Logical Structure of a directory Logical Structure of a directory: The directories can be structured in the following ways: Single level directory Two level directory Tree structure directory Acyclic graph directory General graph directory 1. Single Level directory It is the simplest form of Logical Structure of a directory having only one level of directories.… Read More »
A Directory is a symbol table of files that stores all the related information about the file it holds with the contents. Thus, a directory is a list of files. Each entry of a directory defines a file. A typical directory entry may contain the information like file name, type, its version number, size, owner… Read More »
Access Methods in File Management Files are used to store data. The information present in the file can be accessed by various methods. Thus, the way of retrieving data from a file is known as access method. Different systems use different access methods. The various access methods used are: Sequential access Direct access Indexed access… Read More »
File Concept A file is a logical collection of information stored on secondary storage such as hard disk. Physically, a file is the smallest allotment of secondary storage device e.g., disk. Logically, a file is a sequence of logical records i.e. a sequence of bits and bytes. Files can be used to contain data and… Read More »
Thrashing Thrashing is a situation in which a system spends more time in processing page faults than executing instructions of processes. Thrashing degrades the performance of a system. There may be a situation when the memory is full with pages that are accessed frequently. A page fault will occur if the required page is not… Read More »
Difference between Global and Local Page Replacement Global page replacement In global replacement a process can select even that frames which is currently allocated to some other process. Thus, in this strategy, one process can take a frame from another process. In global replacement, the number of frames allocated to a process may increase. One… Read More »
Allocation Algorithm There are two different methods of allocating frames to different process. These are: Equal allocation Proportional allocation 1. Equal allocation This allocation method divides the available page frames equally among all the processes. i.e. if we have m frames and n processes then we can divide m frames among the n processes. For… Read More »
Locality Central to most memory management techniques is the concept of locality – that processes tend to reference storage in nonuniform, highly localized patterns. Locality exhibit itself in two forms: Temporal locality Spatial locality 1. Temporal Locality Temporal locality means that storage locations referenced recently are likely to be referenced in the near future. For… Read More »
Page Replacement Algorithms When a page fault occurs, the operating system has to choose a page to remove from memory to make space for the page that has to be brought in. If the page to be removed has been modified in memory, it must be rewritten to the disk to bring the disk copy… Read More »
Segmentation is a memory management technique in which process is dividing into the segments and the segments are of variable size. The details about each segment are stored in a table called a segment table. Segment table is stores mainly two information of the segments. Base: It is the base address of the segment Limit:… Read More »