Drawbacks of least-recently used algorithm, Operating System

The question of fairness, regarding page eviction, is a hard one. How do we decide what is fair? Many operating systems use global LRU, where pages from all processes are managed together using the approximate LRU algorithms described above. This is easy to implement, but has a number of problems.

For instance, with global LRU, there's no isolation between processes, and greedy or badly-written programs will push other programs out of physical memory. In addition, the priority which one gives a program is generally priority for the scheduler, not priority for physical memory (though there are approaches to try to deal with this).

There's also the "sleepyhead" problem, which is where an important but rarely-used programwill get paged out, and then start up slowly. For instance, the ntpd (network time protocol) program doesn't run often, but when it does run, it needs to make precise timing measurements, which would be impacted by pagefaults. ntpd and similar programs can get around this problem by "pinning" their pages, meaning that their physical pages are not allowed to be paged out to disk.

In general, the problem of fairness is that processes that are greedy (or wasteful) are rewarded; processes with poor locality end up squeezing out those with good locality, because they "steal" memory. There is no simple solution to this problem.

Posted Date: 3/12/2013 6:02:44 AM | Location : United States







Related Discussions:- Drawbacks of least-recently used algorithm, Assignment Help, Ask Question on Drawbacks of least-recently used algorithm, Get Answer, Expert's Help, Drawbacks of least-recently used algorithm Discussions

Write discussion on Drawbacks of least-recently used algorithm
Your posts are moderated
Related Questions
ADVANTAGES AND INCONVENIENCES OF KLT Advantages: the kernel be able to simultaneously schedule many threads of the same process on many processors blocking

DIFFERENT MULTITHREADING MODELS Multithreading Models the majority multithreading models fall into one of the following categories of threading implementation: 1.      M

fork and join syntax in java

WHAT IS OPERATING SYSTEM ?ENLIST AND EXPLAIN BASIC SERVICES PROVIDE BY OS

Question: (a) Answer the following questions based on the code snippet below. 1. int main (int argc, char *argv[]) 2. { 3. 4. pid_t processId; 5. 6. processId =

expalin about the design issues of network operating system

Question: (a) Define the term system software and application software, giving an example for each. (b) Draw a diagram to represent the abstract view of a computer system i

What are scheduling queues? Since the processes enter the system they are put into job queue. This queue contains all processes in the system. The processes that are exist in m

What are the various disk-scheduling algorithms? The several disk-scheduling algorithms are a. First Come First Served Scheduling b. Shortest Seek Time First Scheduling

What is page fault? In the computer storage technology a page fault is an exception which is raised by the memory management unit when a requested page isn't mapped in physical