- Forwarded message from Prentice Bisbal prent...@ias.edu -
From: Prentice Bisbal prent...@ias.edu
Date: Thu, 22 Dec 2011 11:53:39 -0500
To: Beowulf Mailing List beow...@beowulf.org
Subject: Re: [Beowulf] 3.79 TFlops sp, 0.95 TFlops dp, 264 TByte/s, 3 GByte,
198 W @ 500 EUR
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Just for the record - I'm only the messenger. I noticed a
not-insignificant number of booths touting FPGAs at SC11 this year, so I
reported on it. I also mentioned other forms of accelerators, like GPUs
and Intel's MIC architecture.
The Anton computer architecture isn't just a FPGA - it also has
custom-designed processors (ASICS). The ASICs handle the parts of the
molecular dynamics (MD) algorithms that are well-understood, and
unlikely to change, and the FPGAs handle the parts of the algorithms
that may change or might have room for further optimization.
As far as I know, only 8 or 9 Antons have been built. One is at the
Pittsburgh Supercomputing Center (PSC), the rest are for internal use at
DE Shaw. A single Anton consists of 512 cores, and takes up 6 or 8
racks. Despite it's small size, it's orders of magnitude faster at
doing MD calculations than even super computers like Jaguar and
Roadrunner with hundreds of thousands of processors. So overall, Anton
is several orders of magnitudes faster than an general-purpose processor
based supercomputer. And sI'm sure it uses a LOT less power. I don't
think the Anton's are clustered together, so I'm pretty sure the
published performance on MD simulations is for a single Anton with 512
cores
Keep in mind that Anton was designed to do only 1 thing: MD, so it
probably can't even run LinPack, and if it did, I'm sure it's score
would be awful. Also, the designers cut corners where they knew the
safely could, like using fixed-precision (or is it fixed-point?) math,
so the hardware design is only half the story in this example.
Prentice
On 12/22/2011 11:27 AM, Lux, Jim (337C) wrote:
The problem with FPGAs (and I use a fair number of them) is that you're
never going to get the same picojoules/bit transition kind of power
consumption that you do with a purpose designed processor. The extra
logic needed to get it reconfigurable, and the physical junction sizes
as well, make it so.
What you will find is that on certain kinds of problems, you can implement
a more efficient algorithm in FPGA than you can in a conventional
processor or GPU. So, for that class of problem, the FPGA is a winner
(things lending themselves to fixed point systolic array type processes
are a good candidate).
Bear in mind also that while an FPGA may have, say, 10-million gate
equivalent, any given practical design is going to use a small fraction of
those gates. Fortunately, most of those unused gates aren't toggling, so
they don't consume clock related power, but they do consume leakage
current, so the whole clock rate vs core voltage trade winds up a bit
different for FPGAs.
The biggest problem with FPGAs is that they are difficult to write high
performance software for. With FORTRAN on conventional and vectorized and
pipelined processors, we've got 50 years of compiler writing expertise,
and real high performance libraries. And, literally millions of people
who know how to code in FORTRAN or C or something, so if you're looking
for the highest performance coders, even at the 4 sigma level, you've got
a fair number to choose from. For numerical computation in FPGAs, not so
many. I'd guess that a large fraction of FPGA developers are doing one of
two things: 1) digital signal processing, flow through kinds of stuff
(error correcting codes, compression/decompression, crypto; 2) bus
interface and data handling (PCI bus, disk drive controls, etc.).
Interestingly, even with the relative scarcity of FPGA developers versus
conventional CPU software, the average salaries aren't that far apart.
The distribution on generic coders is wider (particularly on the low
end.. Barriers to entry are lower for C,Java,whathaveyou code monkeys),
but there are very, very few people making more than, say, 150-200k/yr
doing either. (except in a few anomalous industries, where compensation
is higher than normal in general). (also leaving out equity
participation type deals)
On 12/22/11 7:42 AM, Prentice Bisbal prent...@ias.edu wrote:
On 12/22/2011 09:57 AM, Eugen Leitl wrote:
On Thu, Dec 22, 2011 at 09:43:55AM -0500, Prentice Bisbal wrote:
Or if your German is rusty:
http://www.zdnet.com/blog/computers/amd-radeon-hd-7970-graphics-card-lau
nched-benchmarked-fastest-single-gpu-board-available/7204
Wonder what kind of response will be forthcoming from nVidia,
given developments like
http://www.theregister.co.uk/2011/11/14/arm_gpu_nvidia_supercomputer/
It does seem that x86 is dead, despite good Bulldozer performance
in