George,
i digged into the code, and it is now not working as expected :-(
here is a snippet of my test code :
putenv("OMPI_MCA_coll_tuned_bcast_algorithm=1");
putenv("OMPI_MCA_coll_tuned_bcast_algorithm=1");
MPI_Init(&argc,&argv);
MPI_Bcast(out,MAXLEN,MPI_INT,root,MPI_COMM_WOR
This is my understanding of the MPI standard. Obviously some combination of
op and datatype are practically associative and commutative, in which case
the pattern you describe would be legal. Technically, we could add an MCA
parameter to allow the users to specify that the op should be considered a
Thanks George, i will try to find it.
for the second part, and if i read between the lines, that means a
collective operation cannot have non deterministic paths, such as
for (...) MPI_Irecv();
for (...) { MPI_Waitany(); ompi_op_reduce(); }
is that *really* prohibited ? i thought it was "on
There is a mechanism to select the collective algorithm upon communicator
creation. It is not using MPI_T (as this mechanism didn't exist at the
tuned conception), but it behave in a similar manner. You simply update an
MCA param (I do not remember the name and I'm not close to my computer),
and th
Folks,
i was thinking of using the MPI_T interface in order to try within the
same MPI test program *all* the available algo of a given collective.
That cannot currently be done because the mca parameter is registered with
{flag=0, scope=MCA_BASE_VAR_SCOPE_READONLY}
i made a proof of conc
