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Peter Menegay August 12, 2002 14:22

Large Jobs and Memory
 
We do alot of large CFD runs at our site with Star-CD. We are considering upgrading our workstations to dual Xeon 2.4 GHz with 8 GB RAM. The 8 GB is available in server configurations. My question is, even if we have all that memory, will Star-CD be able to access it? OS will be Linux, presumably 32 bit. So far, with dual Xeon 1.7 GHz, I have never been able to access more than 2 GB.

Thanks,

Peter


steve August 13, 2002 09:21

Re: Large Jobs and Memory
 
I have seen prostar grab more than 3Gb on a Linux system with 4Gb of memory. The theoretical max is 4Gb (2^32) on any 32bit system (linux) that ignores the "-" sign or 2Gb (ie 2^31)on other systems that do not ignore it. It can't possibly assign more than 4GB to any one process. If you have 8GB it may be able to assign 4Gb to two processes at the same time (I don't really know).

The memory in STAR is laid out differently than prostar in that prostar gets it all from malloc, while STAR puts it in fixed fortran common blocks. I have seen this have an effect before on linux in particular and how much memory the programs can grab, so I can't be sure that STAR will grab more than 2GB (never really tried) even though prostar can.

mikhail September 4, 2002 07:53

Re: Large Jobs and Memory
 
I have succeeded in run of 4 GB StarCD 3.15 task with Intel850 chipset under RedHat7.1 os. More over, if your have prohpc your will be able access to all memory. (but it won't double run speed).


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