In a pure segmentation architecture, segments are allocated like variable partitions, although the memory management hardware is involved in decoding addresses. Pure segmentation addresses replace the page identifier in the virtual address with a segment identifier, and find the proper segment (not page) to which to apply the offset.
Thrashing
its depends on number of processes in memory.
thrashing
Paging is a memory management scheme that permits the physical- address space of process to be noncontiguous.
paging is the process of memory management in which memory is allocated in the non contiguous form,i.e. the program is break into block of fixed size known as page and also the main memory also break down into block of same size known as frame or page frame. Now all this page are brought into the main memory but in the space available so they can be contiguous if they find whole space required by the program or if the space is available but in scattered form then they can give space in non contiguous form. But in demand paging only those pages are brought into main memory which are required to execute the program at that time when a program need other pages it will swap out the unused pages from the main memory and swap in the desired page thus allowing it to execute the program though the space available is not sufficient to bring the whole program into main memory..................One of the problem arises due to demand paging is page fault which is caused due to required page not found in main memory for which we require swapping. hey if you like my post don't forget to thank me....... for any further queries e-mail me at hemant_spidey3@yahoo.co.in or 1989hemantrajput@gmail.com
The Intel Pentium supports pure segmentation and segmentation with paging. The processor creates logical addresses, which are mapped to physical addresses by the segmentation unit. Those addresses may point to physical addresses within memory or paged swap space.
In demand paging, a page is not loaded into main memory until it is needed. In pure demand paging, even a single page is not loaded into memory initially. Hence pure demand paging causes a page fault. Page fault, the situation in which the page is not available whenever a processor needs to execute it.
Contiguous memory allocation scheme suffers from external fragmentation as address spaces are allocated contiguously and holes develop as old processes die and new processes are initiated. It also does not allow processes to share code, since a process's virtual memory segment is not broken into non-contiguous fine-grained segments. Pure segmentation also suffers from external fragmentation as a segment of a process is laid out contiguously in physical memory and fragmentation would occur as segments of dead processes are replaced by segments of new processes. Segmentation, however, enables processes to share code; for instance, two different processes could share a code segment but have distinct date segments. Pure paging does not suffer from external fragmentation, but instead suffers from internal fragmentations. Processes are allocated in page granularity and if a page is not completely utilized, it results in internal fragmentation and a corresponding wastage of space. Paging also enables processes to share code at the granularity of pages.
fail....
Paging is a technique with the help of which we can divide the memory into pages which help us to easly access the files and it also decreases the Execution time (Saves SYSTEM time). It also creates a mirage of Memory.
Paging requires more memory overhead to maintain the translation structures. Segmentation requires just two registers per segment: one to maintain the base of the segment and the other to maintain the extent of the segment. Paging on the other hand requires one entry per page, and this entry provides the physical address in which the page is located.
Paging refers to the division of address spaces into fixed size units and the logical addresses are in the form of tuples. On the other hand, segmentation is the dividing of address spaces into a defined number of segments.
Advantages of segmentation over paging: Speed. Reloading segment registers to change address spaces is much faster than switching page tables. Segment descriptor tables consume less memory than page tables. x86 page table entries do not have an 'Executable' bit. With segmentation, you can make a region of memory executable (code) or not (data). Segment size can be byte-granular (size 1 byte to 1Meg in units of 1 byte); pages are always page-granular (size 4K to 4Gig in units of 4K). Segmentation lets you make the segment as large as necessary, with no excess (there is no internal fragmentation).
The definition of Mass segmentation is very similar to Marketing segmentation. While there is an abundance of markets, it is necessary to divide them into regions, geographical, and cultural sections. This is so better to accommodate according to their local communication needs.
It is paging.
Paging You ended in 1946.
Difference between paging and what?