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Add bisection test #203
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Add bisection test #203
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Can't you already do that running the sendrecv_perf test, and setting NCCL_TESTS_SPLIT_MASK=(nranks/2)-1? Sure, that only works with nranks being a power of two; maybe your code is more generic. |
Being able to run this test when nranks is not a power of two is actually important to us |
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Add bisection to makefile Add bisection doc in performance.md
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The code is ready to merge from our side |
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int getPeer(int rank, int n_ranks){ | ||
if (n_ranks % 4 == 0) |
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Why is n_ranks % 4 == 0 a special case?
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This allow cross rail bisection for rail-optimized topology
In a bisection, each rank is paired with one other rank called 'peer', they both send and receive N messages, this number is bound to the
agg_iters
parameter.The selection of this 'peer' rank is defined by the
getPeer
function:https://github.com/x41lakazam/nccl-tests/blob/bisection_test/src/bisection.cu#L19