Hi Filip,
I think you are worrying too much hear. Firstly you are referring to the
double precision clock rate and not the single precision clock. AMBER
stopped relying on the double precision side of things and switched to
fixed point accumulation with the release of the GTX680 and K10. Second
the stock single precision clock will be faster than the K20X so you can
expect performance to be better than the K20X. It also has more cores
active 'I think', don't have the specs here or internet access to check
right now.
Thirdly, the boost clock. AMBER pretty much runs the entire GPU flat out
ALL the time. The boost clock is only useful, as with CPUs, when you are
only using a fraction of the cores. In the case of GPUs unless you are
running very small atom counts this is unlikely to happen so even if the
boost clock was supported it wouldn't do you any good.
In short, I wouldn't worry about it. Let's just wait and see how it truly
performs when the "vaporware" actually turns up.
All the best
Ross
On 2/25/13 2:39 PM, "filip fratev" <filipfratev.yahoo.com> wrote:
>Hi all,
>I received some tests performed. Here is the comparison between LuxMax
>results obtained by GTX660 under Linux and Windows, respectively:
>
>http://img22.imageshack.us/img22/1279/luxmarkubuntu1204.png
>http://img692.imageshack.us/img692/9647/luxmarkwin7.png
>
>According to these results the GTX660 works at 1071Mhz, thus the Boost
>speed and the results between Linux and Windows are similar.
>
>However, Nvidia answered me that the GTX Titan core speed under Linux
>will be 837MHz and about the boost technology this: "unfortunately no,
>boost 1.0/2.0 are only supported on windows."
>Personally I trust on the above tests:)
>If they really caped their GTX GPU's under Linux to the base clock
>presumably only the BIOS hack option will be possible, which is....:)
>
>Regards,
>Filip
>
>
>
>
>________________________________
> From: Aron Broom <broomsday.gmail.com>
>To: filip fratev <filipfratev.yahoo.com>; AMBER Mailing List
><amber.ambermd.org>
>Sent: Saturday, February 23, 2013 10:12 PM
>Subject: Re: [AMBER] GTX Titan was finally released
>
>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
>> be read every day, and should not be used for urgent or sensitive
>>issues.
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>>
>
>
>
>--
>Aron Broom M.Sc
>PhD Student
>Department of Chemistry
>University of Waterloo
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Received on Tue Feb 26 2013 - 08:30:03 PST
