Month: June 2011

Long-lasting benchmarks

on June 29, 2011

While researching the Top500 list for last week’s blog, I ran across an interesting article (http://bits.blogs.nytimes.com/2011/05/09/the-ipad-in-your-hand-as-fast-as-a-supercomputer-of-yore/?ref=technology). Its basic premise is that the iPad 2 has about the same computing power as the Cray 2 supercomputer, the world’s fastest computer in 1985. I’m old enough to remember the Cray 1 and Cray 2 supercomputers with their unique circular shapes. In their day, they were very expensive and, consequently, rare. Only government agencies could afford to buy them. Just getting to see one was a big deal. In stark contrast, I seem to see iPads everywhere.

What was the benchmark for determining this? It was LINPACK, the same benchmark that determined the winner of the Top500 earlier in June. Based on the LINPACK results, I am holding in my hand a device that could rival the most powerful in the world about 25 years ago. Another perspective is that I have a phone faster than the most powerful computer in the world the year I graduated with my CS degree. And, I use it to play Angry Birds… (Picture trying to convince someone in the 80s that one day millions of hand-held Cray 2 supercomputers would be used to catapult exploding birds at annoying oinking pigs.)

One interesting thought from all of this is the power of benchmarks that last over time. While it will be a rare (and rather limited) benchmark that can last as long as LINPACK, it is important for benchmarks to not change too frequently. On the other side of the scale is the desire for a benchmark to keep up with current technology. With HDXPRT, we are aiming for about a year between versions. I’d love to know whether you think that is too long, too short, or about right.

Bill

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Posted in Benchmarks in general, HDXPRT release cycle, History of benchmarking |

Petaflops?

By Bill Catchings

on June 22, 2011

I saw an article earlier this week about Japan’s K Computer, the latest computer to be designated the “fastest supercomputer” in the world. Twice a year (June and November), the Top500 list comes out. The list’s publishers consider the highest scoring computer on the list as the fastest computer in the world. The first article I read about the recent rankings did not cite the results, just the rankings. So, I went to another article which referred to the K computer as capable of 8.2 quadrillion calculations per second, but did not give the results of the other leading supercomputers. On to the next article which said the K Computer was capable of 1.2 petaflops per second. (The phrase petaflops per second is in the same category as ATM machine or PIN number…) The same article said that the third fastest was able to get 1.75 petaflops per second. OK, now I was definitely confused. (I really miss the old days of good copy editing and fact checking, but that is a blog for another day.)

So, I went to the source, the Top500 Web site (www.top500.org). It confirmed that the K Computer obtained 8.16 petaflops (or quadrillion calculations per second) on the LINPACK test. The Chinese Tianhe-1A got 2.56 petaflops and the American Jaguar, 1.76 petaflops.

Once I got over the sloppy reporting and stopped playing with the graphs of the trends and scores over time, I started thinking about the problem of metrics and the importance of making them easy to understand. Some metrics are very easy to report and understand. For example, a battery life benchmark reports its results in hours and minutes. We all know what this means and we know that more hours and minutes is a good thing. Understanding what petaflops are is decidedly harder.

Another issue is the desire for bigger numbers to mean better results. The time to finish a task is fairly easy to understand, but in that case, less time is better. One technique for dealing with this issue is to normalize the numbers. Basically, that means to divide the result (such as a time) by the result of a baseline system’s result. The baseline system’s result is typically considered to be 1.0 (or some other number like 10 or 100) and other results are meaningful only in relation to the baseline system or each other. A system scoring 2.0 runs twice as fast as the baseline system’s 1.0. While that is clear, it does take more explanation than just seconds.

Finding the right metrics was a challenge we faced with HDXPRT 2011. Do you think we got it right? Please let us know what you think.

Bill

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Posted in Benchmark metrics, HDXPRT metrics |

Knowing when to wait

By Bill Catchings

on June 15, 2011

Mark mentioned in his blog entry a few weeks ago that waiting sucks. I think we can all agree with that sentiment. However, an experience I had while in Taipei for Computex made me reevaluate that thinking a bit.

I went jogging one morning in a park near my hotel. It was a relatively small park, just a quarter mile around the pond that took up most of the park. I was one of only a couple people jogging, but the park was full of people. Some were walking around the pond. There also were groups of people doing some form of Tai Chi in various clearings around the pond. The path I was on was narrow. At times, there was no way of getting around the people walking without running into the ones doing Tai Chi. That in turn meant running in place at times. Or, put another way, waiting.

Everyone was polite at the encounters, but the contrast between me jogging and the folks doing Tai Chi was stark. I wanted to run my miles as quickly as possible. Those doing Tai Chi were decidedly not in a rush. They were doing their exercises together with others. The goal was to do them at the proper pace in the proper way.

That got me to thinking about waiting on my computer. (Hey, time to think is one of the main reasons I exercise!) There are times when waiting for a computer infuriates me. Other times, however, the computer is fast enough. Or even too fast, like when I’m trying to scroll down to the right cell in Excel and it jumps down to a whole screen full of empty cells. This phenomenon, of course, relates to benchmarks. Benchmarks should measure those operations that are slow enough to hurt productivity or are downright annoying. There is less value in measuring operations that users don’t have to wait on.

Have you had any thoughts about what makes a good benchmark? Even if you weren’t exercising when you had the thought, please share it with the community.

Bill

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Posted in Benchmarks in general, HDXPRT metrics, What makes a good benchmark? |

Home sweet home

By Bill Catchings

on June 9, 2011

After a long set of flights back from Computex in Taipei, I’m finally home in North Carolina. Unfortunately, I’m still not quite sure what time zone I’m in!

While awake in the middle of the night, I’ve been thinking about some of the things I saw at Computex. While I was there, it seemed like a jumble of notebooks, power supplies, gaming rigs, motherboards, cases, Hello Kitty accessories, and some things that I still don’t quite know what they were. Many of the things I saw were not brand new, but it was my first chance to see them up close. Some of them were of technologies still on the horizon like Intel’s Ultrabook concept and Microsoft’s Windows 8. I also saw all sorts of combinations of phones, 4G, and other devices.

One thing that stood out to me were the number and variety of tablets. They were in a variety of sizes (and screen resolutions). There were quite a few vendors and some were ones I would not have suspected but was pleasantly surprised to encounter, like Viewsonic and Shuttle. The OS choices included Android, WebOS, and MeeGo. ASUS had a couple of interesting hybrid approaches such as the Eee Pad Transformer and the Padfone. The former is a 10.1-inch tablet that plugs into a keyboard. The Padfone is a smartphone that can plug into the back of a larger (10.1-inch) touch screen to act as a tablet.

All of these tablet choices, as well as the iPad that they all must be compete against, left me wondering how to choose between them. Some part of the choice comes down to the size and features. As always, however, performance plays a key role. My tolerance for waiting on a tablet device is even lower than it is for waiting on my PC. The problem is how to make valid comparisons across such a wide range of platforms. I’d love to hear from you what you think about performance testing on tablets. Is it useful? What are the best ways to accomplish it?

Finally, thanks to all the folks who came by and visited our suite at Computex. I enjoyed getting the chance to meet some of the members of the HDXPRT Development Community. And, hopefully, I convinced more folks to join.

Bill

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Posted in Future of performance evaluation, Performance testing on tablets |

Month: June 2011

Long-lasting benchmarks

Petaflops?

Knowing when to wait

Home sweet home

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