Tirgul 4

Question 1

Do threads share a heap?

Answer 1

Yes

Question 2

Do threads share a stack?

Answer 2

No, every thread has its own stack

Question 3

In kernel level threads, where are the thread descriptors stored?

Answer 3

In the PCB. The PCB has holds pointers to all of the thread descriptions that the process has.

Question 4

In user level threads, where are the thread descriptors stored?

Answer 4

Inside the heap.

Question 5

Processes vs. Kernel Threads vs. User Threads:

Interactions between instances

Answer 5

Processes: protected from each other, require the OS to communicate

Kernel and User Threads: Share address space, simple communication

Question 6

Processes vs. Kernel Threads vs. User Threads:

Context switch overhead

Answer 6

Processes: High overhead, since all operations require a kernel trap, significant work.
Kernel Threads: medium overhead. Operations require kernel trap but little work.

User Threads: Low overhead, everything is done at user level