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'Approximate Computing' Saves Energy

Posted by Soulskill on from the 1+1=3-for-sufficiently-large-values-of-1 dept.

hessian writes "According to a news release from Purdue University, 'Researchers are developing computers capable of "approximate computing" to perform calculations good enough for certain tasks that don't require perfect accuracy, potentially doubling efficiency and reducing energy consumption. "The need for approximate computing is driven by two factors: a fundamental shift in the nature of computing workloads, and the need for new sources of efficiency," said Anand Raghunathan, a Purdue Professor of Electrical and Computer Engineering, who has been working in the field for about five years. "Computers were first designed to be precise calculators that solved problems where they were expected to produce an exact numerical value. However, the demand for computing today is driven by very different applications. Mobile and embedded devices need to process richer media, and are getting smarter – understanding us, being more context-aware and having more natural user interfaces. ... The nature of these computations is different from the traditional computations where you need a precise answer."' What's interesting here is that this is how our brains work."

12 of 154 comments (clear)

  1. Analog by Nerdfest · · Score: 5, Interesting

    This is also how analog computers work. They're extremely fast and efficient, but imprecise. It had a bit of traction in the old days, but interest seems to have died off.

  2. Accuracy isn't important anymore by EmagGeek · · Score: 4, Insightful

    We're teaching our kids that 2+2 equals whatever they feel it is equal to, as long as they are happy. What do we need with accuracy anymore?

  3. Numerical computation is pervasive by l2718 · · Score: 4, Informative

    This is not about data centers and databases. This is about scientific computation -- video and audio playback, physics simulation, and the like.

    The idea of doing a computation approximately first, and then refining the results only in the parts where more accuracy is useful is an old idea; one manifestation are multigrid algorithms.

    1. Re:Numerical computation is pervasive by raddan · · Score: 5, Interesting

      Not to mention floating-point computation, numerical analysis, anytime algorithms, and classic randomized algorithms like Monte Carlo algorithms. Approximate computing has been around for ages. The typical scenario is to save computation, nowadays expressed in terms of asymptotic complexity ("Big O"). Sometimes (as is the case with floating point), this tradeoff is necessary to make the problem tractable (e.g., numerical integration is much cheaper than symbolic integration).

      The only new idea here is using approximate computing specifically in trading high precision for lower power. The research has less to do with new algorithms and more to do with new applications of classic algorithms.

  4. Been there by frovingslosh · · Score: 4, Funny

    I remember Intel doing something like this back in the days of the 386, except without the energy savings.

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  5. Fuzzy Logic anyone? by kbdd · · Score: 4, Informative
    Fuzzy logic was also supposed to save energy (in the form of requiring less advanced processors) by replacing computation intensive closed loop systems with table driven approximate logic.

    While the concept was interesting, it did not really catch up. Progress of silicon devices made it simply unnecessary. It ended up being used as a buzz word for a few years and quietly died away.

    I wonder if this is going to follow the same trend.

  6. Re:meanwhile... by ron_ivi · · Score: 4, Informative

    The majority of CPU cycles in data centers is going to be looking up and filtering specific records in database

    Approximate Computing is especially interesting in databases. One of the coolest projects in this space is Berkeley AMPLab's BlinkDB. Their cannonical example

    SELECT avg(sessionTime) FROM Table WHERE city='San Francisco' ERROR 0.1 CONFIDENCE 95%

    should give you a good idea of how/why it's useful.

    Their bencmarks show that Approximate Computing to 1% error is about 100X faster than Hive on Hadoop.

  7. Re:meanwhile... by lgw · · Score: 5, Funny

    Currently Slashdot is displaying ads for me along with the "disable ads" checkbox checked. Perhaps "approximate computing" is farther along than I imagined!

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    Socialism: a lie told by totalitarians and believed by fools.
  8. Re:meanwhile... by ron_ivi · · Score: 4, Informative
    Better - more technical link/paper that explains it in more detail: http://www.cs.berkeley.edu/~sameerag/blinkdb_eurosys13.pdf

    DB: Queries with Bounded Errors and Bounded Response Times on Very Large Data

  9. Computation is not the big energy drain by Ottibus · · Score: 4, Interesting

    The problem with this approach is that the energy used for computation is a relatively small part of the whole. Much more energy is spent on fetching instructions, decoding instructions, fetching data, predicting branches, managing caches and many other processes. And the addition of approximate arithmetic increases the area and leakage of the processor which increases engergy consumption for all programs.

    Approximate computation is already widely used in media and numerical applications, but it is far from clear that it is a good idea to put approximate arithmetic circuits in a standard processor.

  10. Re:meanwhile... by formfeed · · Score: 5, Funny

    Currently Slashdot is displaying ads for me along with the "disable ads" checkbox checked. Perhaps "approximate computing" is farther along than I imagined!

    Sorry, that was my fault. I didn't have my ad-block disabled. They must have sent them to you instead.
    Just send them to me and I will look at it.

  11. Clive SInclair did this in 1974. by hamster_nz · · Score: 4, Informative

    Due to ROM and cost limitations the original Sinclair Scientific calulator only produced approximate answers, maybe to 3 or four digits.
    This was far more accurate than the answers given by a slide rule....

    For more info have a look at this page Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35