Petsc and Slepc with multiple process groups

[Yujie]

Thank you very much, Lisandro. You are right. It look like a little
difficult to "transfer" data from one node to "N" nodes or from N nodes to M
nodes. My method is to first send all the data in a node and to redistribute
it in "N" or "M" nodes. do you have any idea about it? is it time-consuming?
In Petsc, how to support such type of operations? thanks a lot.

Regards,

Yujie

On Wed, Sep 17, 2008 at 5:05 PM, Lisandro Dalcin <dalcinl at gmail.com> wrote:

> A long as you create your SLEPc objects with the appropriate
> communicator (ie. the one obtained with MPI_Comm_split), then all
> should just work. Of course, you will have to make appropriate MPI
> calls to 'transfer' data from your N group to the many M groups, and
> the other way to collect results.
>
>
> On Wed, Sep 17, 2008 at 8:25 PM, Yujie <recrusader at gmail.com> wrote:
> > You are right :). I am thinking the whole framwork for my codes. thank
> you,
> > Lisandro. In Step 3, there are different M slepc-based process groups,
> which
> > should mean M communication domain for Petsc and Slepc (I have created a
> > communication domain for them) is it ok? thanks again.
> >
> > Regards,
> >
> > Yujie
> >
> > On Wed, Sep 17, 2008 at 4:08 PM, Lisandro Dalcin <dalcinl at gmail.com>
> wrote:
> >>
> >> I bet you have not even tried to actually implent and run this :-).
> >>
> >> This should work.  If not, I would consider that a bug. Let us know of
> >> any problem you have.
> >>
> >>
> >> On Wed, Sep 17, 2008 at 7:59 PM, Yujie <recrusader at gmail.com> wrote:
> >> > Hi, Petsc Developer:
> >> >
> >> > Currently, I am using Slepc for my application. It is based on Petsc.
> >> >
> >> > Assuming I have a cluster with N nodes.
> >> >
> >> > My codes are like
> >> >
> >> > main()
> >> >
> >> > {
> >> >
> >> > step 1: Initialize Petsc and Slepc;
> >> >
> >> > step 2: Use Petsc; (use all N nodes in one process group)
> >> >
> >> > step 3: Use Slepc; (N nodes is divided into M process groups. these
> >> > groups
> >> > are indepedent. However, they need to communicate with each other)
> >> >
> >> > step 4: Use Petsc; (use all N nodes in one process group)
> >> >
> >> > }
> >> >
> >> > My method is:
> >> >
> >> > when using Slepc, MPI_Comm_split() is used to divide N nodes into M
> >> > process
> >> > groups which means to generate M communication domains. Then,
> >> > MPI_Intercomm_create() creates inter-group communication domain to
> >> > process
> >> > the communication between different M process groups.
> >> >
> >> > I don't know whether this method is ok regarding Petsc and Slepc.
> >> > Because
> >> > Slepc is developed based on Petsc. In Step 1, Petsc and Slepc is
> >> > initialized
> >> > with all N nodes in a communication domain. Petsc in Step 2 uses this
> >> > communication domain. However, in Step 3, I need to divide all N nodes
> >> > and
> >> > generate M communication domains. I don't know how Petsc and Slepc can
> >> > process this change? If the method doesn't work, could you give me
> some
> >> > advice? thanks a lot.
> >> >
> >> > Regards,
> >> >
> >> > Yujie
> >>
> >>
> >>
> >> --
> >> Lisandro Dalcín
> >> ---------------
> >> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
> >> Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
> >> Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
> >> PTLC - Güemes 3450, (3000) Santa Fe, Argentina
> >> Tel/Fax: +54-(0)342-451.1594
> >>
> >
> >
>
>
>
> --
> Lisandro Dalcín
> ---------------
> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
> Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
> Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
> PTLC - Güemes 3450, (3000) Santa Fe, Argentina
> Tel/Fax: +54-(0)342-451.1594
>
>
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