On 3/21/2014 10:17 AM, Ross Boylan wrote:
On 3/21/2014 10:02 AM, Jeff Squyres (jsquyres) wrote:
So just to be clear, the C interface for MPI_Testsome is:
int MPI_Testsome(int incount, MPI_Request requests[],
int *outcount, int indices[],
MPI_Status statuses[]);
And your R call is:
mpi_errhandler(MPI_Testsome(countn, request,
&INTEGER(indices)[0],
&INTEGER(indices)[1], status));
I'm assuming request is an MPI_Request object.
It's a pointer to an array of such objects.
static MPI_Request *request;
request=(MPI_Request *)Calloc(REQUEST_MAXSIZE, MPI_Request);
And integer(indices)[0] is where you want the outcount to go, and
then integer(indices)[1] through [value_of_outcount] is where you
want the indices to go, right?
Yes.
If so, then yes, that looks proper.
You'll probably need to look into what's happening in the R wrapper
as to why you're not getting the right answers, sorry.
There was a problem in the R code that cause MPI_Request objects to be
reused before the original request completed.
Things are working much better now, though some bugs remain (not
necessarily related to MPI_Isend or Testsome).
Just for the record, isend in Rmpi is unreliable because the objects
being sent are subject to garbage collection (by R) before the send
completes. I am working on modifications to Rmpi to fix that.
(and yes, the values in the indices[] array should be between 0 and
(incount-1))
I'm getting increasingly suspicious that this could be an integer size
mismatch, maybe from different compilation options. I think R uses 32
bits (even on 64 bit machines) and MPI uses 64, even though both have
type int. R defines
#define INTEGER(x) ((int *) DATAPTR(x))
What should the integer size be for MPI on 64 bit architectures,
specifically linux gcc (Debian 4.4.5-8) 4.4.5?
I think it's still 32 bits and the problems were elsewhere.
Ross
On Mar 21, 2014, at 12:01 PM, Ross Boylan <r...@biostat.ucsf.edu> wrote:
On Fri, 2014-03-21 at 14:11 +0000, Jeff Squyres (jsquyres) wrote:
Is that C or R code?
C.
If it's R, I think the next step would be to check the R wrapper
for MPI_Testsome and see what is actually being returned by OMPI in
C before it gets converted to R. I'm afraid I don't know R, so I
can't really comment on the syntax / correctness of your code snipit.
If it's C -- which I don't think it is, but it *could* be...? -- I
would need to understand your syntax in calling MPI_Testsome
better; e.g., what's &INTEGER(foo)[x]?
allocVector(INTSXP, countn+1) allocates an R vector of integers.
INTEGER(indices) returns the data portion of that structure, where the
actual integers go. The &...[0] get the address of the first location.
PROTECT keeps things from being garbage-collected by R.
The allocation of indices is a cheat: the first location is used for
the
outcount, and the following locations get the actual indices.
status is a pointer to an array of MPI status objects,
The indices should be small integers, shouldn't they? I'm also getting
some large values back.
Ross
On Mar 20, 2014, at 8:39 PM, Ross Boylan <r...@biostat.ucsf.edu>
wrote:
MPI_Testsome seems to have returned successfully, with a positive
outcount, and yet given me a negative index, -4432. Can anyone
help me understand what's going on?
The call is from R, and so there might be a translation issue. My
first thought was that it might be 32 vs 64 bit integers, but both
OMPI and R seem to be using the C int type for the integers.
Here's the inner call:
SEXP mpi_testsome(SEXP sexp_count){
int countn=INTEGER(sexp_count)[0];
SEXP indices;
PROTECT (indices = allocVector(INTSXP, countn+1));
mpi_errhandler(MPI_Testsome(countn, request,
&INTEGER(indices)[0],
&INTEGER(indices)[1], status));
UNPROTECT(1);
return indices;
}
SEXP is an R structure.
OMPI 1.7.4.
Ross Boylan
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