Thursday, May 17th 2012

Computing Experts Unveil Superefficient ‘Inexact’ Chip

Researchers have unveiled an “inexact” computer chip that challenges the industry’s 50-year pursuit of accuracy. The design improves power and resource efficiency by allowing for occasional errors. Prototypes unveiled this week at the ACM International Conference on Computing Frontiers in Cagliari, Italy, are at least 15 times more efficient than today’s technology.

The research, which earned best-paper honors at the conference, was conducted by experts from Rice University in Houston, Singapore’s Nanyang Technological University (NTU), Switzerland’s Center for Electronics and Microtechnology (CSEM) and the University of California, Berkeley.

“It is exciting to see this technology in a working chip that we can measure and validate for the first time,” said project leader Krishna Palem, who also serves as director of the Rice-NTU Institute for Sustainable and Applied Infodynamics (ISAID). “Our work since 2003 showed that significant gains were possible, and I am delighted that these working chips have met and even exceeded our expectations.”

ISAID is working in partnership with CSEM to create new technology that will allow next-generation inexact microchips to use a fraction of the electricity of today’s microprocessors.

“The paper received the highest peer-review evaluation of all the Computing Frontiers submissions this year,” said Paolo Faraboschi, the program co-chair of the ACM Computing Frontiers conference and a distinguished technologist at Hewlett Packard Laboratories. “Research on approximate computation matches the forward-looking charter of Computing Frontiers well, and this work opens the door to interesting energy-efficiency opportunities of using inexact hardware together with traditional processing elements.”

The concept is deceptively simple: Slash power use by allowing processing components — like hardware for adding and multiplying numbers — to make a few mistakes. By cleverly managing the probability of errors and limiting which calculations produce errors, the designers have found they can simultaneously cut energy demands and dramatically boost performance.

One example of the inexact design approach is “pruning,” or trimming away some of the rarely used portions of digital circuits on a microchip. Another innovation, “confined voltage scaling,” trades some performance gains by taking advantage of improvements in processing speed to further cut power demands.

In their initial simulated tests in 2011, the researchers showed that pruning some sections of traditionally designed microchips could boost performance in three ways: The pruned chips were twice as fast, used half as much energy and were half the size. In the new study, the team delved deeper and implemented their ideas in the processing elements on a prototype silicon chip.

“In the latest tests, we showed that pruning could cut energy demands 3.5 times with chips that deviated from the correct value by an average of 0.25 percent,” said study co-author Avinash Lingamneni, a Rice graduate student. “When we factored in size and speed gains, these chips were 7.5 times more efficient than regular chips. Chips that got wrong answers with a larger deviation of about 8 percent were up to 15 times more efficient.”

Project co-investigator Christian Enz, who leads the CSEM arm of the collaboration, said, “Particular types of applications can tolerate quite a bit of error. For example, the human eye has a built-in mechanism for error correction. We used inexact adders to process images and found that relative errors up to 0.54 percent were almost indiscernible, and relative errors as high as 7.5 percent still produced discernible images.”

Palem, the Ken and Audrey Kennedy Professor of Computing at Rice, who holds a joint appointment at NTU, said likely initial applications for the pruning technology will be in application-specific processors, such as special-purpose “embedded” microchips like those used in hearing aids, cameras and other electronic devices.

The inexact hardware is also a key component of ISAID’s I-slate educational tablet. The low-cost I-slate is designed for Indian classrooms with no electricity and too few teachers. Officials in India’s Mahabubnagar District announced plans in March to adopt 50,000 I-slates into middle and high school classrooms over the next three years.

The hardware and graphic content for the I-slate are being developed in tandem. Pruned chips are expected to cut power requirements in half and allow the I-slate to run on solar power from small panels similar to those used on handheld calculators. Palem said the first I-slates and prototype hearing aids to contain pruned chips are expected by 2013.

This comparison shows frames produced with video-processing software on traditional processing elements (left), inexact processing hardware with a relative error of 0.54 percent (middle) and with a relative error of 7.58 percent (right). The inexact chips are smaller, faster and consume less energy. The chip that produced the frame with the most errors (right) is about 15 times more efficient in terms of speed, space and energy than the chip that produced the pristine image (left).Source: Rice.edu
Add your own comment

51 Comments on Computing Experts Unveil Superefficient ‘Inexact’ Chip

#1
btarunr
Editor & Senior Moderator
by: btarunr
Officials in India’s Mahabubnagar District
Hehe, that place is 30 km south of here.
Posted on Reply
#2
Edgarstrong
They went all the way to Sardinia to unveil it?
Posted on Reply
#3
Fourstaff
by: Edgarstrong
They went all the way to Sardinia to unveil it?
No, they didn't go to Sardinia to unveil it. Rather, they gave themselves a holiday packaged as a conference, and decided that they should show the world their new toy while having their holiday.
Posted on Reply
#4
mcloughj
That's all well and good when processing video but it'll be completely useless for science!
Posted on Reply
#5
theoneandonlymrk
by: btarunr
Hehe, that place is 30 km south of here.
cheers for the read, you gota be the man for any new goss on that then , im all ears if theres more in the future, could be an explosive development for low end device costs etc
Posted on Reply
#6
Steevo
by: mcloughj
That's all well and good when processing video but it'll be completely useless for science!
How many use their smartphone for science, and even if it were to run applications they probably allow for exact processing.

Much like writing a 64 bit transaction into a 16 bit register by rounding the result to fit.
Posted on Reply
#7
OneCool
Damn that dude is creepy looking.
Posted on Reply
#9
Divide Overflow
by: OneCool
Damn that dude is creepy looking.
InExcatly!
Posted on Reply
#10
Static~Charge
by: btarunr
Researchers have unveiled an “inexact” computer chip that challenges the industry’s 50-year pursuit of accuracy. The design improves power and resource efficiency by allowing for occasional errors.
So, it gets the wrong answer faster? :wtf:
Posted on Reply
#11
theoneandonlymrk
by: Static~Charge
So, it gets the wrong answer faster?
i had one o them till it blew up, it got to the wrong answer quite often, and quite quickly near the end:)
Posted on Reply
#12
AphexDreamer
Pretty cool to think a College so close to me is doing revolutionary work that could move the world forward.

Stupid University of Houston, we just went tier 1 and all it did was raise my tuition.

That pic reminds me of how pictures would load on my 26kbps internet connection back in the day.
Posted on Reply
#13
Steven B
yea i would personally rather pay for 100% accuracy, that is how the normal consumer will see it i think. Cool concept tho. I went to Georgia Tech, yea it is pretty cool to be at a university that does a lot of ground breaking stuff.
Posted on Reply
#14
Completely Bonkers
Great for video. Not good for bank accounts. Horses for courses. I'd be OK with a GPU using this... if I could get better performance at lower power with no noticeable loss of quality. But I wouldn't want my CUDA card giving me approximately the right answer sometimes!
Posted on Reply
#15
Liquid Cool
So...this chip mimics real life?

:laugh:

I'd buy one.

LC
Posted on Reply
#16
james888
I could certainly see this having some uses
Posted on Reply
#17
KieranD
Wouldn't that cause glitches, errors and crashes?
Posted on Reply
#18
LAN_deRf_HA
by: Completely Bonkers
Great for video. Not good for bank accounts. Horses for courses. I'd be OK with a GPU using this... if I could get better performance at lower power with no noticeable loss of quality. But I wouldn't want my CUDA card giving me approximately the right answer sometimes!
Great for video? Did you see that example image? Even half a percent was atrocious. I'm sure they can find some corner of the digital world where this is useful but keep this junk out of my PC.
Posted on Reply
#19
HalfAHertz
We'd need all new software that was suited to these small errors and deviations, because our current software just needs the wind the blow in the wrong way to cause it to crash.
Posted on Reply
#20
AphexDreamer
by: HalfAHertz
We'd need all new software that was suited to these small errors and deviations, because our current software just needs the wind the blow in the wrong way to cause it to crash.
lol yeah.. It would be interesting to know how one's code would be changed to accommodat such errors. Sounds almost as interesting if not more than the actual chip itself no?
Posted on Reply
#21
MikeMurphy
Small errors are fine when it comes to things like audio and video depending on how its processed. You wouldn't even notice the difference.

Regular code however wouldn't be run on that part of the chip.

Its ideal for smartphone and netbook A/V use. Would quite handily allow decoding of 4k content.
Posted on Reply
#22
sergionography
i dont see this approach as the way to go in the future, however i think if future chips allow for this to be among the features that you could enable/disable for higher performance then it is very impressive
in GPUs especially it could be handy along with amds and nvidias inhouse AA implementations(txaa, fxaa and others)
Posted on Reply
#23
Darkrealms
So am I the only one that first thought: very fast processing + variable inaccuracy = illogical AI
Here comes terminator?
Posted on Reply
#24
jamsbong
How is this different from a flawed CPU?
Posted on Reply
#25
Jacez44
I don't think you guys understand.

The premise is that it gets a SLIGHTLY inaccurate result VASTLY more quickly.
Posted on Reply
Add your own comment