[I sent this out in June, but did not commit it. So resending. Timeout of Jan
5, 2012. Note that this does not use the GPU Direct RDMA]
WHAT: Add support for doing asynchronous copies of GPU memory with larger
messages.
WHY: Improve performance for sending/receiving of larger GPU messages over IB
WHERE: ob1, openib, and convertor code. All is protected by compiler directives
so no effect on non-CUDA builds.
REFERENCE BRANCH: https://bitbucket.org/rolfv/ompi-trunk-cuda-async-2
DETAILS:
When sending/receiving GPU memory through IB, all data first passes into host
memory.
The copy of GPU memory into and out of the host memory can be done
asynchronously
to improve performance. This RFC adds that feature for the fragments of larger
messages.
On the sending side, the completion function is essentially broken in two. The
first function
is called when the copy completes which then initiates the send. When the send
completes,
the second function is called.
Likewise, on the receiving side, a callback is called when the fragment arrives
which
initiates the copy of the data out of the buffer. When the copy completes, a
second
function is called which also calls back into the BTL so it can free resources
that
were being used.
M opal/datatype/opal_datatype_copy.c
M opal/datatype/opal_convertor.c
M opal/datatype/opal_convertor.h
M opal/datatype/opal_datatype_cuda.c
M opal/datatype/opal_datatype_cuda.h
M opal/datatype/opal_datatype_unpack.c
M opal/datatype/opal_datatype_pack.h
M opal/datatype/opal_datatype_unpack.h
M ompi/mca/btl/btl.h
M ompi/mca/btl/openib/btl_openib_component.c
M ompi/mca/btl/openib/btl_openib.c
M ompi/mca/btl/openib/btl_openib.h
M ompi/mca/btl/openib/btl_openib_mca.c
M ompi/mca/pml/ob1/pml_ob1_recvfrag.c
M ompi/mca/pml/ob1/pml_ob1_sendreq.c
M ompi/mca/pml/ob1/pml_ob1_progress.c
M ompi/mca/pml/ob1/pml_ob1_recvreq.c
M ompi/mca/pml/ob1/pml_ob1_cuda.c
M ompi/mca/pml/ob1/pml_ob1_recvreq.h
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