The old BTL interface provided support for RDMA through the use of
the btl_prepare_src and btl_prepare_dst functions. These functions were
expected to prepare as much of the user buffer as possible for the RDMA
operation and return a descriptor. The descriptor contained segment
information on the prepared region. The btl user could then pass the
RDMA segment information to a remote peer. Once the peer received that
information it then packed it into a similar descriptor on the other
side that could then be passed into a single btl_put or btl_get
operation.
Changes:
- Added functions to register and deregister memory regions with the
btl. If no registration is needed a btl should set these function
pointers to NULL. These function take over for btl_prepare_src/dst
and btl_free for RDMA operations. The caller should specify the
maximum permissions needed on the memory.
- Changed the function signatures for both btl_put and btl_get. In
place of a prepared descriptor the caller should provide the source
and destination addresses and registration handles as well as a
new callback function. The callback will be provided with the local
address and registration handle, callback context, callback data, and
status. See mca_btl_base_rdma_completion_fn_t in btl.h.
- Added a new btl constraint: MCA_BTL_REG_HANDLE_MAX_SIZE. This
value specifies the maximum size of any btl's registration handle.
- Removed the btl_prepare_dst function. This reflects the fact that
RDMA operations no longer depend on "prepared" descriptors.
- Removed the btl_seg_size member. There is no need to btl's to
subclass the mca_btl_base_segment_t class anymore.
- Expose the btl's put/get limitations with new struct members:
btl_put_limit, btl_put_alignment, btl_get_limit, btl_get_alignment.
- Remove the mca_mpool_base_registration_t argument from the btl_prepare_src
function. The argument was intended to support RDMA operations and is no
longer necessary.
- Remove des_remote/des_remote_count from the mca_btl_base_descriptor_t
structure. This structure member was originally used to specify the remote
segment for RDMA operations. Since the new btl interface no longer uses
desriptors for RDMA this member no longer has a purpose. In addition
to removing these members the local segment structure fields have been
renamed to from des_local/des_local_count to des_segments/des_segment_count.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
f8e15ca83d