Channels ▼
RSS

Parallel

Fundamental Concepts of Parallel Programming


Shameem Akhter, a platform architect at Intel, and Jason Roberts, a senior software engineer at Intel, are the authors of Multi-Core Programming: Increasing Performance through Software Multithreading on which this article is based. Copyright (c) 2008 Intel Corporation. All rights reserved.


Developers who are unacquainted with parallel programming generally feel comfortable with traditional programming models, such as object-oriented programming. In this case, a program begins at a defined point, such as the main() function, and works through a series of tasks in succession. If the program relies on user interaction, the main processing instrument is a loop in which user events are handled. From each allowed event -- a button click, for example -- the program performs an established sequence of actions that ultimately ends with a wait for the next user action.

When designing such programs, developers enjoy a relatively simple programming world because only one thing is happening at any given moment. If program tasks must be scheduled in a specific way, it's because the developer imposes a certain order on the activities. At any point in the process, one step generally flows into the next, leading up to a predictable conclusion, based on predetermined parameters.

To move from this linear model to a parallel programming model, designers must rethink the idea of process flow. Rather than being constrained by a sequential execution sequence, programmers should identify those activities that can be executed in parallel. To do so, they must see their programs as a set of tasks with dependencies between them. Breaking programs down into these individual tasks and identifying dependencies is known as decomposition. A problem may be decomposed in several ways: by task, by data, or by data flow. Table 1 summarizes these forms of decomposition. As you shall see, these different forms of decomposition mirror different types of programming activities.

Table 1: Major Forms of Decomposition


Related Reading


More Insights






Currently we allow the following HTML tags in comments:

Single tags

These tags can be used alone and don't need an ending tag.

<br> Defines a single line break

<hr> Defines a horizontal line

Matching tags

These require an ending tag - e.g. <i>italic text</i>

<a> Defines an anchor

<b> Defines bold text

<big> Defines big text

<blockquote> Defines a long quotation

<caption> Defines a table caption

<cite> Defines a citation

<code> Defines computer code text

<em> Defines emphasized text

<fieldset> Defines a border around elements in a form

<h1> This is heading 1

<h2> This is heading 2

<h3> This is heading 3

<h4> This is heading 4

<h5> This is heading 5

<h6> This is heading 6

<i> Defines italic text

<p> Defines a paragraph

<pre> Defines preformatted text

<q> Defines a short quotation

<samp> Defines sample computer code text

<small> Defines small text

<span> Defines a section in a document

<s> Defines strikethrough text

<strike> Defines strikethrough text

<strong> Defines strong text

<sub> Defines subscripted text

<sup> Defines superscripted text

<u> Defines underlined text

Dr. Dobb's encourages readers to engage in spirited, healthy debate, including taking us to task. However, Dr. Dobb's moderates all comments posted to our site, and reserves the right to modify or remove any content that it determines to be derogatory, offensive, inflammatory, vulgar, irrelevant/off-topic, racist or obvious marketing or spam. Dr. Dobb's further reserves the right to disable the profile of any commenter participating in said activities.

 
Disqus Tips To upload an avatar photo, first complete your Disqus profile. | View the list of supported HTML tags you can use to style comments. | Please read our commenting policy.
 

Video