[Beowulf] NVIDIA GPUs, CUDA, MD5, and "hobbyists"

Prentice Bisbal prentice at ias.edu
Wed Jun 18 07:51:04 PDT 2008

I seem to have muddied the waters of the original NVIDIA/CUDA post.
Someone made the inaccurate statement that CUDA programming is difficult
and time-consuming. I cited the MD5-example of my colleague as an
example of how easy it is to port the code, and how significant the
performance improvements could be.

Some subscribers to this list questions these results,and the discussion
quicky turned away from NVIDIA/CUDA/GPUs to MD5. I forward the e-mails
to my colleague. Since he doesn't subscribe to this list, I'm replying
based on information he has provided me. He hasn't asked me to reply on
his behalf, I'm doing this on my onw to contribute to the discussion.

My colleague who did this work, Mario Juric, is a member at the
Institute for Advanced Study (member = postdoc) studying Astrophysics.
Contrary to the assertion by Vincent that CUDA/GPUs are only for
hobbyists, Mario is very interested in using GPUs to speed up his
astrophysics research. The biggest hindrance to doing "real" work with
GPUs is the lack of dual-precision capabilities. As we all know, that
hindrance was eliminated yesterday.

In November of 2007, Mario organized the AstroGPU Workshop here at the
Institute to discuss the use of GPUs in Astrophysics
(http://www.astrogpu.org/). This workshop serves as proof that there are
 scientists serious about using GPUs for real work (not just hobbyists).

Now about that MD5 discussion... I forwarded Mario the replies to my
post, and he replied thusly:


Hi Prentice,
    The guy ... is right -- it's throughput for a lot of simultaneous
computations, not for a computation of a single hash. If you attempt to
compute a single hash on an entire card, you won't get any improvement.
Same as you wouldn't if you tried it on a single vs. quad core CPU. But
if you compute four hashes, than single vs. quad makes a huge
difference. And the GPU cards are effectively 128 core CPUs, so when you
need to compute millions of hashes...

Feel free to e-mail them my online writeup at:


The full source code is there as well. That should clear a lot of things


For those of you with questions about the MD5 performance, please see
the link above, and better yet, take a look at Mario's code. The link
includes lots of pretty graphs ;)


Elcomsoft did the same thing, and sells it commercially:



NVIDIA has promised us some new GPUs through their Professor Partner
program. I'm sure once we get our hands on them, we'll do more
coding/benchmarking. Not sure if they'll be DP-capable units.

Prentice Bisbal
Linux Software Support Specialist/System Administrator
School of Natural Sciences
Institute for Advanced Study
Princeton, NJ

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