Keeping track of free memory, Operating System

How do we keep track of where the free pieces of memory are? One idea is to maintain a set of linked-lists of free space; each linked-list will store free chunks of some given size (say, one list for chunks of 4 bytes, one for chunks of 8, 16, etc). This approach resembles the best-?t algorithm, since we can easily ?nd the list with chunks of memory that are the closest to what we need; the difference, of course, is that usually the linked lists store not objects of arbitrary size, but only powers of two. Also, we can never coalesce adjacent elements of the lists, or split elements, since then the very idea of segregating by size classes wouldn't make sense anymore. Another possible technique to keep track of free memory is called Big Bag of Pages (BiBOP). In this technique, a bunch of pages, usually segregated by size classes, is maintained such that there is a header on each page; on this header, among other things, we can ?nd a pointer to the next page of objects of that given size, and also a pointer to the ?rst free "slot" inside that page. Using the right optimizations we can make BiBOP ?nd and manage free slots of memory in O(1).

Posted Date: 3/12/2013 6:06:16 AM | Location : United States







Related Discussions:- Keeping track of free memory, Assignment Help, Ask Question on Keeping track of free memory, Get Answer, Expert's Help, Keeping track of free memory Discussions

Write discussion on Keeping track of free memory
Your posts are moderated
Related Questions
An operating system act as an intermediary between user of a computer and computer hardware. The objective of an operating system is to provide an environment in that a user can ex

Q. What are the tradeoffs concerned in rereading code pages from the file system versus using swap space to store them? Answer: If codes pages are accumulate in swap space th

Questiion 1 What is RTOS? What are its requirements? Questiion 2 Explain the structural elements of a real time system mode Questiion 3 What is kernel? Explain abo

FIXED PARTITIONING In a fixed partitioning, the operating system inhabiting some fixed portion of main memory is available for use of multiple processes -Using fixed partit

Explain with an example the need of Shift Alteration in critical section problem? Consider processes P i and P j and consider the algorithm for P i and P j .

How do we overcome the disadvantages of the two-level directory? Give links from one user directory to another, creating path names; system files become available by letting th

Explain the difference between internal and external fragmentation. Internal Fragmentation is the area in a region or a page that is not used by the job occupying that region o

we need an information about the different graph directory systems in detail by using shell sort . we also application part of directory systems in practical life. please help us i

People arrive at a barber shop at the rate of one every 4.5 minutes. If the shop is full (it can hold five people altogether), 30% of the potential customers leave and come back i

Interrupts The hardware mechanism that enables a device to inform the CPU is called an interrupt. The basic interrupt mechanism works as follows. The CPU hardware has a wire kn