Identifying parallelism, Operating System

Assignment Help:

Identifying parallelism

A formal way to identify parallelism in an activity is to draw a task dependence graph in a directed graph in which each vertex represents a task to be completed. An edge from vertex u to vertex means that task u must be completed before task v begins, so that task v "depends on" u. If there is no path from u to v, then the tasks are independent and may be performed concurrently. Consider the following problem: Alice is the leader of a crew of workers who maintain a large estate. There are four principal tasks: mowing the lawns, pruning the trees and hedges, repairing the fences, and inspecting the work to ensure it has all been done satisfactorily. Mowing must be completed before the work is inspected, as must the pruning and fence repair. The estate has a security system which must be switched off before work commences (i.e. before Alice and her team arrives), and switched on again after the team leaves.

  • Draw the dependence graph corresponding to the above problem, showing all the tasks involved. (In a project management plan, this scheme is often referred to as a "work breakdown structure").
  • Alice has 8 people in her crew, including herself. (The crew members are: Alice, Bert, Cressida, Dominic, Edgar, Frank, Gus and Harriet). Alice will be solely responsible for inspecting the work, but decides that she herself and three other people (Bert, Dominic and Gus) will mow the estate's four lawns (referred to as north, south, west and east lawns, each of which are of equal area), two other people (Cressida and Frank) will prune the trees, whilst Edgar and Harriet will repair the fences. Redraw the graph to show the allocation of the crew to particular tasks. (Hint: a single task in the original graph may be come multiple tasks in the revised version, each of which is performed by a particular person).
  • Alice is a fast worker, and can mow any of the lawns in one hour, as can Dominic. Frank and Gus can complete any of the manual tasks in two hours. Bert, Cressida, Edgar and Harriet take three hours to do their work. If the manual work starts at 10:00 a.m. in the morning, at what time scan Alice inspect the work? In your answer, refer to the dependence graph showing the allocation of crew to tasks.

Since mowing is done first and then all team members start the work simuntaneosly and Alice can only inspect after each has finished their task the time taken by the slowest team members will be seen here.

Harriert/Bert/Credessia and Edgar take 3 hrs each to complete their task.

The manual work starts at 10.00 AM so the inspection will start 3+3 =6 hrs after that.


Related Discussions:- Identifying parallelism

What is an effector process, What is an effector process? The effector ...

What is an effector process? The effector process is a method that verifies itself.The effector process exists in particular criteria.

Task decomposition and data decomposition, Discuss the concepts of  task de...

Discuss the concepts of  task decomposition  and  data decomposition  within the context of parallel programming. Parallel programming or parrelel computing is the simultaneo

Define a policy for data storage, Produce a referenced four page report whi...

Produce a referenced four page report which describes the possible functionality of the system; similar systems that are out there and different possible approaches to delivering t

Race condition, list the prevention of mechanism for race condition with op...

list the prevention of mechanism for race condition with operating system

Write a short note on peer-to-peer computing, Write a short note on peer-to...

Write a short note on peer-to-peer computing. Peer-to-peer (P2P) system model is a kind of distributed OS. In this model, clients and servers aren't distinguished from one anot

Keeping track of free memory, How do we keep track of where the free pieces...

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

Define ufd and mfd, Define UFD and MFD. In the two-level directory stru...

Define UFD and MFD. In the two-level directory structure, every user has her own user file directory (UFD). Every UFD has a similar structure, but lists only the files of a one

Define file permission in unix, The permission function is used to calculat...

The permission function is used to calculate what, if any access each class or level of user has to each file on a Unix machine. The permission task is one of the data components s

The key challenges of distributed systems, Question 1 Explain the followin...

Question 1 Explain the following with respect to Resource Management in Distributed Systems- Task assignment Approach Load - Balancing Approach Load - Sharing Approach

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd