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Re: fast arithmetic hardware, was These days what percentage of a CPU's work involves doing arithmetic computations

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On Thu, 15 Jul 2021 23:49:55 -0700 (PDT), gah4 <gah4@u.washington.edu>
wrote:

>There is pretty much a continuous change, as processors get faster,
>then less efficient processing makes more sense.
>Among others, less efficient, interpreted languages have become
>more popular.
>
>It is interesting, though.  For much of the 1990's, faster and faster
>processor became available for compute intensive applications like
>computational physics, but mostly driven by demand from other uses.
>
>Some of that was people who bought faster processors because they
>could, and some by gaming.  For the most part, processors haven't been
>built for compute intensive use from about the 1990's.
>
>In the 1980's, there were some coprocessor to speed up compute intensive
>problems, such as FPS (Floating Point Systems).  But as desktop computers,
>and especially x86 machines, got faster there was less need for them.
>
>And then GPUs to speed up graphics, mostly for games, but then compute
>intensive users found that they could use them, too.  Except that most are only
>single precision.

But processors /aren't/ getting faster (much) anymore - they're near
the limits both of feature size reduction and of ability to dissipate
heat.

The wires and insulators now are just a few atoms thick, and since
there are insulators /inside/ transistors, the transistors themselves
can't get much smaller [they can change shape, which is how things are
progressing currently].

Modern CPUs live in a perpetual state of "rolling blackout" in which
functional units are turned on and off, cycle by cycle, as needed.
This is /NOT/ done for "green" minded energy conservation [that's just
self serving PR by the manufacturers] - it's /necessary/ to prevent
the chips from burning up.


And GPUs are /very/ slow relative to CPUs.  The only reason they seem
to perform well is because the problems they target are embarrassingly
parallel.  Try solving a problem that requires lots of array reduction
steps and you'll see your performance go straight into the toilet.
[Yes, I know that there are tree methods for parallelizing reductions
... they are not always straightforward to implement, and they only
work for /some/ reduction problems.]


I have worked with Connection Machines (CM-2), DSPs, FPGAs, and I have
written a lot of SIMD code for image and array processing tasks.  I am
well aware of what is possible using various styles of parallel
processing.  There's a lot that can be done ... and a lot /more/ that
can't: the vast majority of all computing problems do not have any
known parallel solutions.

It's true that there is a lot of instruction level (micro-thread)
parallelism available in most programs.  It is dificult to exploit
with current hardware.  This is a topic frequently discussed in
comp.arch.

YMMV,
George

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These days what percentage of a CPU's work involves doing arithmetic computations versus other, non-arithmetic computations? Roger L Costello <costello@mitre.org> - 2021-07-14 18:30 +0000
  Re: These days what percentage of a CPU's work involves doing arithmetic computations versus other, non-arithmetic computations? gah4 <gah4@u.washington.edu> - 2021-07-15 02:31 -0700
    Re: These days what percentage of a CPU's work involves doing arithmetic computations versus other, non-arithmetic computations? Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2021-07-15 22:02 +0200
    Re: These days what percentage of a CPU's work involves doing arithmetic computations versus other, non-arithmetic computations? "Robin Vowels" <robin51@dodo.com.au> - 2021-07-16 14:47 +1000
    Re: fast arithmetic hardware, was These days what percentage of a CPU's work involves doing arithmetic computations gah4 <gah4@u.washington.edu> - 2021-07-15 23:49 -0700
      Re: fast arithmetic hardware, was These days what percentage of a CPU's work involves doing arithmetic computations George Neuner <gneuner2@comcast.net> - 2021-07-16 16:22 -0400
  Re: These days what percentage of a CPU's work involves doing arithmetic computations versus other, non-arithmetic computations? "Robin Vowels" <robin51@dodo.com.au> - 2021-07-16 15:12 +1000
    Re: ancient floating point, These days what percentage of a CPU's work involves doing arithmetic computations Philipp Klaus Krause <pkk@spth.de> - 2021-07-16 18:31 +0200
      Re: ancient floating point, These days what percentage of a CPU's work involves doing arithmetic computations Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2021-07-17 23:14 +0200
  Re: These days what percentage of a CPU's work involves doing arithmetic computations versus other, non-arithmetic computations? Derek Jones <derek@NOSPAM-knosof.co.uk> - 2021-07-19 15:35 +0100
  Re: These days what percentage of a CPU's work involves doing arithmetic computations versus other, non-arithmetic computations? "minf...@arcor.de" <minforth@arcor.de> - 2021-07-27 14:07 -0700

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