[Beowulf] More AMD rumors

Robert G. Brown rgb at phy.duke.edu
Mon Nov 19 09:12:57 PST 2012


On Mon, 19 Nov 2012, Vincent Diepeveen wrote:

> If you measure memory latency at all 8 cores at the same time, it's
> even more horrible.

Thanks for a remarkably clear and useful reply, Vincent.  This nearly
precisely mirrors my own measurements with a more floating point
intensive task.  The larger i7-3770 cache and its 8 operational contexts
(it is a four core system but it maintains two completely independent
contexts per core, IIRC) seem to give it an overwhelming advantage over
the FX with its eight "real" cores but much smaller cache.  Interesting
to see that this continues with the (I assume) integer/logic intensive
chess code.

Basically, the i7 looks like a butt-kicking good processor, with the one
problem being that it doesn't look like a multiprocessing cpu (at least
I can't find a dual i7 motherboard, although in principle it appears to
be possible, leaving one with Xeons that don't LOOK like they would
perform as well although I'd be interested in information on that as
well.

At the moment, single processor i7's look like they might actually be
the world's fastest, at least on a per core basis.  OTOH, it might well
be that putting two of them on a single board would horribly saturate
the memory bus and cause memory management collisions and worse and cost
them their advantage.

I'm getting ready to do some very data intensive stuff -- terabyte-scale
datasets being chewed to pieces basically -- to the point where my
"cluster" will probably be a pile of RAIDs each with its own private
copy of the datasets in questions and equipped with an i7 motherboard,
which seems odd somehow (as the i7 motherboards aren't generally
configured as "server" motherboards) but the Xeons all run at lower
clock and are older technology.

Comments from anyone else?

    rgb

>
>> I would have hoped that AMD would dig in an innovate and
>> regain at least parity if not the lead, because it is good for the
>> industry for Intel to have serious competition, but while Intel could
>> make money and survive as second best to AMD, AMD can't make any money
>> as second best to Intel...
>
> We must split of course the 2 worlds of HPC performance.
> In fact htere is 3 but let's do a rough 2 world division
>
> a) floating point or vectorized performance (can be integers as well)
>
> We skip A : the manycores have won there.
>
> b) integer performance non-vectorized
>
> For integers and branches if i take a huge program like Diep.
>
> http://www.lostcircuits.com/mambo//index.php?
> option=com_content&task=view&id=105&Itemid=42&limit=1&limitstart=13
>
> More is better.
>
> i7-3960X-EE : 2.0 Million chess positions a second   (12 logical cores)
> i7-980x turbo: 1.85 Million chess positions a second (12 logical cores)
> i7-3770k:         1.47 million chess positions a second (8 logical
> cores)
> AMD Phenom X6 1100T : 1.34 million chess positions a second (6 cores)
> AMD Phenom X6 1090T : 1.30 million chess positions a second (6 cores)
> FX-8150 : 1.22 million chesspositions a second (8 mini cores)
>
> The FX-8150 is AMD's latest 'bulldozer' CPU.
>
> The problem is the new generation FX-8150 at a NEW process
> technology, with 2 billion transistors or so (caches counted
> - the initial press release from AMD - not the later one where they
> creatively not counting things reached 1.2 billion)  is not beating
> their own old design.
>
> Furthermore another big problem is power usage.
>
> http://www.lostcircuits.com/mambo//index.php?
> option=com_content&task=view&id=105&Itemid=42&limit=1&limitstart=6
>
> Under full load:
>
> Phenom X6 1090T : 69.6 watt,
> Phenom X6 1100T : 92 watt
>
> We see how the 1100T already was clocked a tad too high by AMD, which
> explains the huge power increase.
>
> Now the FX-8150 : 115.2 watt
>
> As if Law of Moore garantueeing progress doesn't exist...
>
> As for you, in many benchmarks you did do maybe multiplication was
> important. Each minicore has its own multiplication unit.
> Sounds good huh?
>
> So far the good news: the problem is: it's also over 2 times slower
> that unit...
>
> Please note that bulldozer does have AVX. From benchmarks we know
> that both intel as well as AMD with this bulldozer,
> had tried to optimize performance for game. Games using AVX especially.
>
> It's not doing bad there in fact. Worse than the quadcore intels. I
> don't want a quadcore chip though.
> I want a million cores.
>
>>
>>     rgb
>>
>>>
>>> --
>>> Doug
>>>
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>>
>> Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
>> Duke University Dept. of Physics, Box 90305
>> Durham, N.C. 27708-0305
>> Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu
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Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu




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