ram limit.
- Torsten
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18 years 2 months ago #1120
by Torsten
ram limit. was created by Torsten
Hello,
why is there a ram limit of 2048mb? is there any way to use mor ram? even with the gcpc-solver, i can \"only\" resolve problems up to 1,2mio dof.
regards,
thorsten
why is there a ram limit of 2048mb? is there any way to use mor ram? even with the gcpc-solver, i can \"only\" resolve problems up to 1,2mio dof.
regards,
thorsten
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18 years 2 months ago #1121
by Joël Cugnoni
Joël Cugnoni - a.k.a admin
www.caelinux.com
Replied by Joël Cugnoni on topic Re:ram limit.
Hello,
the Ram limit is due to x86 32bit architecture & Fortran limitation to 2048mb on this architecture.
With a 32bit OS, the address space of a program can only span up to 2048mb; so only options to circumvent this are in general:
1) use distributed architecture and split the problems in subproblems => cluster & MPI
2) move to a 64bit CPU & OS & recompile everything for this new architecture.
For Code-Aster: the only option is 2) at the present time (an MPI / cluster implementation is being developped, but still experimental). But to recompile aster on a 64bit OS (Suse for example), you will need a commercial compiler like Intel C/ Forran compilers & some good background in compilation of libraries etc..
From my experience with Aster, you can try to optimize the usage of the memory by:
1) playing with the parameters of the \"DEBUT\" command
2) the GCPC solver in Aster is not the most efficient solver in terms of memory because it uses a single matrix storage that needs to be all in memory to run
3) the best solver is Multi-Front because it splits the matrices in several parts, all parts are be stored on the disk except the one that is being processed.
the Ram limit is due to x86 32bit architecture & Fortran limitation to 2048mb on this architecture.
With a 32bit OS, the address space of a program can only span up to 2048mb; so only options to circumvent this are in general:
1) use distributed architecture and split the problems in subproblems => cluster & MPI
2) move to a 64bit CPU & OS & recompile everything for this new architecture.
For Code-Aster: the only option is 2) at the present time (an MPI / cluster implementation is being developped, but still experimental). But to recompile aster on a 64bit OS (Suse for example), you will need a commercial compiler like Intel C/ Forran compilers & some good background in compilation of libraries etc..
From my experience with Aster, you can try to optimize the usage of the memory by:
1) playing with the parameters of the \"DEBUT\" command
2) the GCPC solver in Aster is not the most efficient solver in terms of memory because it uses a single matrix storage that needs to be all in memory to run
3) the best solver is Multi-Front because it splits the matrices in several parts, all parts are be stored on the disk except the one that is being processed.
Joël Cugnoni - a.k.a admin
www.caelinux.com
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18 years 2 months ago #1125
by Torsten
Replied by Torsten on topic Re:ram limit.
admin wrote:
thanks for reply. i have a 64bit linux. unfortunaly, i have no background in doing such things.
but what would be price of such commercial compilers?
to recompile aster on a 64bit OS (Suse for example), you will need a commercial compiler like Intel C/ Forran compilers & some good background in compilation of libraries etc..
thanks for reply. i have a 64bit linux. unfortunaly, i have no background in doing such things.
but what would be price of such commercial compilers?
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18 years 2 months ago #1126
by Torsten
Replied by Torsten on topic Re:ram limit.
what abaout the windows-version and the 3gb switch, or running the 32bit-win on a xp x64? would this work?
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18 years 2 months ago #1129
by Joël Cugnoni
Joël Cugnoni - a.k.a admin
www.caelinux.com
Replied by Joël Cugnoni on topic Re:ram limit.
Hi,
there might be a Free-for-Personal use version of Intel compilers for Linux, but I don't know if it is available in 64bit version in this licence... see Intel web site / Compiler section to have a better idea.
If this is not the case, a professionnal compiler for C & Fortran is around (or above) 1'000 euros !!
I heard that some have tried to use gfortran, but I don't know if they succeeded... there might be some answers on Code-Aster forums: www.code-aster.com/forum/index.php
Regards,
J.Cugnoni
PS: Windows version developped by NECS is even limited to 1Gb... for unknown reasons.
Anyway, in 32bit application, even in Windows XP with /3gb or in Windows 64bit, the max amount of RAM for ONE application is 2Gb. The difference is that you can run several apps + system more comfortably!! The only REAL solution is compiling a 64bit application... sorry to say!!
there might be a Free-for-Personal use version of Intel compilers for Linux, but I don't know if it is available in 64bit version in this licence... see Intel web site / Compiler section to have a better idea.
If this is not the case, a professionnal compiler for C & Fortran is around (or above) 1'000 euros !!
I heard that some have tried to use gfortran, but I don't know if they succeeded... there might be some answers on Code-Aster forums: www.code-aster.com/forum/index.php
Regards,
J.Cugnoni
PS: Windows version developped by NECS is even limited to 1Gb... for unknown reasons.
Anyway, in 32bit application, even in Windows XP with /3gb or in Windows 64bit, the max amount of RAM for ONE application is 2Gb. The difference is that you can run several apps + system more comfortably!! The only REAL solution is compiling a 64bit application... sorry to say!!
Joël Cugnoni - a.k.a admin
www.caelinux.com
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