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Subject: [OMPI devel] neighborhood collectives issues
From: Jeff Squyres (jsquyres) (jsquyres_at_[hidden])
Date: 2013-09-27 09:01:01


On Sep 27, 2013, at 3:27 AM, George Bosilca <bosilca_at_[hidden]> wrote:

> The addition of the neighborhood collectives to the mca_coll_base_comm_coll_t structure increased the size of the ompi_communicator_t structure over the limit of the predefined padding (PREDEFINED_COMMUNICATOR_PAD). This is not a small change, it will break the ABI with all past version of Open MPI.

This is going to be problematic for putting this in 1.7.4.

Nathan: is there another way? Perhaps even just a stopgap way for the 1.7/1.8 series, and we can keep the "real" way for 1.9+? I.e., perhaps:

1. keep PREDEFINED_COMMUNICATOR_PAD at current value for v1.7.x/1.8, but use a secondary pointer system (which won't be *too* painful; the algorithms are all simple/not optimized, anyway)

2. increase PREDEFINED_COMMUNICATOR_PAD on the trunk for v1.9+ (we might want to increase it more than it is already increased, so that we actually have some breathing room for 1.9+)

> I pushed a temporary commit to allow the trunk to be built, but we might want a better solution.

Thanks George.

> There a re a new warnings:
> ../../../../../ompi/ompi/mca/coll/libnbc/coll_libnbc_component.c: In function 'libnbc_comm_query':
> ../../../../../ompi/ompi/mca/coll/libnbc/coll_libnbc_component.c:196:48: warning: assignment from incompatible pointer type [enabled by default]
> ../../../../../ompi/ompi/mca/coll/libnbc/coll_libnbc_component.c:197:49: warning: assignment from incompatible pointer type [enabled by default]
> ../../../../../ompi/ompi/mca/coll/libnbc/coll_libnbc_component.c:198:47: warning: assignment from incompatible pointer type [enabled by default]
> ../../../../../ompi/ompi/mca/coll/libnbc/coll_libnbc_component.c:199:48: warning: assignment from incompatible pointer type [enabled by default]
> ../../../../../ompi/ompi/mca/coll/libnbc/coll_libnbc_component.c:200:48: warning: assignment from incompatible pointer type [enabled by default]

Nathan: please fix.

-- 
Jeff Squyres
jsquyres_at_[hidden]
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