Skip to main content

Explain Thrashing

Thrashing is said to occur when the system spends a large amount of time transferring shared data blocks from one node to another, compared to the time spent doing the useful work of executing application  processes. It is serious performance problem with DSM systems that allow data blocks to migrate from one node to another. Thrashing may occur in the following situations:

a.  When interleaved data accesses made by processes on two or more nodes causes a data block to move back and forth from one node to another in quick succession.

b.  When blocks with read-only permissions are invalidated soon after they are replicated. Following methods may be used to solve the thrashing problem in DSM systems:

a.  Providing  application-controlled  locks.  Locking  data  to  prevent  other  nodes  from accessing that data for a short period of time can reduce thrashing.

b.  Nailing a block to a node for a minimum amount of time. Another method to reduce thrashing is to disallow a block to be taken away from a node until a minimum amount of time t elapses after its allocation to that node. The time can either be fixed statically or be tuned dynamically on the basis of access patterns.

c.  Tailoring the coherence algorithm to the shared-data usage patterns. Thrashing can be minimized  by  using  different  coherence  protocols  for  shared  data  having  different characteristics.

Comments

Popular posts from this blog

Introduction to JavaScript- Basics

JavaScript is the most popular scripting language on the internet, and works in all major browsers, such as Internet Explorer, Firefox, Chrome, Opera, and Safari. What You Should Already Know Before you continue you should have a basic understanding of the following: HTML and CSS If you want to study these subjects first, find the tutorials on our Languages page . What is JavaScript? JavaScript was designed to add interactivity to HTML pages JavaScript is a scripting language A scripting language is a lightweight programming language JavaScript is usually embedded directly into HTML pages JavaScript is an interpreted language (means that scripts execute without preliminary compilation) Everyone can use JavaScript without purchasing a license Are Java and JavaScript the same? NO! Java and JavaScript are two completely different languages in both concept and design! Java (developed by Sun Microsystems) is a powerful and much more complex programming language ...

IBM Sample Problem Using Speed

Question 1 A policeman starts chasing a thief 30 minutes after the thief had run from a spot. With an average speed of 20km per hour, he takes 2 hours to catch the thief. What is the average speed of the thief? a)16km/hr b)25km/hr c)24km/hr d)18km/hr Answer : a)16km/hr Solution: As given, the average speed of the policeman = 20km/hr. He takes 2 hours to catch the thief, so from formula, "distance = speed x time" we have The total distance covered by the police to catch the thief = 20 x 2 = 40 km (This value is also equal to the distance run by thief before being caught by Police.) Policeman had started late by 30 minutes and took 2 hours to catch the running thief. Above means that the thief takes (30minutes + 2 hours =) 5/2 hours to reach 40km. So the speed of the thief = 40/(5/2) = 40 x 2 / 5 = 16 km/hr. Hence the answer is 16km/hr. Question 2 From a particular spot, Tom started to chase Jerry which had left the spot before 30 minutes. Tom ran acro...

MCA - Syllabus, Notes, Question Papers, Projects

MCA - Syllabus, Notes, Question Papers, Projects : SEMESTER - 1 Syllabus: Syllabus PDF Notes: Semester 1 Notes Question Papers:  Project: SEMESTER - 2 Syllabus: Syllabus PDF                                   Notes: Semester 2 Notes Question Papers:  Projects:  SEMESTER - 3  Syllabus: Syllabus PDF                                   Notes: Semester 3 Notes Question Papers:  Project: SEMESTER - 4  Syllabus: Syllabus PDF                               ...