This commit adds support for performing one-sided operations over
supported hardware (currently Infiniband and Cray Gemini/Aries). This
component is still undergoing active development.
Current features:
- Use network atomic operations (fadd, cswap) for implementing
locking and PSCW synchronization.
- Aggregate small contiguous puts.
- Reduced memory footprint by storing window data (pointer, keys,
etc) at the lowest rank on each node. The data is fetched as each
process needs to communicate with a new peer. This is a trade-off
between the performance of the first operation on a peer and the
memory utilization of a window.
TODO:
- Add support for the accumulate_ops info key. If it is known that
the same op or same op/no op is used it may be possible to use
hardware atomics for fetch-and-op and compare-and-swap.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
