Differences in Memory Management Between Linux and Windows

Differences in Memory Management between Windows and Linux.
Antony Biagianti
3 June 2013
POS/355
Terance Carlson Differences in memory management between Windows and Linux. The topic of Memory Management (MM) between Windows and Linux is choice for explanation. The basic function of MM is to manage Random Access Memory (RAM) and hard disk memory available on the machine. Research shows that systems which manage memory of Windows and Linux have much in common. Data structures are one of the similarities. Another is memory mapped files to use with simple memory read or write instructions. Khetan lists other similarities as Hardware Abstaction Layer, Copy-on-write, Shadow paging, Background daemon, and Inter-Process Communication.
Page Replacement Page replacement is the area where they differ. Pages are swapped out from memory whenever free memory is needed. Windows creates a large pagefiles, and there can be one file in each disk partition. Windows has pagefiles stored on its partitions and nowhere else. Linux however calls this “swap space”, and it has two forms of it. Linux stores these files not only on a partition but also in what Sims describes as, “a special file in the filesystem that resides amongst your system and data files” (Sims, 2007, para. 10). So Linux has what they describe as a “swap partition,” and a “swap file.” The swap partition can be set up but the swap file gives the advantage of not needing to repartition a disk to add swap space.
Paging
Linux uses a three-level page table structure. This has a directory, middle directory, and a page table. Page allocation employs a buddy system by allowing the kernel to maintain a list of page frame groups that can be split and merged using a specific algorithm. Windows on the other hand, makes use of fixed-sized pages. Regions are set in these pages that have one of three states. The