[petsc-users] MPI Derived Data Type and Non Blocking MPI Send/Recieve

[Zhenglun (Alan) Wei]

Dear folks,
      I did more tests, since I want to make sure where I'm wrong.
      As Dr. Smith suggested, I tested my code using OpenMPI and MPICH. 
Both of them have the memory accumulation problem. Therefore, I suppose 
there is a bug in my code. I went into the code, and changed the 
non-blocking MPI communication to blocking one. The memory accumulation 
problem is just gone by itself. However, I have to change it back since 
the blocking MPI communication does not allow me to do massive data 
communication. Now, I'm searching for related topics on non-blocking MPI 
communication.
      Here I cut off those unrelated part of my code and attach the 
communication part here. Could anyone help me to briefly check if there 
is any obvious mistake I made in the program? After unzip the file, 
'./AlanRun' will execute the program.

I really appreciate your help :)
Alan


On 9/6/2012 5:56 PM, Jed Brown wrote:
>
> Numeric data that the solver sees should be stored in Vecs. You can 
> put other scalars in Vecs if you like.
>
> On Sep 6, 2012 5:48 PM, "Zhenglun (Alan) Wei" <zhenglun.wei at gmail.com 
> <mailto:zhenglun.wei at gmail.com>> wrote:
>
>     Dear Dr. Brown,
>          I'm not quite familiar with VecScatter. I just read its
>     explanation; it seems requires that my data is stored as a form of
>     vectors (is it the vector in PETSc?). However, my data are stored
>     as arrays in C program.
>          Is that any problem in MPI or it is likely a problem of my code?
>
>     thanks,
>     Alan
>     On 9/6/2012 5:44 PM, Jed Brown wrote:
>>
>>     Are you familiar with VecScatter?
>>
>>     On Sep 6, 2012 5:38 PM, "Zhenglun (Alan) Wei"
>>     <zhenglun.wei at gmail.com <mailto:zhenglun.wei at gmail.com>> wrote:
>>
>>         Dear All,
>>              I hope you're having a nice day.
>>              I met a memory problem for MPI data communication. I
>>         guess here is a good place to ask this question since you
>>         guys are experts and may experienced the same problem before.
>>              I used the MPI derived data type (MPI_Type_contiguous,
>>         MPI_Type_vector and MPI_Type_indexed) to communicate data for
>>         a simulation of 3D problem. The communication is fine, as I
>>         checked every single data it sent and received. However, the
>>         problem is that the memory keeps increasing while
>>         communication. Therefore, I tested each of these three types.
>>         MPI_Type_contiguous does not have any problem; while
>>         MPI_Type_vector and MPI_Type_indexed have problem of memory
>>         accumulation. I tried to use MPI_Type_free, but it does not
>>         help. Have anyone experienced this problem before?
>>              Would this be related to the non-blocking MPI
>>         communication (MPI_Isend and MPI_Irecv). I have to use this
>>         non-blocking communication since the blocking communication
>>         is extremely slow when it has a lot of data involved in the
>>         communication.
>>              Is there any alternative way in PETSc that could do the
>>         similar work of MPI derived types?
>>
>>         thanks,
>>         Alan
>>
>

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