[AMD/Hyperloom] Tune dsr1-fp8-mi355x-sglang: --num-continuous-decode-steps 4 → 8

[lishuoshuo-amd]

Description

Tune --num-continuous-decode-steps from 4 to 8 for DeepSeek-R1-0528 FP8 on MI355X (SGLang).
Increasing continuous decode steps reduces prefill/decode scheduling overhead, lowering per-token latency (TPOT) and improving overall throughput.

Changes

• benchmarks/single_node/dsr1_fp8_mi355x.sh: --num-continuous-decode-steps 4 → 8
• perf-changelog.yaml: Added changelog entry

Performance Results

Hyperloom CI Optimization Report (conc=64, 1k/1k)

Metric	Baseline	Optimized	Change
Output Throughput (per GPU)	311.65 tok/s	331.22 tok/s	+6.28%
TPOT	24.46 ms	23.01 ms	-5.93%
TTFT	581.20 ms	528.52 ms	-9.07%
vs InferenceX Official	+0.50%	+6.81%

Full Parameter Sweep (12 points, 0 failures)

Verified across the complete (tp, conc, isl, osl) search-space from amd-master.yaml:

ISL/OSL	TP	Conc	Baseline (tok/s)	Optimized (tok/s)	Gain
1k/1k	8	4	399.90	417.60	+4.43%
1k/1k	8	8	729.10	750.26	+2.90%
1k/1k	8	16	1140.92	1173.48	+2.85%
1k/1k	8	32	1683.81	1739.49	+3.31%
1k/1k	8	64	2614.64	2654.50	+1.52%
8k/1k	4	32	770.98	821.53	+6.56%
8k/1k	4	64	991.61	1031.77	+4.05%
8k/1k	8	4	310.30	366.00	+17.95%
8k/1k	8	8	625.61	636.92	+1.81%
8k/1k	8	16	902.98	925.49	+2.49%
8k/1k	8	32	1213.94	1279.19	+5.38%
8k/1k	8	64	1664.40	1709.37	+2.70%

Average gain: +4.7% — positive improvement across all parameter combinations with no regression.

Baseline Validation Against InferenceX Official

Conc	Official (tok/s/GPU)	Our Baseline (tok/s/GPU)	Diff
4	49.82	49.99	+0.3%

Baseline aligns within <1% of official InferenceX data, confirming test environment reliability.

Note: All throughput numbers in this PR refer to output (decode) token throughput, never total. The "Optimization Report" and "Baseline Validation" tables show per-GPU values; the "Full Parameter Sweep" table shows aggregate (TP-summed) values from raw SGLang output_throughput. Per-GPU = aggregate / TP. Gain percentages are unit-invariant.

Related Issue

Automated optimization by Hyperloom CI.

Type of Change

• Configuration change

Checklist

• I have tested my changes locally
• I have updated documentation if necessary
• If I changed a container image or config, I have already updated perf-changelog.yaml

[claude]

Claude Code Review

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[lishuoshuo-amd]

@claude review

[billishyahao]

cc @Duyi-Wang