Double duty for video cards

How graphics processing units are being used for hard-core number crunching.

When the next version of the Mac operating system, code named Snow Leopard, is released later this year, users might experience some surprising boosts in speeds, at least for some applications. The time it takes, for instance, to re-encode a high-definition video for an iPod could dramatically decrease from hours to a few minutes.

The secret sauce for this boost? Snow Leopard will have the ability to hand off some of the number crunching in that conversion to the graphics processing unit (GPU). The new OS is scheduled to include support for Open Computing Language, which allows programmers to have their programs tap into the GPU.


Related stories:

How to write apps for multiple cores: Divide and conquer
Does parallel processing require new languages?
Double-duty for video cards 


Typically, the GPU, usually embedded in a graphics card, renders the screen display for computers. But ambitious programmers are finding that GPUs can also be used to speed certain types of applications, particularly those involving floating-point calculations.

For instance, researchers at Belgium’s University of Antwerp outfitted a commodity server with four dual-GPU Nvidia GeForce 9800 GX2 graphics cards. The server would be used to look for ways to improve tomography techniques. They found that this configuration could reconstruct a large tomography image in 59.9 seconds, which is faster than the 67.4 seconds it took an entire server cluster of 256 dual-core Opterons from Advanced Micro Devices.

The cluster cost the university $10 million to procure, whereas the researchers' server only ran $10,000.

For a certain group of problems, GPUs can provide a lot more computational power than an equivalent number of central processing units (CPUs), argued Sumit Gupta, senior product manager for Nvidia’s Tesla line of GPU-based accelerator cards.

In order to render material visual displays, GPUs have been tweaked to do lots of floating-point computations. This sort of computation differs from the integer-based operations that CPUs usually perform insofar that integer computation truncates calculations on the right side of the decimal point, which could lead to small rounding errors. Floating-point operations carry out rounding to 32 bits (and double floating point carries it out for 64 bits). The hard-number crunching of scientific research, in particular, requires the accuracy of floating-point operations.

Graphics cards have always excelled at this kind of floating-point computation, Gupta said. In order to portray tree leaves fluttering in the wind or water trickling over a streambed of the latest computer game, the GPU has to calculate the color, depth and other factors of each screen pixel, which requires heavy matrix multiplication to floating-point precision. These sorts of calculations are not unlike those scientists need to do to solve mathematical conundrums in molecular dynamics, computational chemistry, signals processing and the like.

Nvidia, for one, has seen the interest in having the GPU do double-duty and has modified some of its cards to make them fully programmable. The Nvidia Tesla C1060 computing board is being offered for the scientific crowd. It has one GPU with more than 240 processor cores. It can offer 933 million floating-point operations per second.

To help programmers tap into this computational power, Nvidia has created a package of tools named Cuda. Part of this package is a library for the C programming language, called C Cuda. It offers a number of parallel keywords that developers can use to break off portions of their code to run on the GPU. They just insert the name of the library in their C code, and then they are able to use the functions to signify chunks of the code that can be run in parallel.

Cuda has proven popular with developers. More than 75 research papers have been written on Cuda, and more than 50 universities teach how to use the platform, Gupta said. Certainly, the Cuda sessions were among the best-attended at the SC08 conference in Austin, Texas, last fall.

Even with tools such as Cuda, however, writing for GPUs certainly makes the job of programming a little bit more complicated. For its own developers, government integrator Lockheed Martin, via its Advanced Technology Laboratories, is looking at ways to ease programming in heterogeneous processor environments.

"If you use a GPU, you need to learn the Nvidia compiler and learn how to put the appropriate extensions into your code in the GPU," noted Daniel Waddington, principal research scientist at Lockheed Martin’s labs. He is leading an effort to build what he calls a refactoring engine. Called Chimera, this software will be able to recompile code written in well-known languages so it can be reused across a wider variety of processors without the programmer needing to know the low-level implementation details of the GPUs or other new types of processors.

"The problem is not only are designers moving to multicore processors, but designers are coming out with new designs a few times a year," said Lockheed Martin research scientist Shahrukh Tarapore, who also is working on Chimera. “They have different programming models and different capabilities.”

Right now, Chimera works with the C and C++ languages, which are widely used within Lockheed Martin. If successful, Chimera could be used by the company’s programmers to quickly build programs that can take advantage of the latest processors — be they CPUs, GPUs or even some other design.

"Your source code is first transformed into an abstract syntax tree [so] it can be translated into other forms," explained Tarapore. This approach will also identify which sections can be broken into chunks that could be run in parallel. Those pieces are then pulled from the main body of the program and replaced with pointers to components that can execute the tasks on specific pieces of hardware

X
This website uses cookies to enhance user experience and to analyze performance and traffic on our website. We also share information about your use of our site with our social media, advertising and analytics partners. Learn More / Do Not Sell My Personal Information
Accept Cookies
X
Cookie Preferences Cookie List

Do Not Sell My Personal Information

When you visit our website, we store cookies on your browser to collect information. The information collected might relate to you, your preferences or your device, and is mostly used to make the site work as you expect it to and to provide a more personalized web experience. However, you can choose not to allow certain types of cookies, which may impact your experience of the site and the services we are able to offer. Click on the different category headings to find out more and change our default settings according to your preference. You cannot opt-out of our First Party Strictly Necessary Cookies as they are deployed in order to ensure the proper functioning of our website (such as prompting the cookie banner and remembering your settings, to log into your account, to redirect you when you log out, etc.). For more information about the First and Third Party Cookies used please follow this link.

Allow All Cookies

Manage Consent Preferences

Strictly Necessary Cookies - Always Active

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data, Targeting & Social Media Cookies

Under the California Consumer Privacy Act, you have the right to opt-out of the sale of your personal information to third parties. These cookies collect information for analytics and to personalize your experience with targeted ads. You may exercise your right to opt out of the sale of personal information by using this toggle switch. If you opt out we will not be able to offer you personalised ads and will not hand over your personal information to any third parties. Additionally, you may contact our legal department for further clarification about your rights as a California consumer by using this Exercise My Rights link

If you have enabled privacy controls on your browser (such as a plugin), we have to take that as a valid request to opt-out. Therefore we would not be able to track your activity through the web. This may affect our ability to personalize ads according to your preferences.

Targeting cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising.

Social media cookies are set by a range of social media services that we have added to the site to enable you to share our content with your friends and networks. They are capable of tracking your browser across other sites and building up a profile of your interests. This may impact the content and messages you see on other websites you visit. If you do not allow these cookies you may not be able to use or see these sharing tools.

If you want to opt out of all of our lead reports and lists, please submit a privacy request at our Do Not Sell page.

Save Settings
Cookie Preferences Cookie List

Cookie List

A cookie is a small piece of data (text file) that a website – when visited by a user – asks your browser to store on your device in order to remember information about you, such as your language preference or login information. Those cookies are set by us and called first-party cookies. We also use third-party cookies – which are cookies from a domain different than the domain of the website you are visiting – for our advertising and marketing efforts. More specifically, we use cookies and other tracking technologies for the following purposes:

Strictly Necessary Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Functional Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Performance Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Social Media Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Targeting Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.