fix: add --exclusive to MI355X multi-node sbatch for accurate benchmarks

[cquil11]

Summary

• Add --exclusive flag to sbatch in benchmarks/multi_node/amd_utils/submit.sh to prevent node sharing during multi-node MI355X benchmarks
• Only non-TP8 configs are affected (TP8 already uses all GPUs); perf-changelog updated for all 11 non-TP8 MI355X configs
• Single-node MI355X salloc already has --exclusive; this brings the multi-node path to parity

Test plan

• Run a non-TP8 MI355X multi-node disagg benchmark (e.g. dsr1-fp8-mi355x-sglang-disagg TP4) and verify results are consistent with exclusive node access

🤖 Generated with Claude Code

[cquil11]

Closing in favor of #929 which already covers MI355X.

[claude]

🟡 The first changelog entry has two documentation inaccuracies: pr-link: TBD should be https://github.com/SemiAnalysisAI/InferenceX/pull/932, and the entry description ("multi-node sbatch") incorrectly lists 7 single-node configs (dsr1-fp4-mi355x-atom, dsr1-fp4-mi355x-atom-mtp, dsr1-fp4-mi355x-sglang, dsr1-fp8-mi355x-sglang, gptoss-fp4-mi355x-atom, gptoss-fp4-mi355x-vllm, minimaxm2.5-fp8-mi355x-vllm) that route through salloc, not sbatch. The config-keys list should contain only the 4 -disagg variants affected by the submit.sh change; the single-node configs are already covered by the PR #929 entry at the bottom of the file.

Extended reasoning...

Issue 1 — pr-link: TBD placeholder

The first changelog entry sets pr-link: TBD (line 16) instead of the actual PR URL. The project convention visible throughout the file is either a full URL (https://github.com/SemiAnalysisAI/InferenceX/pull/NNN) or the in-progress placeholder https://github.com/SemiAnalysisAI/InferenceX/pull/XXX. The bare string TBD is the only such occurrence in the entire file. Since this PR is #932, the correct value is https://github.com/SemiAnalysisAI/InferenceX/pull/932.

One verifier noted that the Pydantic model defines pr_link as a plain str with no URL validation, so TBD does pass schema validation. This is accurate — the bug is not tooling-breaking. However, it is a clear inconsistency with every other entry and a straightforward oversight to fix.

Issue 2 — Single-node configs listed under multi-node sbatch description

The only code change in submit.sh adds --exclusive to the sbatch call in the multi-node disaggregated path. Yet the changelog entry lists 11 config keys, 7 of which are single-node configs that never invoke submit.sh:

• dsr1-fp4-mi355x-atom, dsr1-fp4-mi355x-atom-mtp — use salloc in launch_mi355x-amds.sh (the else branch, confirmed in the diff)
• dsr1-fp4-mi355x-sglang, dsr1-fp8-mi355x-sglang — likewise salloc in the else branch
• gptoss-fp4-mi355x-atom, gptoss-fp4-mi355x-vllm, minimaxm2.5-fp8-mi355x-vllm — also single-node salloc path

Only the 4 -disagg configs (dsr1-fp4-mi355x-sglang-disagg, dsr1-fp4-mi355x-sglang-disagg-mtp, dsr1-fp8-mi355x-sglang-disagg, dsr1-fp8-mi355x-sglang-disagg-mtp) actually route through IS_MULTINODE=true into the sbatch path in submit.sh.

Step-by-step proof:

1. In launch_mi355x-amds.sh, the top-level if [[ "$IS_MULTINODE" == "true" ]] branch calls bash "benchmarks/multi_node/${SCRIPT_NAME}", which invokes submit.sh containing the new --exclusive flag.
2. All other configs fall into the else branch which calls salloc --partition=$PARTITION --gres=gpu:$TP --exclusive ... — this salloc --exclusive flag was already added by PR [AMD] Fix slurm command for AMD devices #929.
3. The PR [AMD] Fix slurm command for AMD devices #929 entry at the bottom of perf-changelog.yaml uses "*mi355x*" and "*mi325x*" wildcards, which already match all single-node MI355X configs including every one incorrectly listed in the first entry.
4. Therefore, including single-node configs in the first entry not only has an inaccurate description but also duplicates coverage already provided by the PR [AMD] Fix slurm command for AMD devices #929 entry.

Impact and fix:

Both issues are documentation-only — the actual --exclusive flag in submit.sh is correctly placed and functional. The fix is: (1) update pr-link: TBD to https://github.com/SemiAnalysisAI/InferenceX/pull/932, and (2) remove the 7 single-node config keys from the first entry, leaving only the 4 -disagg configs.