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 the sleep (ms) function, Explain the Sleep (ms) Function  This ...

Explain the Sleep (ms) Function  This call places the current thread in a suspended state for the number of milliseconds passed as the parameter (ms). After that Windows NT wil

Assembly, Write a program that will input two numbers from the keyboard and...

Write a program that will input two numbers from the keyboard and execute each of the signed and unsigned multiply and divide instructions. For each instruction, the program shoul

Mark-sweep, The objects that a program can access directly are those object...

The objects that a program can access directly are those objects which are referenced by local vari-ables on the processor stack, or by any global/static variables that refer to ob

Ipc, Explain in detail about ipc in linux

Explain in detail about ipc in linux

Explain the circumstances under which os use mutexes, Q. Give the reasons ...

Q. Give the reasons why Windows XP, Solaris and Linux implement multiple locking mechanisms. Explain the circumstances under which they use mutexes, spinlocks, semaphores, adaptiv

Define criterion for classification of data structures, Define what can be ...

Define what can be used as a criterion for classification of data structures utilized in language processing              Answer: nature of a data structure, lifetime of a dat

Catalogue the design goals of windows xp, Q. Catalogue the design goals of ...

Q. Catalogue the design goals of Windows XP. Answer: Design goals comprise security and reliability and Windows and POSIX application compatibility with high performance and ex

Deadlock resoloution technique, justify the role played by the operating sy...

justify the role played by the operating system in managing the process to avoid deadlock

Explain single level directory structure, Single level directory: This ...

Single level directory: This is the easiest directory structure. All the files are controlled in the same directory, which is simple to support and understand. Few of the li

Define the dossleep(ms) function used in the os/2, Define the DosSleep(ms) ...

Define the DosSleep(ms) Function used in the os/2 DosSleep()  suspends the currently executing  thread for some time interval specified in the  ms parameter. If a value of 0 is

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