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Subject: Re: [OMPI users] [Fwd: mpi alltoall memory requirement]
From: viral.vkm_at_[hidden]
Date: 2009-04-23 03:12:11

Thanks for your response.
However, I am running
mpiexec .... -ppn 24 -n 192 /opt/IMB-MPI1 alltaoll -msglen /root/temp

And file /root/temp contains entry upto 65535 size only. That means
alltoall test will run upto 65K size only

So, in that case I will require very less memory but then in that case also
test is running out-of-memory. Please help someone to understand the
Or do I need to switch to some algorithm or do I need to set some other
environment variables ? or anything like that ?

On Apr 22, 2009 6:43pm, Ashley Pittman <ashley_at_[hidden]> wrote:
> On Wed, 2009-04-22 at 12:40 +0530, vkm wrote:

> > The same amount of memory required for recvbuf. So at the least each

> > node should have 36GB of memory.

> >

> > Am I calculating right ? Please correct.

> Your calculation looks correct, the conclusion is slightly wrong

> however. The Application buffers will consume 36Gb of memory, the rest

> of the application, any comms buffers and the usual OS overhead will be

> on top of this so putting only 36Gb of ram in your nodes will still

> leave you short.

> Ashley,