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what are the drawbacks of contiguous allocation of disk spacethe disadvantages area suffers from internal fragmentationb suffers from external
what are the advantages of contiguous allocationthe advantages area supports direct accessb supports sequential accessc number of disk seeks is
what are the allocation methods of a disk spacemethods of allocating disk space which are widely in use area contiguous allocationb linked
define seek time and latency timethe time taken by the head to move to the appropriate cylinder or track is known as seek time once the head is at
what are the functions of virtual file system vfsa it separates file-system-generic operations from their execution defining a clean vfs interface it
what are the various layers of a file systemthe file system is composed of many dissimilar levels each level in the design uses the feature of the
what is beladys anomaly when plotting on a graph the page faults versus the number of available frames we notice that the number of faults for four
explain fifo page replacementa fifo replacement algorithm associates with every page the time when that page was brought into memory when a page must
what is reference stringwe evaluate an algorithm by running it on a definite string of memory reference and computing the number of page faults the
briefly discuss on page replacement page replacement approach is fixed as follows if no frame is free we search one that is not presently being used
enhanced second-chance algorithmwhen we increase the second-chance algorithm by considering both the reference bit and the modify bit as an order
second-chance algorithmwhen a page has been selected we inspect its reference bit if the value is 0 we proceed to replace this page if the reference
additional-reference-bits algorithmwe can keep an 8-bit byte for every page in a table in memory the operating system shifts the reference bits right
internal file structureall disk io is performed in units of single block and all blocks are the similar size it is unlikely that the physical record
file structurecertain files must conform to a needed structure that is understood by the operating system the operating system may consist that an
explain the various file typesa common technique for executing file types is to contain the type as part of the file name the name is split into two
we are faced with three major components of the page-fault service time 1 service the page-fault interrupts2 read in the page3 restart the
a page fault causes the following sequence to occur1 trap shut in to the operating system2 save the process registers and process state3 verify that
performance of demand pagingdemand paging can have an important effect on the performance of a computer system as long as there are no page faults
the hardware to support demand paging is as follows page table this table has the skill to mark an entry invalid though a valid-invalid bit or
the procedure for handling the page fault is as follows1 we check the internal table to verify whether the reference was valid or invalid2 if the
basic conceptswhen a process is to be changed in the pager guesses which pages will be used before the process is changed out again instead of
explain about demand paginga demand paging system is same to a paging system with swapping processes reside on secondary memory when we require
what are files and explain the access methods for filesfile definitionattributes operations and typesdirect accesssequential access with diagramother
explain the various page replacement strategiespage replacement-basic scheme with diagramoptimal page replacementlru page replacementfifo page