Thanks for digging into this. Can you file a bug? Let's mark it for
v1.3.1.
I say 1.3.1 instead of 1.3.0 because this *only* affects hierarch, and
since hierarch isn't currently selected by default (you must
specifically elevate hierarch's priority to get it to run), there's no
danger that users will run into this problem in default runs.
But clearly the problem needs to be fixed, and therefore we need a bug
to track it.
On Jan 13, 2009, at 2:09 PM, Edgar Gabriel wrote:
I just debugged the Reduce_scatter bug mentioned previously. The bug
is unfortunately not in hierarch, but in tuned.
Here is the code snipplet causing the problems:
int reduce_scatter (...., mca_coll_base_module_t *module)
{
...
err = comm->c_coll.coll_reduce (...., module)
...
}
but should be
{
...
err = comm->c_coll.coll_reduce (..., comm-
>c_coll.coll_reduce_module);
...
}
The problem as it is right now is, that when using hierarch, only a
subset of the function are set, e.g. reduce,allreduce, bcast and
barrier. Thus, reduce_scatter is from tuned in most scenarios, and
calls the subsequent functions with the wrong module. Hierarch of
course does not like that :-)
Anyway, a quick glance through the tuned code reveals a significant
number of instances where this appears(reduce_scatter, allreduce,
allgather, allgatherv). Basic, hierarch and inter seem to do that
mostly correctly.
Thanks
Edgar
--
Edgar Gabriel
Assistant Professor
Parallel Software Technologies Lab http://pstl.cs.uh.edu
Department of Computer Science University of Houston
Philip G. Hoffman Hall, Room 524 Houston, TX-77204, USA
Tel: +1 (713) 743-3857 Fax: +1 (713) 743-3335
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--
Jeff Squyres
Cisco Systems
