# Tunables for frank-medium (ajgazin/Swift-Qwen3.8-27B-Uncensored-Dynamic-MTP # UD-Q8_K_XL + magnitudedev/Qwen3.8-27B-DSpark-GGUF Q8_0 drafter), mainline llama.cpp # on Dankserver, 2x AMD Radeon AI PRO R9700 (gfx1201). Since 2026-09-16 this # is the SOLE LLM runtime on the box: the vllm-radiance replica pair and its # routing proxy are retired. # # Hardware: two R9700 (Navi 48, RDNA4, 32,624 MiB each), no XGMI, different # IOMMU groups -- every cross-card byte goes over PCIe. The Raphael iGPU # (gfx1036/Radeon 610M) enumerates as HIP device 2 and is hidden below so # nothing can drift onto shared system RAM. # # WHY LAYER SPLIT AND NOT TENSOR (operator call, 2026-09-16): tensor parallel # needs a cross-card allreduce per layer, and this host cannot dispatch one. # RCCL's kernels carry a hidden hostcall-buffer parameter, and ROCr refuses it # on a device without PCIe atomics -- the second card sits behind the B650 # chipset bridges (AtomicOpsCap: Routing-, read-only), so every collective that # touches it dies with hipErrorIllegalState. Measured on this box 2026-09-15 # (llama-bench, pp4096 / tg128, f16 KV, fa on): # # single R9700 1160.9 / 19.42 # layer 2x 1991.2 / 18.76 (859.1 / 17.64 at depth 32768) # tensor 2x 271.8 / 26.26 (no RCCL: butterfly fallback, -7x prefill) # # Layer split distributes layers in order; only the activation at the boundary # crosses the wire, once per forward pass. That is the "pipeline parallelism" # this service wanted, and it needs no collective at all. # # Runtime: mainline llama.cpp master fb27a525 (2026-09-16), gfx1201, built by # scripts/build-llama-rdna4.sh against a private ROCm 7.14.0a20260624 toolchain # that is bundled next to the binary (RPATH $ORIGIN/../lib, no LD_LIBRARY_PATH). # The ref is pinned by TWO features: DFlash2 (ggml-org/llama.cpp#27342 -- the # drafter is detected from its GGUF) and qwen35 MTP. Do not float it. # # Model: ajgazin/Swift-Qwen3.8-27B-Uncensored-Dynamic-MTP-GGUF @ UD-Q8_K_XL, # 29.29 GiB, arch qwen35, Unsloth Dynamic 3.0 (per-tensor types from Unsloth's # own quant of the same size, on Unsloth's importance matrix). Abliteration is # orcarouter's single refusal direction projected out of 131 tensors; the vision # tower is untouched but unused here (text only, see NO_MMPROJ). The file also # carries the model's MTP head (blk.64.nextn.*), so a file-level switch to # --spec-type draft-mtp is available without a second copy in VRAM. # # Drafter: magnitudedev/Qwen3.8-27B-DSpark-GGUF @ Q8_0, 1.27 GiB: 5 layers, # hidden 5120, block-diffusion proposal with the Markov head (dspark). # Decoding stays lossless -- the target verifies every drafted token. Its KV # spans the whole context (see SIZING): unlike DFlash2 it declares no sliding # window, and that is what the tensor split below pays for. # # Architecture (GGUF arch qwen35): 64 layers as 16 x (3 x (Gated DeltaNet -> # FFN) + 1 x (Gated Attention -> FFN)) -- 48 linear-attention layers whose # per-sequence state is CONSTANT-SIZE, 16 full-attention layers at 4 KV heads x # 256 head_dim. A token therefore costs 2 x 4 x 256 x 2 B = 64 KiB of KV at f16 # in the attention layers only, plus ~0.16 GiB per sequence of f32 DeltaNet # state at any depth. # # SIZING, measured (rocm-smi, 2026-09-16). Weights split across the two cards; # the drafter AND its KV ride the second. The loader's compute buffers are part # of what is seen below -- they are allocated at load, not per request: # # CTX_SIZE split GPU 0 GPU 1 headroom on the busier card # 131072 1,1 19.89 GB 24.30 GB 9.9 GB / 31 % (DFlash2) # 262144 1,1 24.72 GB 29.14 GB 5.07 GB / 15 % (DFlash2) <- before # 262144 38,27 28.52 GB 30.71 GB 3.50 GB / 10 % (DSpark) <- deployed # # 262144 is the window the model ships (n_ctx_train) and it fits with room, so # the fleet gets the whole thing; the arithmetic that used to cap this endpoint # at 114688 was the vLLM predecessor's, not this runtime's. If a future change # adds VRAM (a longer drafter, quantized KV, more slots) re-read the numbers # rather than assuming, and prefer CTX_SIZE over --gpu-layers. # # WHY THE SPLIT IS 38:27. The draft context is built with `n_ctx = # llama_n_ctx(ctx_tgt)` (common/speculative.cpp), so the drafter's KV scales # with the target window, and DSpark -- unlike DFlash2, which declared # sliding_window 2048 and cost ~40 MiB -- caches all of it: 5 layers x 2 x 8 kv # heads x 128 dim x 2 B = 20 KiB per position, i.e. 5.0 GiB at 262144. At a # 1:1 split that put ROCm1 at 33.9 GB of 34.2 GB and the draft's first graph # capture died with `ROCm error: out of memory` (in # common_speculative_impl_draft_dflash::process). Handing three target layers # to ROCm0 buys back ~3 GiB of headroom on both cards at the full window. # # EQUALITY WAS TRIED AND REJECTED. 39:26 levels the cards more closely (3.86 / # 4.69 GiB free -- an 0.83 GiB gap, against 2.08 GiB here), but that server # died on its eighth request: the amdgpu driver logged SDMA0 UTCL2 page faults # and the engine surfaced `ROCm error: an illegal memory access was # encountered` -> ggml_abort, i.e. a fault in the cross-card boundary copy, # which is this layer split's hot path. 38:27 has since served the whole e2e # gate plus a burst of varied requests with none. Do not chase an exact # balance: take the skew that fits and leave the drafter's card on the safe # side of the gap. # # WARNING: do not name any variable TEMP, HOST, or GPU_MAX_HEAP_SIZE (HIP reads # those bare vars; 2026-08-13 incident). llama.cpp takes --host/--port/--temp # as flags only. # llama-server: mainline fb27a525 built for gfx1201 by scripts/build-llama-rdna4.sh. LLAMA_BIN=/home/dank/GitPackages/llama.cpp-dflash2/build-rdna4-rocm714/bin/llama-server # Payload, fetched with scripts/download-frank-medium-gguf.sh. MODEL_DIR=/home/dank/models/Swift-Qwen3.8-27B-Uncensored-Dynamic-MTP-GGUF MODEL_FILE=Swift-Qwen3.8-27B-Uncensored-Dynamic-MTP-UD-Q8_K_XL.gguf DRAFT_MODEL_DIR=/home/dank/models/Qwen3.8-27B-DSpark-GGUF DRAFT_MODEL_FILE=Qwen3.8-27B-DSpark-Q8_0.gguf # Fleet identity. 7770 is the fleet's dankserver endpoint; the alias is the id # at /v1/models and what every client asks for. ALIAS=frank-medium BIND_ADDR=0.0.0.0 LISTEN_PORT=7770 # Device placement. HIP_VISIBLE_DEVICES hides the Raphael iGPU (HIP device 2) # so nothing can drift onto shared system RAM; DEVICES is what llama.cpp splits # across, and neither of the two cards has an XGMI link to the other. HIP_VISIBLE_DEVICES=0,1 DEVICES=ROCm0,ROCm1 SPLIT_MODE=layer # Skewed 38:27 rather than 1:1: ROCm1 also carries the drafter and the whole of # its KV, so it must hold fewer target layers for the cards to end level -- at # 1:1 the drafter's card would sit ~9 GiB above the other. This is the measured # point that keeps BOTH cards above a 3 GiB floor at the full window; a tighter # balance was tried and rejected (see SIZING above). TENSOR_SPLIT=38,27 NGL=999 # Auto-fit has no business resizing a context we set explicitly. FIT=off FLASH_ATTN=on # One slot at the model's full configured window (n_ctx_train 262144), which was # measured to fit before it was deployed: see SIZING above. --parallel DIVIDES # --ctx-size between slots, so one slot carries the whole window and a second # concurrent request queues behind it. CTX_SIZE=262144 PARALLEL=1 BATCH_SIZE=2048 UBATCH_SIZE=512 # Threads cover tokenization, sampling and HTTP only: every layer is on a GPU. NUM_THREADS=8 THREAD_BATCH=8 # f16 K/V: an agentic checkpoint is the wrong place to spend KV precision. CACHE_TYPE_K=f16 CACHE_TYPE_V=f16 # Context checkpoints: 0 is the build's default -- no per-slot KV snapshots, so # a re-sent or rewound conversation re-prefills instead of rewinding. Stated # explicitly so the tunable stays visible rather than merely absent. CTX_CHECKPOINTS=0 CACHE_RAM=8192 # Sampling defaults for requests that send none -- the values the vLLM # predecessor served on this endpoint (`--override-generation-config`), so a # client sees no change across the runtime swap. The model card's own # recommendation is temp 1.0 / top_p 0.95; the harness sets its own per model in # models.yml, so this is the floor, not the contract. TEMPERATURE=0.7 TOP_P=0.95 TOP_K=20 MIN_P=0.0 PRESENCE_PENALTY=0.0 # Reasoning on, projected into reasoning_content (deepseek format) with no # budget: the model decides how long to think. REASONING=on REASONING_FORMAT=deepseek REASONING_BUDGET=-1 # Chat template: empty = the one embedded in the GGUF (Qwen3.8's own). CHAT_TEMPLATE_FILE= CHAT_TEMPLATE_KWARGS='{"enable_thinking":true,"preserve_thinking":true}' # Speculative decoding: the DSpark block-diffusion drafter PLUS the draftless # n-gram matcher. DSpark's GGUF carries block_size 7, so at most 6 draft # tokens per verification step (llama.cpp asserts n_max <= block_size - 1). # The drafter rides ROCm1, the card that ends up holding the target's last # layers. SPEC_TYPE=draft-dspark,ngram-mod SPEC_DRAFT_N_MAX=6 SPEC_DRAFT_NGL=999 SPEC_DRAFT_DEVICE=ROCm1 SPEC_DRAFT_TYPE_K=f16 SPEC_DRAFT_TYPE_V=f16 # MTP (the model's own head) vs the drafter -- MEASURED 2026-09-16 (temperature # 0, 1k prompt / 512 out; the autoregressive baseline and both MTP depths were # run against the deployed configuration in one session, same binary, same # prompts): # # none 17.7 tok/s card1 26.07 GB # draft-mtp n=3 32.4 tok/s 58 % accepted card1 29.35 GB # draft-mtp n=7 26.7 tok/s 33 % accepted card1 29.65 GB # draft-dflash 7 43.5 tok/s 41 % accepted card1 29.42 GB # # All four produced IDENTICAL greedy text, so verification is lossless whichever # proposer runs. DFlash2 is worth 2.46x over autoregressive and 34 % over the # best MTP; deeper MTP drafting costs more than it returns (n=7 accepts 33 % of # 147 proposals, n=3 accepts 58 % of 72). The MTP head is not free either: # selecting it loads blk.64.nextn.* and adds ~3.3 GB to the card that holds it, # against 2.06 GB for the drafter's file. Do not switch this without # re-measuring. # # THE TWO CANNOT BE CHAINED. `--spec-type draft-mtp,draft-dflash` dies at load: # context type MTP requested but model doesn't contain MTP layers # failed to create MTP context # A chain has ONE draft context, and MTP builds against whatever model that # context holds -- here the DFlash2 file, which has no MTP layers. MTP's head is # only loaded when MTP IS the draft model ("creating MTP draft context against # the target model ..."), so a chain of the two is a structural dead end, not a # tuning question. See serverAppConfigs-docs/LLM/frank-medium-llamacpp-dflash2.md. # ngram-mod: the draftless n-gram matcher (CPU hash table in host RAM, no VRAM, # no model file, no draft context). It joins the chain unconditionally -- # unlike MTP, which needs a draft context and therefore cannot share one with # DFlash2. Verified on the loaded server: with ngram-mod as the ONLY spec type, # a prose prompt produces ZERO drafts (plain autoregressive) while a # prompt-echo prompt accepts 100 % of them, so its drafts are unmistakable. # # WINDOW MEASURED 2026-09-16 (chain at each window, decode tok/s): # # n_min/n_max prose 1k/512 prompt-echo 1.5k/400 # 48/64 43.9 200.6 <- deployed # 16/32 36.0 161.0 # 8/16 36.2 113.8 # # The long window is the right one, and not only because it wins on echo: a # SHORT window makes the matcher propose on short fragments of ordinary prose, # where the proposals are rejected and the verification still costs -- which is # the "ngram hurts" result the fleet measured on other payloads twice before. # With 48/64 the chain is byte-identical to DFlash2 alone on prose (same 119 # drafts / 49 accepted) and on the identity prompt (70/53). # # Do not shorten these without re-running scripts/bench-spec-ab.py: the # no-penalty property is what makes the chain safe as a default. SPEC_NGRAM_N_MATCH=24 SPEC_NGRAM_N_MIN=48 SPEC_NGRAM_N_MAX=64 # Text only: the server must not autoload a vision tower. Vision stays on # frank-small (Dankclaw, RTX 3090), which is the fleet's image endpoint. NO_MMPROJ=1