[GE users] MPICH h_vmem questions

Dev dev_hyd2001 at yahoo.com
Wed Aug 2 18:03:20 BST 2006


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""Which rank is allocating how much memory? Is it proper distributed?""

I tried it with allocating the same amount of memory on all the
MPICH processes( thats my understanding , Doing a top on the nodes shows four 
processes with the same name as my program with the same amount of memory.)
it still behaves the same way.



Are you using MPICH with qrsh or shared memory with forks? 

As far as I know I'm using MPICH with qrsh and I also have -V option in the $SGE_ROOT/mpi/rsh
for tight integration.

BTW when this happens the MPICH process gets a sigsegv 11 interrupt.


/Dev


Reuti <reuti at staff.uni-marburg.de> wrote: Am 02.08.2006 um 15:17 schrieb Dev:

> Hi,
>
>       Few questions about h_vmem and MPICH.
>
> Setup
>
> Two Nodes with h_vmem set to requestable and consumable and with  
> its value
> 6.519G when doing a qhost -F | grep h_vmem
>
> Both the nodes have 4 slots each.
>
>
> I have a very simple MPICH program which doesn't do anything useful  
> except mallocing memory in each MPICH process by taking a command  
> line parameter.
>
> Each MPICH process mallocs different amounts of memory based on a  
> command line parameter specified by the user.
>
> I start the MPI program by doing a qsub and requesting for h_vmem  
> and a parallel environment which includes both the nodes mentioned  
> above.
>
> The whole purpose is just to increase my understanding of how  
> h_vmem behaves when launching mpich programs and I'm not yet an  
> expert MPICH programmer.
>
>
>
> I do
>
> qsub -pe mp_pe 8 -l h_vmem=1g submit_mympi.sh
>
> In submit_mympi.sh I ask the MPI program to allocate a total of  
> less than 6G approx( more closer to 6.5 or so )  and everything  
> works fine with the mpich processes distributed between both the  
> nodes.
>
> Then I do
>
> qsub -pe mp_pe 5 -l h_vmem=2g submit_mympi.sh

Which rank is allocating how much memory? Is it proper distributed?  
Are you using MPICH with qrsh or shared memory with forks? - Reuti


> In submit_mympi.sh I ask the MPI program to allocate a total of  
> 6.5G approx and the MPICH processes gets killed.
>
> What I expected in the above case was for the program to run since  
> the total amount of h_vmem requested was more than what  the  
> program tried allocating with 4 mpich processes on each node. 
> ( Definitely the total mallocing attempted on a single node would  
> have been less than 6.5 GB which is the total setting for h_vmem on  
> each node ).
>
> Is this the intended behavior that, even if the total h_vmem  
> requested is more than the total memory which would be used by the  
> job , the job will get killed if the memory allocated is more than  
> the value of h_vmem on the head node?
>
>
> cheers
>
> /Dev
>
>
>
>
>
>
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>
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