Wednesday, January 14, 2009

Concept of Thrashing

If the number of frames allocated to a low priority process is lower than the minimum number required by the computer architecture then in this case we must suspend the execution of this low priority process.After this we should page out all of its remaining pages and freeing all of its allocated frames.This provision introduces a swap in,swap-out level of intermediate CPU scheduling.Let take a example of a process that does not have enough number of frames.If the process does not have the number of frames it needs to support pages in active use, it will quickly page fault.The oly option remains here for process is to replace some active pages with the page that requires a frame.However,since all of its pages are in active use,it must replace a page that will be needed again right away.Consequently,it quickly faults again and again that mean replacing pages that it must bring back in immediately.This high paging activity is called Thrashing.Or we can say that a process is Thrashing if it is spending more time in paging then executing.Thrashing results in severe performance problems.


Anonymous said...

Thnaks... this helps me and remove misconception about thrashing