Does Each Process Have Its Own Virtual Address Space?

Can two processes write to the same physical memory address?

2 diff process can have same virtual memory address.

This is because each process has its own page table.

Each process thinks it as 4Gb memory on a 32-bit machine.

So both P1 and P2 can access address 0xabcdef – but the physical memory location might be different..

What are shared pages?

Sharing is another design issue for paging system. It is very common for many computer users to be running the same program at the same time in a large multiprogramming computer system. With shared pages, a problem occurs, whenever two or more than two processes (multiple processes) share some code. …

Can two processes have data at the same virtual address?

Disk A virtual address can be mapped to either physical memory or disk. Because different processes will have different mappings from virtual to physical addresses, two programs can freely use the same virtual address.

Why is it important that a process has its own address space?

One of the principal advantages of virtual memory is that each process has its own virtual address space, which is mapped to physical memory by the operating system. … For example, allocations for the kernel are satisfied immediately and are visible globally no matter what process is on the CPU.

How many types of address space are there?

three typesThe three types of address spaces are the ACB address space, the associated address space, and the session address space. These are defined in the following sections.

What is the difference between address space and memory space?

The hardware device called Memory-Management Unit is used for mapping logical address to its corresponding physical address. … The term Physical Address Space is used for all physical addresses corresponding to the logical addresses in a Logical address space.

Are threads faster than processes?

a process: because very little memory copying is required (just the thread stack), threads are faster to start than processes. … The CPU caches and program context can be maintained between threads in a process, rather than being reloaded as in the case of switching a CPU to a different process.

Does each thread have its own heap?

Each thread has its own stack and call stack. Each thread shares the same heap. It depends on what exactly you mean when saying “heap”. All threads share the address space, so heap-allocated objects are accessible from all threads.

What are included in the address space of a process?

The process address space consists of the linear address range presented to each process and, more importantly, the addresses within this space that the process is allowed to use. Each process is given a flat 32- or 64-bit address space, with the size depending on the architecture.

What do you think will happen if your address space size is bigger than your physical memory?

When a virtual address space is larger than the physical memory, OS can use swapping to evict page frames (e.g. LRU eviction). CPU generates Page Fault where then page that is in disk is swapped into the main memory.

How many threads can a process have?

A process can have anywhere from just one thread to many threads. When a process starts, it is assigned memory and resources.

Can two running processes share the complete process image in physical memory?

(b) Can two running processes share the complete process image in physical memory (not just parts of it)? Ans: (a) Yes, two processes can run the same program. … Consider a process executing on a CPU.

Can two processes share memory?

Yes, two processes can both attach to a shared memory segment. A shared memory segment wouldn’t be much use if that were not true, as that is the basic idea behind a shared memory segment – that’s why it’s one of several forms of IPC (inter-Process communication).

Does each process have a page table?

Each process has its own page table in the kernel. Having a separate page table for each process is necessary for process isolation as they should not be allowed to stomp on each others memory. Since each process has a different page table, there is not one pmap that will work for every process.

Where is virtual address space stored?

The virtual address space is kept in secondary storage (disk). The virtual part of virtual memory means that the operating system maintains an image of the address space in secondary storage. Because an image of the address space is kept in secondary storage, it can be larger than the physical memory.