Just as another note, I checked out the AMBER output from running on a
GTX570,
|------------------- GPU DEVICE INFO --------------------
|
| CUDA Capable Devices Detected: 1
| CUDA Device ID in use: 0
| CUDA Device Name: GeForce GTX 570
| CUDA Device Global Mem Size: 1279 MB
| CUDA Device Num Multiprocessors: 15
| CUDA Device Core Freq: 1.46 GHz
|
|--------------------------------------------------------
So in that case the Core Freq reported is indeed the correct one, even
though the GTX570 has two lower clock speeds it runs at depending on load
(810 MHz, and 101 MHz)
I know with the 500 series, the available nVidia tools for linux will least
allow you to set the device to maintain the highest clock speeds regardless
of load. I have NOT done that in the above case, but if such a thing is
possible for the 600 series, it might be worth looking at. Sadly the tool
is only easily usable if you have a display connected although if you
google "Axel Kohlmeyer" and go to his homepage there are some suggestions
on installing these tools on a typical server where you can fake a display.
~Aron
On Sat, Feb 23, 2013 at 2:33 PM, filip fratev <filipfratev.yahoo.com> wrote:
> Hi Ross, Aron and all,
> Thanks for your detail answers!!
>
> So, it seems that nobody know whether Nvidia
> support the boost speed even on GTX680. Moreover, because the core speed is
> wrongly (I hope) printed as in the case of Amber 12 as well in all
> benchmark
> applications, we can see the difference only if compare the GTX680 to K10
> (1
> GPU) where we can see 37% performance increase (JAC), which can comes only
> from the
> core/memory clock.
>
> Ross, please ask Nvidia about these issues.
> I've already asked them but don't believe that will receive any adequate
> answer.
> I also asked several users but nobody knows and they told me that Nvidia
> never
> said something about their Boost technology under Linux.
> Thus, at this point I think that we can trust
> only to your information.
>
> Regards,
> Filip
>
>
> ________________________________
> From: Ross Walker <ross.rosswalker.co.uk>
> To: filip fratev <filipfratev.yahoo.com>; AMBER Mailing List <
> amber.ambermd.org>
> Sent: Saturday, February 23, 2013 6:45 AM
> Subject: Re: [AMBER] GTX Titan was finally released
>
> Hi Filip,
>
>
> >As you know I plan to purchase few GTX Titans:)
> >but I am not sure actually at what speed they will run: 836, 876 or 993
> >Mhz?
> >It seems that by default (80C target) the Titan
> >runs under Windows only on the maximal core speed (around 1Ghz) not the
> >boost
> >one. It goes back to 836 only if the temperature rises above 80C but with
> >100%
> >fan speed this looks almost impossible. At least this is what I saw from
> >the
> >reviews.
>
> No idea since I am still waiting for NVIDIA to actually send me a
> development card to try this with. I guess the Titan's will be vaporware
> for a while. I am intrigued to know about how the clock speed will work
> and I am waiting for NVIDIA engineering to get back to me with a
> definitive answer. Note the Titan can also be run in two modes from what I
> gather. One with the DP cores turned down and the SP cores clocked up
> (Gaming mode) and one where it turns on all the DP cores and clocks down
> the single precision (CUDA mode). Note AMBER was retooled for the GK104
> chip to not use double precision anymore. It uses a combination of single
> and fixed precision which we worked very hard to tune to match/better the
> SPDP accuracy. Thus it is entirely possible that one will actually want to
> run the Titan cards in gaming mode when running AMBER. Of course this is
> entirely speculation until I lay my hands on one. The thermal window also
> has potential issues for 4 GPU boxes but there may end up being a hack to
> disable the down clocking and allow temps over 80C. Note most cards I have
> (GTX680s) run around 90C right now. SDSC runs it's machine room at 85F in
> order to save power - since disks and CPUs don't care if the room is 85F
> vs 60F. This might be a different story if the GPUs throttle based on
> temperature but I guess we'll just have to wait and see.
>
> >
> >I was also horrified to see that many GTX680
> >(and other cards) users complain that under Linux their cards run at only
> >about
> >700Mhz core speed instead of 1Ghz. What is your experience with GTX 680?
> >I was also wondering whether the GTX680 use the
> >boost clock during the Amber calculations or the just the base one?
> >
>
> I think this is just speculation. When you run AMBER with a GTX680 it
> prints the following:
>
>
> |------------------- GPU DEVICE INFO --------------------
> |
> | CUDA Capable Devices Detected: 1
> | CUDA Device ID in use: 0
> | CUDA Device Name: GeForce GTX 680
> | CUDA Device Global Mem Size: 2047 MB
> | CUDA Device Num Multiprocessors: 8
> | CUDA Device Core Freq: 0.71 GHz
> |
> |--------------------------------------------------------
>
>
>
> But this is a query that occurs at the very beginning of a run before any
> CUDA kernels have been run. I believe that when unloaded the 680 in Linux
> clocks down to 705MHz to save power. When you stress it hard it
> automatically clocks up the frequency. I am not sure if there is way to
> check this though while the card is under load. Certainly the performance
> we see would be what it is if the clock speed was only 705MHz. I am asking
> NVIDIA engineering to clarify though.
>
> >Finally, what is the performance difference of
> >pmemdCuda under Linux and Cygwin?
>
> Never tried and I very much doubt you'll be able to get pmemd.cuda
> compiled under cygwin. Cygwin emulates things through the cygwin dll and
> so you'd need a cygwin compatible version of the nvidia compiler I'd
> expect.
>
> Note have a native Windows version of pmemd.cuda but never released the
> binary since the performance is about half that of what it is on Linux due
> to a bug in cuda 4.2 under windows that limited performance. cuda 3 showed
> good performance under windows but you can't use that with AMBER 12. We
> haven't had time to get back to looking at this with cuda 5 unfortunately.
>
> All the best
> Ross
>
> /\
> \/
> |\oss Walker
>
> ---------------------------------------------------------
> | Assistant Research Professor |
> | San Diego Supercomputer Center |
> | Adjunct Assistant Professor |
> | Dept. of Chemistry and Biochemistry |
> | University of California San Diego |
> | NVIDIA Fellow |
> | http://www.rosswalker.co.uk | http://www.wmd-lab.org |
> | Tel: +1 858 822 0854 | EMail:- ross.rosswalker.co.uk |
> ---------------------------------------------------------
>
> Note: Electronic Mail is not secure, has no guarantee of delivery, may not
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>
>
>
>
>
>
>
>
>
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--
Aron Broom M.Sc
PhD Student
Department of Chemistry
University of Waterloo
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Received on Sat Feb 23 2013 - 12:30:03 PST
