What can cause page faults?

Page Fault. A page fault occurs when a program attempts to access a block of memory that is not stored in the physical memory, or RAM. The fault notifies the operating system that it must locate the data in virtual memory, then transfer it from the storage device, such as an HDD or SSD, to the system RAM.

What causes minor page faults?

A minor page fault occurs when a process needs data that is in memory and is assigned to another process. Minor page faults share memory pages between multiple processes – no additional data needs to be read from disk to memory.

How a page fault can be serviced if there is no free frame in the memory?

If no frames are free, the page replacement algorithm is run to remove a page. If frame selected is dirty, page is scheduled for transfer to disk, context switch takes place, fault process is suspended and another process is made to run until disk transfer is completed.

What happens when there is a page fault?

A page fault occurs when a program requests an address on a page that is not in the current set of memory resident pages. What happens when a page fault occurs is that the thread that experienced the page fault is put into a Wait state while the operating system finds the specific page on disk and restores it to physical memory.

When does a page fault occur in virtual memory?

Today, we’re going to take a look at one of the most common problems when dealing with virtual memory – the Page Fault. A page fault occurs when a program requests an address on a page that is not in the current set of memory resident pages.

What to do if virtual address causes page fault?

Once virtual address caused page fault is known, system checks to see if address is valid and checks if there is no protection access problem. If the virtual address is valid, the system checks to see if a page frame is free. If no frames are free, the page replacement algorithm is run to remove a page.

Why do I get demand zero page fault?

If you try to allocate a block from the heap and the heap manager allocates new pages, then accesses those pages, you’ll get a demand-zero page fault. If you try to hook a function in kernel32 by writing to kernel32’s pages, you’ll get a copy-on-write fault because those pages are silently being copied so your changes don’t affect other processes.