PC GAMESS/Firefly-related discussion club

Learn how to ask questions correctly

Alex Granovsky
gran@classic.chem.msu.su

1. The memory allocated using MWORDS/MEMORY keywords is allocated
on a per process instance basis. You are trying to allocate
approximately 4*3GB = 12 GB RAM but only have 8 GB of RAM available.
This causes excessive paging and seriously degrades performance,
as well as the lifetime of our HDDs.

Try to run your job requesting only e.g. 260 MWORDS or perhaps
even smaller amount.

Actually, there are already multiple threads on this forum discussing
optimal memory allocation strategies running in parallel on SMP/multi-core systems.

2. Note that the following p2p settings are only relevant for MP2 at present:

 $P2P xdlb=.t. mxbuf=2048 $END

Moreover, mxbuf=2048 (p2p buffer size in kilobytes) is only
recommended for shared memory version of p2p interface, which is
available only for Windows and OS X at present. Otherwise, the
default, much smaller size is optimal. Actually, you are setting p2p
buffer to be 2 MB per each process; however, it is allocated
(and thus consumes some extra memory) but is never used.

Regards,
Alex









On Wed May 20 '09 10:04am, Veinardi Suendo wrote
------------------------------------------------
>Dear Prof. Alex and Firefly users,

>Recently, we are working on CI calculation to obtain UV absorption spectra of porphyrin related molecules using Firefly. However, we faced some problems when we deal with a slightly higher basis set or using TDDFT calculation. The calculation seems to work properly, but I found that the memory becomes an important issue. Here, we observed that the processors were idle in a quite long period while the program took almost all memory. In this calculation, we carried out on a single PC with Intel Core2 Quad Processor Q9400, CentOS 5.3 64 bit with RAM of 8GB. In the beginning everything was fine, the program use all cores up to 100 % (4x100%), however, when they start the CI calculation, I do not know why, it seems they really need a lot of memory so they took all 8GB of RAM + 8 GB of swap memory. Is there any option to divide the jobs efficiently, so there will not much processors idle? Below, I list as well the header of our input file:

> $CONTRL SCFTYP=RHF CITYP=TDDFT INTTYP=HONDO
>  EXETYP=RUN MAXIT=100 MULT=1 LOCAL=NONE ICUT=11
>  DFTTYP=B3LYP ITOL=30 D5=1 ICHARG=0 $END
> $SYSTEM TIMLIM=31536000 MEMORY=400000000 KDIAG=0 FASTF=.TRUE. $END
> $P2P p2p=.t. dlb=.t. xdlb=.t. mxbuf=2048 $END
> $SMP Call64=.t. $END
> $BASIS GBASIS=N31 NGAUSS=6 NDFUNC=1 NPFUNC=1 $END
> $D5 D5=.TRUE. F7=.TRUE. G9=.TRUE. $END
> $GUESS GUESS=MOREAD NORB=302 KDIAG=0 PRTMO=.TRUE. $END
> $INTGRL SCHWRZ=.TRUE. NOPK=1 PACKAO=.TRUE. $END
> $TDDFT NSTATE=60 ISTATE=1 TDA=.FALSE. $END
> $SCF DIRSCF=.TRUE. FDIFF=.FALSE. NCONV=6
>  EXTRAP=.TRUE. DAMP=.TRUE. SHIFT=.TRUE. RSTRCT=.TRUE.
>  DIIS=.TRUE. SOSCF=.FALSE. $END
> $STATPT OPTTOL=0.0001 NSTEP=400 Method=GDIIS HESS=GUESS $END
> $DATA

>I am looking forward to hear from you.

>Best regards,

>Veinardi