A balanced traffic pattern for AG minimal.

[llongTT]

Ticket

Link to Github Issue

Problem description

AG minimal has low fabric utilization, especially for device ring = 4 cases.
WAN 2.2 model perf requires AG to reach 92% fabric utilization to achieve the target.

What's changed

1. Balance the packet traffic between forward worker and backward worker such that they split the last slice. It saves 25% of fabric latency by going from "2 slice forward, 1 slice backward" to "1 and half slice both forward and backward" in device ring = 4.
2. If balanced traffic feature enabled, also split the local writes half/half, to reduce the noc traffic on backward worker.
3. Extend the feature to all device rings >2 and ring size even cases.

Checklist

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• New/Existing tests provide coverage for changes

Model tests

If your changes cover model-related code, you should run tests corresponding to affected models and platforms (Single card, T3K, Galaxy). "Choose your pipeline" workflows facilitate running multiple kinds of tests in a single run. Each offers models-mandatory and models-extended presets.
The former includes a minimal set of tests, to be run always. The latter extends that with additional ones - use your best judgement in deciding which is the most appropriate for your PR.

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  • models-mandatory preset (runs: Device perf regressions and Frequent model and ttnn tests)
  • models-extended preset (runs: the mandatory tests, plus Demo and Model perf tests)
  • other selection - specify runs

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  • models-mandatory preset (runs: Unit tests)
  • models-extended preset (runs: the mandatory tests, plus Demo and Model perf tests)
  • other selection - specify runs

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  • models-mandatory preset (runs: Quick tests)
  • models-extended preset (runs: the mandatory tests, plus Demo and Model perf tests)
  • other selection - specify runs