There is no I/O in the CUDA code whatsoever. All control of overall
program flow and execution is done through the existing FORTRAN
infrastructure. The CUDA code merely hotwires the calculation and
tricks the FORTRAN into thinking it's doing it itself through a
variety of jiggery pokery. That's my story and I'm sticking to it.
Scott
On Wed, May 25, 2011 at 10:27 AM, Jason Swails <jason.swails.gmail.com> wrote:
> Just to chime in here -- NetCDF is hooked into pmemd and pmemd.cuda through
> the netcdf fortran module, NOT through statically/dynamically linked
> libraries. The netcdf.mod file is taken from the AmberTools NetCDF
> installation, so libnetcdf.a and libnetcdff.a shouldn't be necessary in the
> config.h
>
> Furthermore, I don't think any file writing is done through the CUDA code
> (just through the Fortran code), so you shouldn't need to add any NetCDF
> libraries to any CUDA variables. Also, libraries only ever need to be
> included on the link line, so I'm not sure what changes you claim to have
> had to make and how they could have possibly been necessary to build
> pmemd.cuda...
>
> I've tested it on AmberTools 1.5 + Amber11, and it works fine for me without
> having to massage the config.h file any more than AT15_Amber11.py does
> already.
>
> All the best,
> Jason
>
> On Wed, May 25, 2011 at 12:38 PM, Ross Walker <ross.rosswalker.co.uk> wrote:
>
>> Hi Paul,
>>
>> > Attached are the test logs running the test suite on a CentOS 5.6
>> > machine
>> > with a Tesla C2070.
>>
>> The gb_ala3 case is, I believe, just an issue with the random number stream
>> being different. This can happen a lot with ntt=3 since the use of random
>> numbers changes depending on the hardware configuration. Working around
>> this, for test purposes, hurts performance a lot. This failure (and
>> dhfr_ntb2_ntt3). The rest look to just be rounding differences so I think
>> you are good. I am not sure why there are so many differences though since
>> the test case saved outputs should be based on C2070's. Thus given the
>> modifications you made below I would be a little wary.
>>
>> > There was a bit of massaging to compile the cuda config. In fact, I had
>> > to
>> > modify PMEMD_CU_FLAGS to include the arlibs of libnetcdf.a and
>> > libnetcdff.a
>> > along with the full path to the installation path of the shared
>> > libraries.
>>
>> I am little confused why you needed to make these changes. Unless something
>> in AMBER Tools 1.5 has messed up the GPU compilation. AMBER should compile
>> it's own netcdf so you should not need to make any changes here. Did you
>> also apply all the bugfixes? - I guess I should find (invent) time to try
>> building AMBER 11 + patches + AmberTools 1.5 myself. - What NVIDIA cuda
>> compiler version are you using?
>>
>> The development tree off of what AMBERTools 1.5 was based works fine for me
>> and there will be a big GPU update shortly so I never bothered to test with
>> AMBERTools 1.5 so it is possible someone messed something up with the netcdf
>> libraries etc but I am still surprised you had to modify things to get it to
>> build.
>>
>> Does the rest of AMBER (AmberTools and AMBER CPU etc build fine in serial
>> or parallel?) - You should really make sure all the CPU compilation and
>> tests run fine before trying to build the GPU version.
>>
>> 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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>>
>
>
>
> --
> Jason M. Swails
> Quantum Theory Project,
> University of Florida
> Ph.D. Candidate
> 352-392-4032
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Received on Wed May 25 2011 - 11:00:03 PDT
