On Tue, 29 Nov 2011, George Bosilca wrote:

These two functions target at defining a memory layout (contiguous or not) that 
can be target for a one-sided communication. I don't see why there is a need to 
know what type of communication that will be … What is so different in the 
xpmem that requires the memory to be prepared based on the operations that will 
follow?

This would be for the ugni btl, not xpmem. Some uGNI rdma operations do not 
require registration (FMA put). If we know the type of operation at prepare_src 
we can avoid registering memory in these cases.

Moreover, the prepare_src is used outside the context of one-sided, in the send 
protocol. How do you plan to address send operations?

Send operations can be detected by neither MCA_BTL_DES_PUT or MCA_BTL_DES_GET 
being set or a non-zero reserve value (which some btls already use).

-Nathan

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