Free Bsd Memory Management

Free BSD Memory Management

An essential element of an operating system is the memory management system and these facilities are the managers of the resources on a system. Of these memory facilities main memory is the most central as it speaks directly to the CPU. After which comes secondary storage or backing storage that is usually on moving head disk drives and tend to be of a larger storage volume that main memory. With the advent of multi-programmed environments the need to share memory resources with all the processes that require them became vital and commonplace. This allowed for the allocation and de-allocation of memory resources for all the processes that need it.

The Free bsd Memory Management is built on a configuration platform where each process is given its own private virtual address space. The given address space is then divided into three logical segments; text, data and stack. This entire address space is housed in main memory and the system pages the necessary information into memory. By doing this if there is a shortage of system resources, then there is a two-level approach to maintain resources. If the resources are low then the system will seek out processes that have resources that were not used in a while and free those up to make them available to the system for needed resources. Also, if the shortage is very bad then the system will move resources to secondary storage. This two level approach is known as demand paging and swapping and does not affect the operation of processes in the system.

In allocating a virtual address space a range of memory locations are referenced by a process independently of the physical memory that is in the system. These virtual address spaces are translated into references by hardware to physical memory by on operation know as address translation. This operation allows programs to be loaded into memory without mandating that the position dependent addresses be changed in the program. The benefits of...