| 9:23:50 AM PDT - Thu, May 24th 2012 |
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The default memory settings for NWChem are pretty small, 400mb I think (unless it was changed at compile time). So, simply without the memory keyword the calculation does not have enough memory to proceed.
Note, you may want to check how much memory the OS is taking. Fully loading the memory with NWChem will create problems. Swapping memory is not going to work well or at all.
Let's take the 48 core 1800mb case. This means that each processor is going to allocate 450 mb of local heap, 450 mb of local stack (these two are not the problem), and 900 mb of global shared memory. Now, on a single node this is allocated in shared memory segments. 900 mb * 48 cores means the code with try to potentially allocate a single (over) 43 GByte segment of memory.
Let me try and run the input. I'll try 16 cores with 3500 mb.
Bert
[QUOTE=KarlB May 24th 4:00 pm]Hello all,
I’m working with DBauer on the calculation he mentioned previously in this thread. We’ve also been working on a much larger cluster computer that has 96 gigs of ram per node in an effort to complete this calculation.
Yesterday I did a run with 16 cores with the full 96 gigs of ram split between them (6 gigs per core). In nwchem I used the directive “memory total 6144 mb” to assign the memory to be used. This calculation failed at the same point all the previous have with the error: Error Run 1
I then ran the same calculation in the same manner this time removing the memory directive and allowing nwchem to assign the memory itself. This calculation also failed with the error: Error Run 2
The cluster that I was running on has a monitoring system that allows for reviewing of node performance. I went and reviewed the system performance and found that in both calculations NWChem never used more than ~4 gigs of ram for these calculations which I find puzzling. The 4 gig threshold makes me suspicious of a 32 bit limit somewhere.
Link to Images: Images
Link to Input 1: Input run 1
Link to Input 2: Input run 2
Outputs can be provided if more clarification is needed.
Notes:
1st calculation ran from ~1pm-8pm
2nd calculation ran from ~10:30pm-5:30am
The calculation running before till ~1pm was a Raman calculation I did with 48 cores and “memory 1800 mb”
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