Re: [AMBER-Developers] PMEMD now built by default

From: Gustavo Seabra <gustavo.seabra.gmail.com>
Date: Tue, 2 Mar 2010 21:52:08 -0300

Building PMEMD breaks in cygwin:

$ ./configure -cygwin gnu
[...]
OK

$ make -f Makefile_at
[...]
Compilation of AT ends OK

$ make serial
[...]
cpp -traditional -P -DBINTRAJ -DDIRFRC_EFS -DDIRFRC_COMTRANS
-DDIRFRC_NOVEC -DFFTLOADBAL_2PROC -DPUBFFT bintraj.fpp bintraj.f90
gfortran -O3 -mtune=generic -msse -mfpmath=sse -c bintraj.f90
bintraj.f90:73.12:

  use netcdf
            1
Fatal Error: Can't open module file 'netcdf.mod' for reading at (1):
No such file or directory
make[2]: *** [bintraj.o] Error 1
make[2]: Leaving directory
`/cygdrive/c/Users/seabra/Cygwin-home/local/amber11/src/pmemd/src'
make[1]: *** [install] Error 2
make[1]: Leaving directory
`/cygdrive/c/Users/seabra/Cygwin-home/local/amber11/src/pmemd'
make: *** [serial] Error 2

Gustavo Seabra
Professor Adjunto
Departamento de Química Fundamental
Universidade Federal de Pernambuco
Fone: +55-81-2126-7450 Ext. 5021



On Tue, Mar 2, 2010 at 7:41 PM, Robert Duke <rduke.email.unc.edu> wrote:
> Oops - said it wrong. I have some pre-em64_t chips where vectorizing the
> direct force routines (here actually meaning local array caching so code
> vectorization will be more likely) is helpful; ie., using DIRFRC_NOVEC
> hurts...
> - Bob
> ----- Original Message ----- From: "Robert Duke" <rduke.email.unc.edu>
> To: "AMBER Developers Mailing List" <amber-developers.ambermd.org>
> Sent: Tuesday, March 02, 2010 5:35 PM
> Subject: Re: [AMBER-Developers] PMEMD now built by default
>
>
>> Hi Ross,
>> I think there are two main factors that influenced optimization, just off
>> the top of my head: 1) RISC vs. CISC, and 2) amount of cache. Vectorization
>> is these days more of a CISC feature, I would think.  At any rate, it is
>> probably harder to predict whether DIRFRC_NOVEC helps or hurts due to the
>> interplay of several factors (so there actually are pre-em64_t chips where
>> it clearly helps).  I should try to get my hands on a nehalem to run my
>> tuning suite, and see what is really optimal these days.  FFTW helps about
>> 10% on a single processor, but the benefit is quickly lost in the noise past
>> 2-4 processors.  I generally don't bother with it because it is a pain to do
>> the compile/link (actually how I feel about netcdf and mkl (especially)
>> these days).  FFTLOADBAL_2PROC is a once-in-a-while useful optimization, but
>> not critical; it allows assignment of all fft work to one of two processors,
>> followed by redistribution as necessary. It is one of those things where it
>> is hard to predict the benefit due to interplay between interconnect speed
>> vs. caching effects in the fft code. I may be incorrect in assuming this,
>> but I do assume most folks run on more than 2 processors these days, so it
>> is not a big deal whether we make it a default or not.
>> Regards - Bob
>> ----- Original Message ----- From: "Ross Walker" <ross.rosswalker.co.uk>
>> To: "'AMBER Developers Mailing List'" <amber-developers.ambermd.org>
>> Sent: Tuesday, March 02, 2010 5:02 PM
>> Subject: RE: [AMBER-Developers] PMEMD now built by default
>>
>>
>>> Hi Bob,
>>>
>>>> A few quick notes -
>>>> The DIRFRC_* defines are important; you need to at least default to
>>>> what is
>>>> being used for em64t on these.  A good example is DIRFRC_EFS which
>>>> enables
>>>> direct force calc splining optimizations that give you single processor
>>>> speedups in the range of 30%. The other stuff is in the 5-10% range
>>>> typically, and if you get the em64t defaults, you probably won't be far
>>>> off
>>>> target.
>>>
>>> Indeed. Right now when you issue ./configure intel
>>>
>>> You get:
>>>
>>> PMEMD_FPP=cpp -traditional  -P  -DBINTRAJ -DDIRFRC_EFS -DDIRFRC_COMTRANS
>>> -DDIRFRC_NOVEC -DFFTLOADBAL_2PROC -DPUBFFT
>>> PMEMD_F90=ifort
>>> PMEMD_FOPTFLAGS=-fast
>>>
>>> Which uses the correct ifdefs I think. I know there are things like FFTW
>>> but
>>> I never saw much speedup with that so figured it wasn't worth the hassle.
>>> The one that seems strange is the FFTLOADBAL_2PROC. This only does
>>> anything
>>> if you are running mpirun -np 2. Yes? Is there any harm in having this
>>> there
>>> or should we consider stripping it out?
>>>
>>> I assume the vec version of DIRFRC_ is mainly aimed at RISC systems
>>> correct?
>>> Have you tried it of late on any EM64T systems, the ones with SSE5 etc?
>>> The
>>> -fast does vectorization and full interprocedural optimization at linking
>>> stage so the difference may not be so great now but was wondering if you
>>> had
>>> tried it with Nehalm systems?
>>>
>>>>  But you do need to pick up this level of optimization that is
>>>> basically implemented through alternative code paths.  The slow mpi
>>>> stuff is
>>>> pretty unimportant now, and more likely to cause problems because folks
>>>> include it for non-ethernet systems, so seeing that go away is good
>>>> (there
>>>> is a potential for small systems to run out of mpi buffer space
>>>> however,
>>>> which can cause fairly annoying system hangs; something to watch out
>>>> for).
>>>
>>> Yeah, I saw that a lot because people (including me) would use mpich for
>>> running just on our desktops. When these were dual core it made no
>>> difference but now with 8 or 12 or even 16 cores in a desktop it starts
>>> to
>>> hurt.
>>>
>>>> It is true that a lot of the alternative codepath complexity has to do
>>>> with
>>>> supporting various risc architectures and itanium, both of which have
>>>> lost
>>>> the wars.  On netcdf, well, in reality, at least in my experience, I
>>>
>>> Yeah a real shame but cheapness is everything these days... :-( In the
>>> minds
>>> of the politicians they are extending the American ideal to
>>> supercomputers
>>> as well so it is stated that '...all flops are created equal'.
>>>
>>>> install would typically take.  Gosh, I hope ibm power systems become
>>>> available again somewhere; they are the best machines available in my
>>>> opinion; I guess they are expensive too though.
>>>
>>> Yeah there are a couple of bright sparks with power 7 systems coming
>>> online
>>> but getting access to them will be hard and I doubt anyone can convince a
>>> university to buy one in place of cheap flop rich cluster these days. :-(
>>>
>>> All the best
>>> Ross
>>>
>>> /\
>>> \/
>>> |\oss Walker
>>>
>>> | Assistant Research Professor |
>>> | San Diego Supercomputer Center |
>>> | Tel: +1 858 822 0854 | EMail:- ross.rosswalker.co.uk |
>>> | http://www.rosswalker.co.uk | http://www.wmd-lab.org/ |
>>>
>>> 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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>>>
>>>
>>
>>
>>
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Received on Tue Mar 02 2010 - 17:00:03 PST
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