Memory allocation in Molpro

H. -J. Werner werner at
Tue Jul 30 16:45:47 BST 2002

Dear Molpro users,
sometimes the question came up why not more memory than something like
90-110 MW could be allocated with Molpro on Linux boxes. 
This problem can be avoided as follows:

set in CONFIG
GMALLOC="0" rather than "1"

then do 

rm src/util/gmalloc.o
ar -d lib/libmolpro.a gmalloc.o 

Then the problem should disappear, provided you have a recent linux kernel.
The replacement for gmalloc was better with older operating systems (up to
kernel 2.4.9) but for later ones the system gmalloc seems to be much better. 
Also, we found that problems with hanging operating systems seen with kernels
later than 2.4.9 were caused by the iMolpro gmalloc replacement.

In summary my recommendation is:

1.) Use a recent linux kernel, e.g., 2.4.18
2.) Remove the Molpro gmalloc.o, and use the system one.

Then you should be able to use the whole memory of your machine.

We will provide a patch for this in the near future.

Best regards
Joachim Werner

Prof. Hans-Joachim Werner
Institute for Theoretical Chemistry
University of Stuttgart
Pfaffenwaldring 55
D-70569 Stuttgart, Germany
Tel.: (0049) 711 / 685 4400
Fax.: (0049) 711 / 685 4442
e-mail: werner at

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