All the collective decisions are done on the first collective on each
communicator. So basically you can change the MCA or pvar before the first
collective in a communicator to affect how the decision selection is made.
I have posted few examples over the years on the mailing list.
George.
On
If you run with "--mca coll_base_verbose 10" it will display a priority list of
the components chosen per communicator created. You will see something like:
coll:base:comm_select: new communicator: MPI_COMM_WORLD (cid 0)
coll:base:comm_select: selecting basic, priority 10, Enabled
Hi Josh,
It makes sense, thanks. Is there a debug flag that prints out which
component is chosen?
Regards,
Luis
On 07/04/2020 19:42, Josh Hursey via devel wrote:
> Good question. The reason for this behavior is that the Open MPI
> coll(ective) framework does not require that every component
Good question. The reason for this behavior is that the Open MPI coll(ective)
framework does not require that every component (e.g., 'basic', 'tuned',
'libnbc') implement all of the collective operations. It requires instead that
the composition of the available components (e.g., basic +
Hello developers,
I am trying to debug the mca choices the library is taking for
collective operations. The reason is because I want to force the library
to choose a particular module and compare it with a different one.
One thing I have notice is that I can do:
mpirun --mca coll basic,libnbc
