This commit is a large update to the osc/rdma component. Included in
this commit:
- Add support for using hardware atomics for fetch-and-op and single
count accumulate when using the accumulate lock. This will improve
the performance of these operations even when not setting the
single intrinsic info key.
- Rework how large accumulates are done. They now block on the get
operation to fix some bugs discovered by an IBM one-sided test. I
may roll back some of the changes if the underlying bug in the
original design is discovered. There appear to be no real
difference (on the hardware this was tested with) in performance so
its probably a non-issue. References #2530.
- Add support for an additional lock-all algorithm: on-demand. The
on-demand algorithm will attempt to acquire the peer lock when
starting an RMA operation. The lock algorithm default has not
changed. The algorithm can be selected by setting the
osc_rdma_locking_mode MCA variable. The valid values are two_level
and on_demand.
- Make use of the btl_flush function if available. This can improve
performance with some btls.
- When using btl_flush do not keep track of the number of put
operations. This reduces the number of atomic operations in the
critical path.
- Make the window buffers more friendly to multi-threaded
applications. This was done by dropping support for multiple
buffers per MPI window. I intend to re-add that support once the
underlying performance bug under the old buffering scheme is
fixed.
- Fix a bug in request completion in the accumulate, get, and put
paths. This also helps with #2530.
- General code cleanup and fixes.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This commit fixes the following bugs:
- Allow a btl to be used for communication if it can communicate with
all non-self peers and it supports global atomic visibility. In
this case CPU atomics can be used for self and the btl for any
other peer.
- It was possible to get into a state where different threads of an
MPI process could issue conflicting accumulate operations to a
remote peer. To eliminate this race we now update the peer flags
atomically.
- Queue up and re-issue put operations that failed during a BTL
callback. This can occur during an accumulate operation. This was
an unhandled error case.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This commit adds support for using network AMOs for MPI_Accumulate,
MPI_Fetch_and_op, and MPI_Compare_and_swap. This support is only
enabled if the ompi_single_intrinsic info key is specified or the
acc_single_interinsic MCA variable is set. This configuration
indicates to this implementation that no long accumulates will be
performed since these do not currently mix with the AMO
implementation.
This commit also cleans up the code somwhat. This includes removing
unnecessary struct keywords where the type is also typedef'd.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This commit fixes a bug that occurs when ranks are either not mapped
evenly or by something other than core.
Fixesopen-mpi/ompi#1599
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
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>
