chat simultaneously - Actually the operating system is running an individual thread for each of these apps which gives you a seamless feeling of things running in parallel. Similarly Java Threads are features in the Java programming language that allow you to run multiple JVM tasks in parallel.


What is the difference between Kernel and User level thread?

A kernel thread, sometimes called a LWP (Lightweight Process) is created and scheduled by the kernel. Kernel threads are often more expensive to create than user threads and the system calls to directly create kernel threads are very platform specific. A user thread is normally created by a threading library and scheduling is managed by the threading library itself (Which runs in user mode). All user threads belong to process that created them. The advantage of user threads is that they are portable. The major difference can be seen when using multiprocessor systems, user threads completely managed by the threading library can't be ran in parallel on the different CPUs, although this means they will run fine on uniprocessor systems. Since kernel threads use the kernel scheduler, different kernel threads can run on different CPUs. Many systems implement threading differently, A many-to-one threading model maps many user processes directly to one kernel thread, the kernel thread can be thought of as the main process. A one-to-one threading model maps each user thread directly to one kernel thread, this model allows parallel processing on the multiprocessor systems. Each kernel thread can be thought of as a VP (Virtual Process) which is managed by the scheduler.


What are the advantages and disadvantages of user level threads and kernel level threads?

User-level threads have the advantage of being lightweight and can be managed without kernel intervention, allowing for faster thread switching. However, they are limited in their ability to utilize multiple processors efficiently and can be blocked by system calls made by a single thread. Kernel-level threads, on the other hand, offer better performance on multi-core systems and can take advantage of kernel features, but they are heavier in terms of resource consumption and switching between threads can be slower due to kernel involvement.


What takes longer a context switch with user level threads or one with kernel level threads?

Kernel level threads take a longer time to context switch since OS will have to save and reload each and every TCB (Thread Control block) where as in user level no kernel intervention threads simply context switch more efficiently. But there are disadvantages such as since OS sees the user leve threads as a whole process it will not give a large portion of CPU time for execution if a thread is blocked the whole process goes to the waiting state please correct my answer if im wrong godlovesu49@hotmail.com thanks regards yo


Is main method a thread?

No, Main is not a daemon thread in Java. its a non daemon or user thread. Also any thread stem from Main will be non daemon because daemon is derived from parent Thread status.


Different types of threads in OS?

There are many different thread forms in use today. The most common are; BPV thread API thread profile gauge Thread profile gauge API 5b thread gauges API thread gauges Pipe thread gauges API Thread Gauge Manufacturer & Supplier Ring gauge use Pipe threader Acme thread Feeler gauge set Ring gauge set threaded pipe plug step gauge NPT thread gauge Tapered pipe thread


What are cheats to thread words level 7?

Unfortunately, for the game Thread Words and for any level including level 7, there are no cheats. You have to answer the question correctly in order to move onto the next level.


What is user thread?

A thread can be loosely defined as a separate stream of execution that takes place simultaneously with and independently of everything else that might be happening.