Another semester down, two more to go

12 May, 2010 § 1 Comment

I’ve finished my third semester at Michigan State for my Masters in Computer Science. This past semester I took a special course on Natural Language Processing that looked at Language and Interaction and a separate course on Advanced Computer Architecture.

I plan on taking Design & Theory of Agorithms and Artificial Intelligence in the Fall, and Advanced Operating Systems and Translation of Programming Languages (aka Compilers) in the Spring.

I’m on track to finish my degree by May, 2011.

The Thirteen Dwarfs

12 May, 2010 § Leave a comment

This article was written by Brendan Grebur and Jared Wein.

Introduction

Adapting to the next step in processor technology requires a reevaluation of current computational techniques. Many-core architecture presents a fundamentally different perspective on both software and hardware systems. With no clearly effective model to follow, we are left to our own devices for advancement. A dwarf’s approach provides guidance, but does not guarantee an effective realization of the underlying issues. However, it provides a starting point to explore the interactions of data at extreme levels of parallelism. Of course, as with any method, pitfalls may arise.

This paper is a critique of the research presented by [Asanovic 06]. We present the motivation for their work, a comparison between their proposal and present-day solutions, as well as a look at advantages and disadvantages of their proposal.

Motivation

The past 16 years, from 1986 to 2002, have showed tremendous growth in processor performance. Around 2002, the industry hit a “brick wall” when it ran in to limits in memory, power, and instruction level parallelism [Hennessy and Paterson 07]. While performance gains slowed, performance requirements continued to grow at a higher pace than before.

As an example, Intel has been forecasting an “Era of Tera”. Intel claims that the future holds a time where there is demand for teraflops of computing power, terabits per second of communication bandwidth, and terabytes of data storage [Dubey 05]. To prepare for this era, Intel has claimed a “sea change” in computing and put their resources on multi- and many-core processor architectures [Fried 04].

Previously these multi- and many-core computer architectures have not been successful stays in the mainstream [Asanovic 06]. Some reason that one of the causes for poor adoption is the increased complexity when working with parallel computing. [Asanovic 06] developed thirteen independent paradigms that represent the active areas of parallel computing. After compiling their list, they compared theirs with Intel’s list and noticed heavy overlaps between the two. This reassured [Asanovic 06] that they were on the right path.

Advantages of the Dwarfs

The first advantage to the dwarfs that have been proposed is that there exists only a relatively small number of dwarfs to be concerned with. Psychology research has shown that humans can cope with understanding about seven, plus or minus two, items very easily [Miller 56]. The number of dwarfs, at 13, is not too far off from this desirable number, and allows the test space to be conceivably small. Had the number of dwarfs proposed been in the hundreds, it may become too costly to determine if a system can handle all the dwarfs.

Another advantage focuses on benchmarking software. Some of the programs for SPEC benchmarks work on computational problems that are no longer current research areas and have less of an application when determining the system performance. The dwarf approach has a goal to focus on active areas within computer science, and to adapt the focus areas over time to stay relevant.

The years since assembly programming have shown that higher level languages could be created and provide software developers with increased productivity while maintaining software quality. The goal of the parallel programming dwarfs is to extend these common problems to programming frameworks that can help software developers program at an even higher level to maintain efficiency and quality. These dwarfs provide themselves in a way that they can be looked at in the same regard as object-oriented design patterns. One such study was able to use the dwarfs to easily find places within existing sequentially-programmed applications where refactoring could make use of parallel programming solutions [Pankratius 07]. The researchers in this study were able to achieve performance improvements of up to 8x using autotuning and parallel programming patterns described by the dwarfs.

Disadvantages of the Dwarfs

There are a number of questions that haven’t been answered by the Berkeley researchers. We present a couple of the issues below that we are either unsure of or believe are disadvantages of the dwarf paradigm.

First, it is not well-explained how the combination of dwarfs is supported on a given system. When a system claims to support two dwarfs independently, there does not appear to be a deterministic answer as to if the system will support the combination of the dwarfs. Further, the interaction between these dwarfs does not appear to be well documented.

Next, [Asanovic 06] states the power of autotuning when working with sequential programming, but admits that there have not been successful implementations of an autotuner for parallel programs. The problem space for parallel programs is much larger than that of sequential programs, and various factors will have to be elided to make development of an autotuner reasonable. Further, it is unclear if the parameters used to perform the autotuning will provide the optional parameters for use when running the actual software with vastly different datasets than that of the autotuned dataset.

Last, the area of parallel programs presents a virtual graveyard of companies and ideas that have failed to reach the market successfully. The multi- and many-core architectures have failed at producing the same programmer productivity and quality that the uniprocessor delivered. Only time will tell how the field of software development reacts and if it can adopt the shift in computing paradigms.

Conclusion

Computing performance improvements have recently hit a “brick wall” and there has been a computing shift pushed by major chip makers towards multicore systems. There are many complexities with multi- and many-core systems that can lead to unappreciated performance gains. Some of the problems may reside in the complexity of implementing common parallel computing patterns.

The researchers in the Par Lab at University of California at Berkeley have been attacking the multi- and many-core problems since 2006. From their research, they have created a list of 13 dwarfs that represent active areas in parallel computing. These dwarfs provide common patterns that can be reproduced and used for benchmarking and the creation of programming frameworks that offer an abstraction of complex problems.

Citations

Asanovic et al. The Landscape of Parallel Computing Research: A View from Berkeley. Dec 2006.

Fried, I. For Intel, the future has two cores. ZDNet. 2004. http://news.zdnet.com/2100-9584_22-138241.html

Dubey, P. Recognition, Mining and Synthesis Moves Computers to the Era of Tera. Technology@Intel Magazine. Feb 2005.

Hennessy, J. and Patterson, D. Computer Architecture: A Quantitative Approach, 4th edition, Morgan Kauffman, San Francisco, 2007.

Miller, G. A. “The magical number seven, plus or minus two: Some limits on our capacity for processing information”. Psychological Review. Vol 63, Iss 2, pp 81–97. 1956.

Pankratius et al. Software Engineering for Multicore Systems – An Experience Report. Institute for Program Structures and Data Organization. Dec 2007.

Moving Objects Through A Terrain Using Tiled Velocity Fields

16 December, 2009 § 2 Comments

In 2004, Stephen Chenney of the University of Wisconsin published a paper in SIGGRAPH Animation titled “Flow Tiles” that brought the idea of terrain editing to scenarios that require objects to flow through a multi-dimensional space.

As part of my Advanced Computer Graphics course (CSE872) at Michigan State University, two classmates and I implemented this paper. Please watch our video below and let me know what you think of it in the comments section (you can compare it to Stephen’s results):

The video was recorded with TechSmith’s Jing Pro and I used a free text-to-speech system called vozMe to create the narrative of the video since I didn’t have a microphone at hand. I then used ffmpeg to merge the audio and video together to create the final output video.

The source code for this project is available at Google Code. If you would like to help reduce some of the technical debt that exists in the code, I would be happy to help you with any questions ;)

Permanently Set the Paragraph Spacing to Single Spaced in Word 2007

19 November, 2009 § 1 Comment

My Dad and others that I know have been constantly frustrated with the change in Microsoft Office Word 2007 to default to 15% larger lines. I’ve tried to help them solve this by creating single spaced templates that default to single spaced, but the workflow for creating a new document based off a template is not obvious nor default.

Today I learned of the best way to revert the behavior back to Office 2003.

I hope this helps others who don’t like the change.

By the way, I do like the change. I find that the text is much easier to read when it has a larger spacing, and studies show I’m not the only one.

Results show that the use of margins affected both reading speed and comprehension in that participants read the Margin text slower, but comprehended more than the No Margin text. Participants were also generally more satisfied with the text with margins. Leading was not shown to impact reading performance but did influence overall user preference.

An interesting take on the Hawthorne Effect

14 June, 2009 § Leave a comment

While I was taking my undergraduate courses at Michigan State for my Bachelor’s of Computer Science, I took a Human-Computer Interaction course taught by Dr. Eileen Kraemer, a visiting scholar from the University of Georgia. In the course, we talked about the Hawthorne Effect and how it can create unintended results during usability studies.

The Hawthorne Effect is based upon research findings that have shown that participants in a study behave differently than normal when they know that their progress is being monitored. Often this comes up in usability studies, as some of the participants results can be questioned to the fact that the user may not have done what they just did had a researcher not been standing next to them. This is one of the major flaws with formal usability research.

To solve this problem, some software will track data anonymously and report it back to the software company. This data can be referenced and presumed to be absent of the Hawthorne Effect since users can be assumed to using the software in their normal ways without feeling like they should perform actions in a different way than normal. Often this is found in prerelease alpha/beta software, but it is becoming more of the norm with final releases where the market of testers expands exponentially.

In the usability realm, the Hawthorne Effect is something that researchers would like to limit. Yet in the project management realm, the Hawthorne Effect is actually something that is strived for.

In Peopleware: Productive Projects and Teams, the authors make a compelling point to try for the Hawthorne Effect on their employees. They claim that changing environment variables in the workplace to provide a better working environment will indeed obtain more work performed by the employees. This change in workplace environment is due to the Hawthorne Effect, since employees will be generally open to the idea (as long as it is not drastic), and will increase their output. Yet this Hawthorne Effect will wear out with time, and so they propose changing up the environment often, and that with this chaos will bring a better return on investment.

I found this approach to the Hawthorne Effect very interesting, since it is a complete reversal of the approach that usability researchers have on the Hawthorne Effect. Instead of trying to minimize the Hawthorne Effect, these project managers are trying to harness it. The Hawthorne Effect was actually coined from some research at Hawthorne Works, a large factory complex outside of Chicago, which was based on changing lighting levels in the workplace and noticing differing levels of increased output.

I wonder why I had never looked at the Hawthorne Effect from this angle before?

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