Re: [bgl-discuss] MPI library on BG/L

[Sameer Shende <sameer@xxxxxxxxxxxxxx>]

Hi Sayaka,
	Would using the PMPI profiling interface help in this case? You'd
implement your own collective MPI functions and do what a tool such as TAU
does - interpose your library between the application and the MPICH
library. Many profiling and tracing tools use this approach to add timing
calls to native MPI libraries without changing the implementation of
MPICH. They internally call the namshifted interface:

#pragma weak MPI_Send = PMPI_Send

int MPI_Send(...)
{ /* original implementation */
}

wrapper library:
int MPI_Send(...)
{
  timer_start();
  int ret_value = PMPI_Send(...);
  timer_stop();
  return ret_value:
}
and while linking in:
-lWrapperlib -lpmpich -lmpich

	If you use this approach and don't invoke the corresponding
PMPI_... call, you'd add your code in the wrapper library. It'll make it
portable to other MPI implementations as well. What do you feel?
	If you are interested in seeing how TAU does this, see
src/Profile/Makefile.wrapper TauMpi.c TauFMpi.c files.
	Thanks,
	- Sameer

On Mon, 5 Sep 2005, Sayaka Akioka wrote:

>
> Hello,
>
> I need your help. But it might be better to send this mail
> to bgl-discuss.
>
> Now I am trying to run my code which utilizes MPI library.
> What I would like to do in my code is to use my own collective
> MPI functions instead of MPI standard collective functions.
> I have done this work on other PC clusters, but now I am trying
> to do the same thing on BG/L. I have trouble getting compiled my
> codes.
>
> For example, in MPIC_Send, MPIC_Recv, MPIC_Sendrecv, MPID_Irecv,
> MPID_Isend, MPID_Send, MPID_Recv, references to functions (their
> name start with "MPIDI_CH3") can not be found. I used mpicc on
> front end machine, under /bgl/BlueLight/ppcfloor/bglsys.
>
> I am guessing this is because I did something wrong, or MPI
> library on BG/L should be the special version. To get my codes
> compiled, what should I do?
>
> I am attaching the error messages.
>
> Thank you,
> Sayaka
>
> --
> Sayaka Akioka
> e-mail: akioka@xxxxxxxxxxx
>

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