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Subject: Re: [OMPI users] [Fwd: mpi alltoall memory requirement]
From: viral.vkm_at_[hidden]
Date: 2009-04-23 08:51:02


or any link which helps to understand system reuirement for certain test
scenario ..

On Apr 23, 2009 12:42pm, viral.vkm_at_[hidden] wrote:
> Hi
> 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
> scenario.
> 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,
> >
> >
> >