Ornith-1.0-35B-GGUF-llamacpp-tp1 / benchmarks /llamacpp-longctx-ttft.md
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Add long-context TTFT chart + data (512-32768 tok, 3 quants); pin llama.cpp commit 050ee92
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Ornith-1.0-35B GGUF Long-Context TTFT

Date: 2026-06-28

How prefill latency (time-to-first-token) scales with prompt/context length on a single GPU, single stream. This complements the short-context throughput sweep in llamacpp-quant-benchmarks.md (which fixes n_ctx=512/slot and uses ~23-token prompts).

Config

  • Backend: local llama.cpp CUDA server, commit 050ee92d04c2e1f639025786dea701c70e7d4204.
  • GPU/driver: NVIDIA RTX PRO 6000 Blackwell Max-Q Workstation Edition, driver 580.159.03.
  • Mode: single GPU, tp=1, CTX_SIZE=131072, PARALLEL=1, n_ctx/slot=131072, REASONING=off, CACHE_RAM=0.
  • Method: per context length, prompts truncated to the exact token count, 64-token generations, deterministic; one warm-up discarded, then ≥20 requests measured.
  • Validation: all 3 quants have 140 rows, 0 failed requests, exact prompt token counts, no skipped contexts.

Results — p95 / p50 TTFT (ms) and decode tok/s

Context tokens Q4_K_M p50 Q4_K_M p95 Q4_K_M tok/s IQ4_XS p50 IQ4_XS p95 IQ4_XS tok/s MTP-graft p50 MTP-graft p95 MTP-graft tok/s
512 91.8 94.1 188.3 87.1 88.7 177.4 86.0 87.8 184.0
1024 169.6 172.2 145.8 159.9 161.6 139.9 157.6 159.0 155.9
2048 341.8 346.1 97.9 316.1 318.7 112.0 307.6 308.9 113.9
4096 699.2 702.2 67.2 647.0 653.4 70.7 625.7 631.3 69.0
8192 1447.5 1458.0 33.7 1342.9 1348.5 39.8 1297.4 1304.0 40.9
16384 3009.7 3030.4 19.5 2793.2 2804.0 20.9 2709.8 2737.3 21.5
32768 6302.4 6313.0 9.7 5829.9 5853.1 10.5 5673.5 5696.6 10.7

TTFT grows roughly with context length (prefill cost), reaching ~6.3 s at 32k tokens for Q4_K_M. The IQ4_XS body and the IQ4_XS-MTP graft prefill slightly faster than Q4_K_M at every length (e.g. 5696.6 vs 6313.0 ms p95 at 32k), and decode tok/s falls from ~180–190 at 512 tokens to ~10 at 32k as the KV cache grows.

Raw artifacts

Single-stream (PARALLEL=1) long-context runs:

  • benchmarks/raw/llamacpp-q4-k-m-longctx-c1.jsonl
  • benchmarks/raw/llamacpp-iq4-xs-longctx-c1.jsonl
  • benchmarks/raw/llamacpp-iq4-xs-mtp-graft-headq6-longctx-c1.jsonl

Each row carries prompt_tokens and ttft_s in the same schema as the other benchmarks/raw/*.jsonl files.