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

Explain quick fit algorithams, QUICK FIT ALGORITHAMS Here we keep apart...

QUICK FIT ALGORITHAMS Here we keep apart lists for holes and processes. Therefore this reduces the searching time for holes Hole list and Process list. If we organize the li

What are the different thread levels?, What are the different thread levels...

What are the different thread levels? There are two broad type of thread implementation: User-Level Threads -- Thread Libraries. Kernel-level Threads -- System Calls.

Objective, what are the objective of operating system assignment

what are the objective of operating system assignment

Illustrate example for segmentation, EXAMPLE FOR SEGMENTATION Consider ...

EXAMPLE FOR SEGMENTATION Consider an instance as given in the table and we have five segments numbered from 0 through 4 the segment is stock in the physical memory as shown. Th

Explain the spawnvp function used in the netware, Explain the Spawnvp Funct...

Explain the Spawnvp Function used in the netware Spawnvp(flags, execNmae, argv)   This function executes  similarly to spawnlp( ) except that parameters are passed as a v

Contiguous-memory allocation, Compare contiguous-memory allocation with pur...

Compare contiguous-memory allocation with pure paging in the following aspects: 1. In support of dynamic memory allocation: most systems allow programs to allocate more memory t

Principles of operating systems, Objective - Tiny Shell (tish) In this...

Objective - Tiny Shell (tish) In this exercise you will write a small shell program to run different programs in foreground and background mode. Background Usually when

Describe swapping technique in unix systems, Describe swapping technique in...

Describe swapping technique in UNIX systems. Swapping is used to control memory contention among processes. If there is excessively much memory contention, processes are swappe

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