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Subject: Re: Opteron very fast at 64 bits

Author: Vincent Diepeveen

Date: 08:12:15 08/03/03

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On August 03, 2003 at 06:14:06, Bo Persson wrote:

>On August 02, 2003 at 18:22:58, Vincent Diepeveen wrote:
>
>>On August 02, 2003 at 09:15:26, Bo Persson wrote:
>>
>>>On August 01, 2003 at 14:13:18, Kim Roper Jensen wrote:
>>>
>>>>On August 01, 2003 at 14:00:18, Eugene Nalimov wrote:
>>>>
>>>>>I see quite different result on AMD64 when Crafty is compiled by 64-bit Visual
>>>>>C. :-)
>>>>>
>>>>>Thanks,
>>>>>Eugene
>>>>>
>>>>
>>>>Sorry for asking but what did you see ?? :)
>>>
>>>
>>>A non-disclosure agreement in his employment contract?  :-)
>>>
>>>I'm sure we will see the numbers about 2 seconds after the compiler is released.
>>
>>Not really. What you need first is a windows version that can run the stuff 64
>>bits native at opteron.
>
>Yes, of course. Do you care to make a guess on what MS is using their Opteron
>compiler for. :-)

I guess they are working hard and basic problem is not only that m$ is 32 bits
in some respects (file systems and such already long period ago 64 bits in 1995)
but especially that their kernel stuff is written in assembly.

That's one of the reasons why the kernel is much faster practically than linux
for applications (if i put of old diep versions which aren't NUMA 2 processes to
search at a single cpu machine then it runs *way* faster on NT, about factor 2
to 4 than under linux kernel).

So using their own compiler for their own kernel is not exactly what they can
do.

A big challenge of opteron is that it is NUMA.

I am sure m$ will be very happy supporting the AMD platforms. Competition in the
hardware branche is good for microsoft. So in the highest levels of the
organisations the x86-64 platforms will have a lot of support.

Even if microsoft wouldn't want to support it, they still MUST support it
because x86 is history within a few years and we all will be running x86-64
platforms only. Either with intel OR amd sticker.

I guess even the biggest cpu amateurs will understand by now that intel is
developing their own x86-64 processor generations. Perhaps even giving it a 'p4'
sticker though it's an entirely new core.

The only thing we do not know is *when* they will release their x86-64 cpu's.
AMD simply has advantage there now.

We can very shortly describe the x86-64 architecture. Cheap. High clockable and
superior to everything out there including itanium. Especially superior to
itanium.

I'm running at a cpu or 64 now (itanium2-madison 1.3Ghz 3MB) and they are great
for the highend but a joke even when compared to x86 for the average user.

Intel plans to mass produce itaniums for the 'low-end' market have been put into
the fridge a long while ago. The only reason intel is continuing this processor
now (seemingly) is because they probably can't go back. Or perhaps they wait
until they have x86-64 cpu's available.

How can GCC 2.96 without profile recompilation be just 15% slower than intel c++
7.0 using profile information (prof_use) at the itanium platform?

The problem of the itanium platform is they can't clock it high despite working
for years already at that problem, it is too expensive, and it is impossible to
write software for it.

Even the current generations of supercomputers with itaniums that get delivered
are missing major software support for it. Like crucial fortran libraries.

This where > 60% of the total system time of supercomputers goes to gflops used
by fortran libraries.

If you add up the picture then it is a matter of time before the x86-64 will
dominate everything.

However it is sad to realize that most likely the linux world will be too late
again. Despite that microsoft must convert their assembly libraries to new
opteron assembly, we know they must be very far already with that conversion.

This where the linux plans to write a NUMA kernel for kernel 2.6 have been just
defined a few weeks ago. Not to mention the years it will take to carry out an
effective implementation.

For those who still do not understand what i'm talking about. When you have more
than 1 opteron processor, so a dual opteron or even more processors, then it is
of crucial importance that the kernel can run locally on each kernel for the
jobs that can be done locally.

Local memory at opteron is way faster than global memory.

In fact the opteron asks for a cc-NUMA operating system which until recently was
only getting used by very big non-real time supercomputer systems.

I would not be surprised if microsoft is years sooner in releasing a version
that works well than the linux community, despite that everyone will understand
that bugfixing assembly code is a lot harder than fixing a bit of C code.

Best regards,
Vincent

>
>Bo Persson
>bop2@telia.com



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