Add accumulate method for PortChannel - #784
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atomicAdd method for PortChannelaccumulate method for PortChannel
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`TriggerData`, `TriggerFlag`, and `TriggerSync` were combinable bits, but the
device API only ever produced five of the seven combinations, and the proxy
tested them with three independent masks. Replace them with one opcode per
operation the API can express:
TriggerNone = 0 TriggerPut = 1 TriggerSignal = 2
TriggerFlush = 3 TriggerPutWithSignal = 4 TriggerPutWithSignalAndFlush = 5
Seven values fit the existing 3-bit field with one spare. `handleTrigger`
becomes a switch that names one operation per case and warns on anything
unknown, so a combination nothing emits is now unrepresentable, and a trigger
whose type field is unset is no longer a valid operation.
The old names are removed rather than redefined. Code that composed them with
`|`, or tested them with `&`, must fail to compile: `TriggerFlush` is 3, which
has the old `TriggerData` bit set, so a mask test would silently misbehave.
No behavior change. mp_unit_tests 29/29 and unit_tests 34/34 on H200.
Add `Connection::accumulate()` and `PortChannel::accumulate()`, which add a 64-bit signed value to remote memory. Unlike `updateAndSync()`, the caller needs to know only its own contribution, not the destination's current value. Carried by the `TriggerAccumulate` opcode, with the operand in the trigger's first word. FIFO readiness now comes from the lap-parity commit bit, so a zero operand traverses the proxy like any other trigger; transport tests interleave zero and nonzero accumulates to cover that path. The addition has to be a real read-modify-write at the destination, which not every transport can do: - IB: any number of writers, via RDMA fetch-and-add. Rejected in no-atomic mode, where the device has no RDMA atomics. - Ethernet: any number of remote writers. The receiving process performs the update, and its connections are serialized against each other; without that a 7-writer fan-in loses ~74% of updates. - CudaIpc on ROCm: any number of writers. The proxy runs a kernel on the connection's stream, which also orders it against a following signal. A kernel there runs even while the caller's kernel spins. - CudaIpc on CUDA: not supported, throws InvalidUsage. The host cannot read-modify-write device memory, and a proxy-launched kernel either cannot be scheduled while the caller's kernel spins (same context) or costs 2391 us per operation (separate context), against 19 us for a plain remote store. Tested on H200 (CUDA 12.9) and MI300X (ROCm 7.2), including an 8-rank fan-in test with 7 concurrent writers into one address.
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Summary
Adds
Connection::accumulate()andPortChannel::accumulate()for remote signed 64-bit addition. UnlikeupdateAndSync(), callers provide only their contribution, allowing concurrent writers to share a counter.The operation uses the
TriggerAccumulateFIFO opcode. Its operand occupies the trigger's first word. The implementation follows the latest FIFO protocol: readiness comes from lap-parity commit bits, so zero-valued operands are valid.Transport support
Validation
Tests cover signed and zero operands, operation ordering, unsupported modes, and multi-rank fan-in across supported transports.
Validated on H200/CUDA 12.9 and MI300X/ROCm 7.2. CI build, lint, docs, CUDA comparison, and completed CodeQL jobs pass.