Why do we need per process kernel stack?

Just like there has to be a separate place for each process to hold its set of saved registers (in its process table entry), each process also needs its own kernel stack, to work as its execution stack when it is executing in the kernel. Since threads can also do system calls, each needs a kernel stack as well.

Why do we need a separate stack per thread?

Explain. Each thread calls procedures on its own, so it must have its own stack for the local variables, return addresses, and so on. In this problem you are to compare reading a file using a single-threaded file server and a multithreaded server, running on a single-CPU machine.

Why do threads have a user and a kernel stack?

With separate user and kernel stacks for each process or thread, we have better isolation. Problems in the user stack can’t cause a crash in the kernel. This isolation makes the kernel more secure because it only trusts the stack area that is under its control.

Why does each LWP required a separate kernel stack?

In practice, many operating systems do not restrict the number of threads running kernel-level code. In fact, placing this restriction would seriously limit the scalability of the kernel. Without this restriction, multiple kernel stacks are required.

Why each process has 2 stacks?

There are 2 stacks because there are 2 CPU execution contexts. The user mode stack will cater to your program with respect to creating stack frames for functions, local variables, return addresses etc.

Can threads have multiple stacks?

1 Answer. Yes threads have their own stacks and their own kernel stacks (e.g. linux).

What is the advantage of implementing threads in the kernel?

Advantages of Kernel-Level Threads Multiple threads of the same process can be scheduled on different processors in kernel-level threads. The kernel routines can also be multithreaded. If a kernel-level thread is blocked, another thread of the same process can be scheduled by the kernel.

Why thread is lighter than process?

Threads are sometimes called lightweight processes because they have their own stack but can access shared data. Because threads share the same address space as the process and other threads within the process, the operational cost of communication between the threads is low, which is an advantage.