Qwen 3.5 397B-A17B · Speculative Decoding

MI355X BF16: MTP vs Off Speculative Decoding

Speculative decoding comparison of MTP versus Off on MI355X BF16 (AMD CDNA 4) running Qwen 3.5 397B-A17B. Throughput, cost, and interactivity differences across LLM workloads. Use the chart controls below to switch sequences and metrics — same interactions as the main inference chart.

MTP acceptance-rate comparability

MTP acceptance-rate implementations differ across inference engines. Points from different engines are not directly comparable on the same curve — throughput and cost at matched interactivity may reflect engine-level differences rather than pure speculative decoding gains. Interpret cross-engine comparisons with caution.

At 78 tok/s/user on Qwen 3.5 397B-A17B (MI355X BF16), MTP delivers 786 tok/s/GPU at $0.52 per million tokens; Off delivers 339 tok/s/GPU at $1.19. MTP is 129% cheaper per token; MTP delivers 132% more tok/s/GPU. Speculative decoding accepts draft tokens to reduce per-token latency — gains vary by workload and prompt distribution.

MTP posts 732 tok/s/GPU for $0.56 per million tokens at 86 tok/s/user on Qwen 3.5 397B-A17B (MI355X BF16); Off posts 254 tok/s/GPU for $1.60. MTP is 187% cheaper per token; MTP delivers 188% more tok/s/GPU. Draft-token acceptance rates determine whether speculative decoding helps or hurts at a given concurrency level.

Throughput at 95 tok/s/user on Qwen 3.5 397B-A17B (MI355X BF16): MTP hits 648 tok/s/GPU, Off hits 164. Per-million costs land at $0.64 and $2.56 respectively. MTP is 301% cheaper per token; MTP delivers 295% more tok/s/GPU. Speculative decoding trades extra compute on draft tokens for fewer decoding steps — the payoff depends on sequence length and batch size. (Numbers reflect this URL's pinned 1k/1k · bf16 workload — changing sequence or model updates both the table and chart; the table stays pinned to this page's precision, so precision toggles in the controls affect the chart only.)

Qwen 3.5 397B-A17B: MI355X BF16 MTP versus Off speculative decoding comparison at matched interactivity levels
MI355X BF16 MTP versus Off speculative decoding comparison for this page's canonical default workload.
Interpolated from real benchmark data. Edit target interactivity values below to compare at different operating points.
Metric
Interactivity (tok/s/user)
Interactivity (tok/s/user)
Interactivity (tok/s/user)
Throughput (tok/s/gpu)
MTP:785.7Off:339.1
MTP:731.6Off:253.8
MTP:647.6Off:164.1
Cost ($/M tok)
MTP:$0.518Off:$1.188
MTP:$0.556Off:$1.596
MTP:$0.638Off:$2.560
tok/s/MW
MTP:296494Off:127955
MTP:276072Off:95789
MTP:244392Off:61913
Concurrency
MTP:~87Off:~18
MTP:~50Off:~12
MTP:~29Off:~7

Inference Performance

Inference performance metrics across different models, hardware configurations, and serving parameters.

Vendor:
Aggregation:
Spec Decoding: