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Subject: Re: Introducing "No-Moore's Law"

Author: Robert Hyatt

Date: 20:58:37 03/08/03

Go up one level in this thread


On March 08, 2003 at 14:52:02, Jeremiah Penery wrote:

>On March 08, 2003 at 01:37:18, Robert Hyatt wrote:
>
>>On March 08, 2003 at 00:42:23, Matt Taylor wrote:
>>
>>>On March 07, 2003 at 23:37:24, Robert Hyatt wrote:
>>>
>>>>That's the point.  Yes, I suppose you could make a case that anybody should
>>>>read the docs before they use the product.  But in reality, you know that
>>>>nobody does, because the assumption is that all vehicles use currently available
>>>>unleaded fuel unless great big warning signs are everywhere...
>>>
>>>Your analogy is flawed at the core. A better analogy would be condemning
>>>Plymouth for releasing an automobile with a big sign on the side that says,
>>>"Leaded fuel," when it breaks after the owner puts in unleaded gasoline. The K6
>>>has a big stamp on it called CPUID that says, "I can't do cmovcc."
>>
>>It doesn't have a "big stamp" which is the problem.  It has a Big Stamp that
>>says "X86 compatible".  And back on page 400 you discover "but the cmovxx
>>instructions are not implemented in this processor."
>>
>>What is a "big stamp" to you is a fine-print disclaimer buried on page 400 to
>>a "grandmother program developer."  :)
>
>You don't even have to look at the manual for this.  It's like the car scenario,
>where if you tried to put unleaded gas in the leaded car, a voice came out of
>the gas tank and said, "I don't run on unleaded gas!"  The processor tells you
>it doesn't support CMOV.  It's your fault if you still try to use it.

It really does _not_ say that.   I compile with target=PII.  I send the
executable to some friend.  He runs it and it says "segmentation violation"
and dumps core.

>
>>>>I saw them sitting side-by-side in comp USA.  With signs saying "Built with
>>>>an AMD inside."  And magazine adds hanging in front of them showing the infamous
>>>>"faster but cheaper".  If they are put side by side, and even AMD compared
>>>>price and performance, it is certainly _reasonable_ to consider them to be
>>>>compatible.  After all, nobody compares a gas automobile to a diesel auto
>>>>without _explicitly_ pointing out the pros/cons of the non-standard fuel.
>>>
>>>Dell sells Pentium 3 systems side-by-side with Pentium 4 systems.
>>
>>Notice anything different?  Pentium 3.  Pentium 4.  They _clearly_ identify
>>what is "inside" is a pentium-X.  That's a bit different than just selling
>
>The AMD machines _clearly_ identified that they were, in fact, AMD machines too,
>so I'm not sure what you're getting at.



And if you go back to that point in time and look at various computing
journals, magazines and so forth, you will clearly find ads that said
"Buy AMD.  Its faster than a PII, and cheaper.  Here are the benchmark
results that show this..."

What should I (as a naive user) conclude from that?  That it is faster
and cheaper _and_ incompatible?  Then why didn't they say "it is faster
than a pentium II, faster than a hairdryer, and faster than a Nintendo
N64"???  The conclusion about "faster than a PII" certainly implies that
it is also _compatible_.




>
>>something that is compared to the pentium II in your own ads, but which is
>>not quite a pentium-II in fact...
>
>By selling them side-by-side, Dell is comparing them.  But Pentium3 is not quite
>a Pentium4 in fact...


And nobody assumes that.  But clearly if someone compares a chip to a PII,
the implication is that they are equivalent.  Otherwise the comparison is
not very informative.




>
>>99% of crafty users don't have any idea how to compile the thing...
>
>And probably 99% of that group of people is using Windows, so they use the
>executable that runs on all processors.  It's a non-issue for them.
>

Not when we were supplying "plain executables" and executables compiled
specifically for the PII.  That was my point.  The release notes used to
explain the different versions (SMP, non-SMP, and specific architecture
assumptions.)  IE Dann has executables optimized for all sorts of platforms.

It was the _users_ that assumed that PII = K6 since AMD magazine publicity
certainly implied it if not outright claimed it.




>
>BTW, I'm still waiting for those SPARC/MIPS benchmark numbers, as well as the
>SPARC sales numbers.

SPARC is a problem.  I have tried 3 gcc versions and all produce bad code for
recent versions of Crafty, reasons = unknown.  I have some very old SPARC
numbers but they are useless.  I have tried installing the latest 3.2 gcc
version, and my reliable (for Intel) 2.95.2, and 2.95.5.  If I can't get
good executables then I can't compare 'em.  Didn't even try the SGI (I think
we have two 600mhz machines here, not sure if we have anything faster as I
am not an SGI/MIPS "person".  But something is bad on the sparc.  It runs with
no optimization, but that's a useless comparison.  It crashes with -O or
anything beyond (O3, etc.)







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