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

Define an assembly language, Define an assembly language  Assembly lan...

Define an assembly language  Assembly language stands for a Low level programming language

What happens when you high-level format a floppy disk, Question: a. The...

Question: a. The following questions refer to a generic Windows file system: i) Describe what happens when you high-level format a floppy disk? ii) What is the maximum size

Backup and recovery, what is it all about? why do we need? what are the typ...

what is it all about? why do we need? what are the types of backup? how is it done in unix?

Distinguish between long and short term scheduler, Question 1: a) Disti...

Question 1: a) Distinguish between "Long-Term Scheduler" and "Short-Term Scheduler". b) Describe the benefits of "Threads". c) Name three types of CPU Scheduling. Que

Describe the state when you run an unlink operation, Describe when you run ...

Describe when you run an unlink() operation to remove a file on the ext3 file system. Be specific about what disk blocks have to be written where in what order. State your assumpti

Explain the various methods of file access, Operating Systems 1. Illust...

Operating Systems 1. Illustrate the Microkernel Architecture with suitable diagram. 2. When Deadlock occurs? What are the Necessary Conditions for Deadlock? 3. Describe f

Describe what is meant by client-server computing, Question 1: (a) Desc...

Question 1: (a) Describe what is meant by Client-server Computing? (b) Distinguish between a server process and a client process. (c) What are the basic characteristics o

Android operating system, Android operating system is an open source, Linux...

Android operating system is an open source, Linux-based Smartphone OS. It is the world's most popular mobile platform with more than 700,000 applications and 25 billion downlo

What is the use of boot block, What is the use of boot block? For a com...

What is the use of boot block? For a computer to begin running when powered up or rebooted it requires having an initial program to run. This bootstrap program tends to be easy

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