05-10-2012, 03:15 PM
Priority Based Pre-emptive Task Scheduling for Android Operating System
Priority Based Pre-emptive.pdf (Size: 487.7 KB / Downloads: 77)
Abstract
Android mobile operating system which is based
on Linux Kernel 2.6, has open source license and adaptability
to user driven applications. As all other operating systems it
has all the basic features like process scheduling, memory
management, process management etc associated with it. Any
mobile platform works smoothly when the process scheduling
is performed in a proper way. Ideal platform is that in which
no resource conflict occurs. Thus scheduling in every manner
is essential for the operating system to adapt itself with the
requirement of a particular application. In this paper, priority
based pre-emptive task scheduling is proposed for the SMS
application. The idea is to define High priority to required
contacts, for ex. Contact numbers of parents or teachers will
be given High priority. If in case, any SMS from these High
priority contacts is received, the application would flash the
SMS on the active screen and redirect this High priority SMS
to the Priority Inbox.
INTRODUCTION
PERATING System is considered as efficient when
its throughput rate is high. Task scheduling, memory
management are the few aspects which makes it possible to
increase the response time of operating systems. Mobile
operating systems are the embedded devices which are
designed for the specific use and are expected to meet the
specific time deadlines for completing the tasks. For this,
the response time of the important tasks is most important
which can be achieved using the priority based task
scheduling. This paper puts forth the idea of applying the
pre-emptive based task scheduling for SMS application.
SMS is the technology that enables the sending and
receiving of messages over the network via exchange of
text files.
PRE- EMPTIVE TASK SCHEDULING
The key concept present in any operating system which
allows the system to support multitasking, multiprocessing,
etc. is Task Scheduling [1]. Task Scheduling is the core
which refers to the way the different processes are allowed
to share the common CPU. Scheduler and dispatcher are
the softwares which help to carry out this assignment [2].
Android operating system uses O (1) scheduling algorithm
as it is based on Linux Kernel 2.6. Therefore the scheduler
is names as Completely Fair Scheduler as the processes can
schedule within a constant amount of time, regardless of
how many processes are running on the operating system
[6], [7].
Pre-emptive task scheduling involves interrupting the
low priority tasks when high priority tasks are present in
the queue. This scheduling is particularly used for mobile
operating system as the CPU utilization is medium,
turnaround time and response time is high. Mobile phones
are required to meet specific time deadlines for the tasks to
occur.
EXPERIMENTAL RESULTS
From the available list of contacts in mobile phones, few
contacts which are important can be set as High priority
contacts. Android’s Emulator has been used for the
experimental purpose. Emulator is a virtual mobile device
that runs on the computer. The emulator allows developing
and testing Android applications without using a physical
device. In the following figures, the numbers like 5554,
5556 etc. resemble the 10 digit contact numbers present in
the mobile phone’s contact list.
ADVANTAGES OVER EXISTING SYSTEM
Various scheduling techniques are available for the
operating systems. O (1) scheduling algorithm is used for
the Linux Kernel [6], [7].
But Pre-emptive task scheduling is not available for SMS
application in any mobile operating system. This technique
is innovative and useful. It generally happens that
important SMS at times get merged in the inbox and it
takes lot of time to search the important SMS containing
the important data. Thus designing the high priority inbox
to segregate such important SMS solves the purpose.
The proposed technique works as an add-on for Android
Mobile Operating System. This technique facilitates to
categorize the contacts present in the mobile phone’s
contact lists as High or Default. Thus using this technique
helps in reducing the search time for important SMS files
received from the High priority contacts. Categorization of
important SMS is achieved by redirecting them to the
Priority Inbox. Thus this technique is useful where the
amount of SMS files to be dealt with is plenty.
OBSERVATIONS AND CONCLUSION
Proposed application aims towards better utilization of
the contacts list present in the mobile phones. It is rarely
thought of categorizing the important contacts as ‘High’
priority contacts and keeping other contacts are ‘Default’.
This idea has been thought of and has been implemented in
this application. A very basic and day to day used SMS
application has been targeted. This is done because SMS is
most widely used after the call application.
The proposed technique is used for the SMS files for the
Android Mobile Operating System. This feature of High
Priority Contacts and the pre-emptive task scheduling can
be extended for the Call application present on mobile
phones. Also mobile platforms like Symbian, Bada,
Windows, etc can be tested.