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Re: IBM demos cognitive computer chips

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On 8/21/2011 2:56 PM, BGB wrote:

> AMD Fusion is cool, although too bad the GPU's don't run something more
> x86-like, as this could allow interesting possibilities. it may take
> several generations though before the technology gets "more cool".

There is little reason why the GPU/SIMD/SIMT/coherent threading hardware 
could not be running any reasonable instruction set.  Possibly including 
x86 or ARM.

I hesitate to say "GPU", since if you really wanted graphics you would 
have to extend the ISA quite a bit.  But if all you wanted was GPGPU, 
almost any ISA would do.

Note that the basic effect f GPU-style SIMD/SIMT/Coherent threading is 
to amortize instruction decode over more compute.  You still may not 
want to waste area on x86 decoding, but the net lossage is reduced. 
Also, GPU-stye encourages non-superscalar decoding, and decoding x86 one 
instruction at a time is much better than sperscalar x86 decode.

If I had known about coherent threading when I was at AMD, I would have 
proposed that the multi-cluster multi-threading that seems to be in 
Bulldozer be "opportunistically coherent", running GPU-style 
SIMD/SIMT/coherent instruction fetch when the threads were executing the 
same loop.

However: it is not at all clear to me that x86 has much advantage any 
longer.  Of course, Intel and to a lesser extent AMD want you to believe 
that x86 still matters, and it probably does for laptops and servers, 
but x86 probably would not matter mauch for cell phones - ARM 
compatibility matters more there - and there may be a brief window where 
there is an opportunity for non-x86 non-ARM ISAs to break through.





> although, it is potentially a reasonable tradeoff, as potentially if it
> were just x86, then compiler writers would likely stick to conventions
> which as-is make threading rather costly on normal systems:
> using a single large dedicated per-thread stack.
>
> the use of individual/independent frames would allow more economical use
> of memory and address space.
>
> granted, people could also argue "well, we have 64 bits now, why not
> just give each thread its own 4MB or 8MB (or more) stack? (CPS/... is
> for wimps...)".

This is one of the keys:

Interleaved stacks for when operating in lockste, or nearly so.

Uninterleaved stacks for MIMD parallel.

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IBM demos cognitive computer chips Brett Davis <ggtgp@yahoo.com> - 2011-08-18 18:02 -0500
  Re: IBM demos cognitive computer chips EricP <ThatWouldBeTelling@thevillage.com> - 2011-08-18 20:37 -0400
    Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-19 13:40 -0400
      Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-19 11:52 -0700
        Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-19 15:50 -0400
          Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-20 00:15 -0700
            Re: IBM demos cognitive computer chips Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-08-20 09:22 -0700
              Re: IBM demos cognitive computer chips EricP <ThatWouldBeTelling@thevillage.com> - 2011-08-20 14:10 -0400
        Re: IBM demos cognitive computer chips Quadibloc <jsavard@ecn.ab.ca> - 2011-08-21 05:16 -0700
          Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-21 11:56 -0700
            Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-21 15:29 -0400
              Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-21 13:19 -0700
            Re: IBM demos cognitive computer chips "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-08-22 09:41 -0400
              Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-22 12:22 -0700
                Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-22 13:01 -0700
              Re: IBM demos cognitive computer chips "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-08-23 10:11 -0400
              Re: IBM demos cognitive computer chips Eric  Northup <digitaleric@gmail.com> - 2011-08-23 09:36 -0700
                Re: IBM demos cognitive computer chips "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-08-24 22:15 -0400
                Re: IBM demos cognitive computer chips "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-08-25 09:07 -0400
      Re: IBM demos cognitive computer chips EricP <ThatWouldBeTelling@thevillage.com> - 2011-08-20 01:41 -0400
      Re: IBM demos cognitive computer chips Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-08-20 08:55 -0700
        Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-20 16:10 -0400
          Re: IBM demos cognitive computer chips Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-08-21 21:11 -0700
            Re: IBM demos cognitive computer chips EricP <ThatWouldBeTelling@thevillage.com> - 2011-08-22 12:04 -0400
              Re: IBM demos cognitive computer chips EricP <ThatWouldBeTelling@thevillage.com> - 2011-08-22 12:22 -0400
            Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-22 14:24 -0400
              Re: IBM demos cognitive computer chips Quadibloc <jsavard@ecn.ab.ca> - 2011-08-22 19:32 -0700
                Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-22 23:21 -0700
                Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-23 09:49 -0700
                Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-23 09:46 -0700
                Re: IBM demos cognitive computer chips BGB <cr88192@hotmail.com> - 2011-08-23 15:05 -0700
                Re: IBM demos cognitive computer chips Piotr Wyderski <peter.pan@neverland.mil> - 2011-08-26 16:04 +0200
                Re: IBM demos cognitive computer chips Quadibloc <jsavard@ecn.ab.ca> - 2011-08-26 09:58 -0700
                Re: IBM demos cognitive computer chips ChrisQ <meru@devnull.com> - 2011-08-29 14:56 +0100
                Re: IBM demos cognitive computer chips EricP <ThatWouldBeTelling@thevillage.com> - 2011-08-29 11:06 -0400
                Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-29 16:10 -0400
                Re: IBM demos cognitive computer chips EricP <ThatWouldBeTelling@thevillage.com> - 2011-08-29 17:48 -0400
                Re: IBM demos cognitive computer chips Robert Myers <rbmyersusa@gmail.com> - 2011-08-29 19:24 -0400
    Re: IBM demos cognitive computer chips ggtgp@yahoo.com - 2012-03-30 21:54 -0700

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