Showing posts with label malloc( ). Show all posts
Showing posts with label malloc( ). Show all posts

Saturday, 5 November 2011

What is page thrashing?

Some operating systems (such as UNIX or Windows in enhanced mode) use virtual memory. Virtual memory is a technique for making a machine behave as if it had more memory than it really has, by using disk space to simulate RAM (random-access memory). In the 80386 and higher Intel CPU chips, and in most other modern microprocessors (such as the Motorola 68030, Sparc, and Power PC), exists a piece of hardware called the Memory Management Unit, or MMU.

The MMU treats memory as if it were composed of a series of “pages.” A page of memory is a block of contiguous bytes of a certain