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Green Compiler ?

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  Green Compiler ? Abid <abidmuslim@gmail.com> - 2012-12-20 02:00 -0800
    Re: Green Compiler ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-23 08:18 +0000
      Re: Green Compiler ? Peter Dassow <z80eu@arcor.de> - 2012-12-26 19:31 +0100
        Re: Green Compiler ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-28 03:09 +0000
        Re: Green Compiler ? Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2012-12-28 08:35 +0100
          Re: Green Compiler ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-28 16:14 +0000
          Re: Green Compiler ? Peter Dassow <z80eu@arcor.de> - 2012-12-29 09:35 +0100
            Re: Green Compiler ? Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2012-12-30 08:14 +0100
              Re: Green Compiler ? George Neuner <gneuner2@comcast.net> - 2012-12-31 01:24 -0500
                Re: Green Compiler ? "Jonathan Thornburg" <jthorn@astro.indiana.edu> - 2013-01-02 04:09 +0000
                  Re: Green Compiler ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-02 18:29 +0000
                Re: Green Compiler ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-02 05:11 +0000
                Re: Green Compiler ? Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2013-01-02 07:29 +0100
                  Re: Green Compiler ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-02 19:52 +0000
                    Re: Green Compiler ? "Charles Richmond" <numerist@aquaporin4.com> - 2013-01-04 08:59 -0600
    Re: Green Compiler ? "Nils M Holm" <nmh@t3x.org> - 2012-12-23 10:01 +0100
      Re: Green Compiler ? Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2012-12-24 05:16 +0100
      Re: Green Compiler ? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-12-27 13:36 +0000
        Re: Green Compiler ? "Nils M Holm" <nmh@t3x.org> - 2012-12-28 09:11 +0100
          Re: Green Compiler ? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-12-28 16:57 +0000
          Re: Green Compiler ? George Neuner <gneuner2@comcast.net> - 2012-12-28 12:57 -0500
            Re: Green Compiler ? "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2012-12-30 09:22 +0100
      Re: Green Compiler ? Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-12-27 21:59 -0600
    Re: Green Compiler ? Walter Banks <walter@bytecraft.com> - 2012-12-28 10:42 -0500

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#817

On Fri, 28 Dec 2012 09:11:23 +0100, "Nils M Holm" <nmh@t3x.org> wrote:

>Why does a game *have to* use the maximum number of frames per
>second? When a given number of frames per second is sufficient,
>in the sense that additional frames will not make the video output
>any smoother, why increase the frame rate further?

Unfortunately, games are hardly the only offenders.  When I worked in
medical imaging (circa mid 90's), there was a requirement to render
cineloops at 66fps regardless of image size, pixel depth or 2D vs 3D
processing.  There were no 3-D GPUs and SIMD CPUs of the day
(UltraSparc, Pentium MMX, etc.) were not equal to many of the imaging
tasks.  We had to use custom FPGA based hardware to achieve the
required frame rates at a (halfway) reasonable (to the user) cost.

AFAIA, medical cineloops still are required to be rendered at 66fps.
Doesn't matter that 40fps is faster than almost any human can see.

George

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#823

On Fri, 28 Dec 2012 12:57:52 -0500, George Neuner wrote:

> On Fri, 28 Dec 2012 09:11:23 +0100, "Nils M Holm" <nmh@t3x.org> wrote:
>
>>Why does a game *have to* use the maximum number of frames per
>>second? When a given number of frames per second is sufficient,
>>in the sense that additional frames will not make the video output
>>any smoother, why increase the frame rate further?
>
> Unfortunately, games are hardly the only offenders.  When I worked in
> medical imaging (circa mid 90's), there was a requirement to render
> cineloops at 66fps regardless of image size, pixel depth or 2D vs 3D
> processing.  There were no 3-D GPUs and SIMD CPUs of the day
> (UltraSparc, Pentium MMX, etc.) were not equal to many of the imaging
> tasks.  We had to use custom FPGA based hardware to achieve the
> required frame rates at a (halfway) reasonable (to the user) cost.
>
> AFAIA, medical cineloops still are required to be rendered at 66fps.
> Doesn't matter that 40fps is faster than almost any human can see.

I thought it so, but it seems urban legend. In late 90's I worked in a
project that in particular rendered waveforms (electrocardiogram). It was a
huge problem then as it required to run on a conventional PC. There was no
specific fps specification, but requirement that curves scrolled smoothly
to human eye. Experiments shown that only at 10ms refresh rate you stop
noticing curve's jitter.

Maybe there is some relation to aliasing issues. Certainly the brain needs
much more time for 3D scenes than for simple geometric shapes. And it is
probably way different for LED displays now than for tubes then.

--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

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#810

On 12/23/2012 3:01 AM, Nils M Holm wrote:
> Abid <abidmuslim@gmail.com> wrote:
>> Do we need to change this model and make it
>> three dimensional by adding power axis in the search space?
>
> In principle, I would say that higher execution speed equals more
> grenn-ness. Less time spent dissipating heat means less energy
> consumed.

Power consumption of hardware scales quadratically with respect to
frequency. If you can stand doing computation at lower frequency
scales (at, say, 600 MHz), you will lose far less energy than doing
the equivalent computation at the maximum frequency scale (say, 3
GHz).

In general, minimizing power consumption means utilizing all
components of your computer most effectively. In current homogeneous
computers, the question is rather moot (choice of frequency and cores
to run is a decision of the operating system, and compilers generally
cannot affect this decision. However, the future of computers seems to
be increasing utilization of heterogeneous computation, at which point
we're at a point where research into ways of designing code that can
take advantage of various unconventional hardware (DSPs, GPUs, etc.)
is still ongoing.

--
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth

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#814

Abid wrote:

> Hi:
>
> It seems that the Power Wall is becoming a major  issue, especially for High
> Performance Computing. Current compilers work has two dimensional model, i.e.,
> all the optimization phases are targeted either towards reducing execution
> time or code size. My question is: Do we need to change this model and make it
> three dimensional by adding power axis in the search space? If yes, then we
> have to revisit all the phases and adjust them or come up with  new cost
> models for these phases.
>
> I will be grateful if some one can point me to the latest efforts/projects
> with respect to power efficient compilation for high performance computing.

There has been a lot of work on energy efficient compiling. In the 80's
were were working on a data logging project where the devices needed to
run on battery power unattended for for more than a year in very bad
environments.

We created a compiler (CMOS variant to the Motorola 6805) to do the
development work initially optimized to require minimum execution
cycles.  As the project evolved we refined our model of the power
profile of the processor and made design modifications to product to
reduce energy consumption.

Our models started to look at both number of RAM and ROM fetches and
RAM writes as well as cycle counts. RAM and ROM access were separately
characterized.

We focused on utilizing page0 zero memory accesses and switching
external memory from sleep to active mode and minimizing the time each
memory was active.


The accumulation of the various optimizations made a big difference
to the energy consumption of the application.


Walter Banks

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