Frank
4144f0f0e8
ik_llama limits speculative decoding to a single server slot (-np 1) and hard-exits at load if a spec stage is configured with --parallel > 1: "Speculative decoding is currently limited to a single server slot (-np 1)." This service keeps PARALLEL=3 (one slot per user), so set SPEC_TYPE=none to disable speculation. It is a low-parameter MoE (3B active of 35B), so throughput is fine without it. MTP stays disabled. KB and tests updated.
227 lines
10 KiB
Markdown
227 lines
10 KiB
Markdown
---
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type: reference
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title: ik_llama.cpp on Dankserver (Ornith Q6_K)
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description: ikawrakow/ik_llama.cpp replaces upstream llama.cpp for frank-default-small on the RTX 3090. q8_0 KV cache with Hadamard (the fast q8_KV type crashes on this arch at this commit), split-mode none (graph requires >=2 GPUs), speculative decoding disabled (3 parallel slots), and explicit CPU-expert offload. Includes the mandatory CUDA/IQK FA_ALL_QUANTS build flags.
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tags:
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- ikllama
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- llamacpp
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- cuda
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- dankserver
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- moe
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- ornith
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- kv-cache
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- hadamard
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timestamp: 2026-08-26
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---
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# ik_llama.cpp on Dankserver (Ornith-1.5-35B-A3B CRACK)
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> **Active 2026-08-26.** `frank-default-small` switched from upstream
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> llama.cpp (b10121) to `ikawrakow/ik_llama.cpp` (commit `b166e269`) on the
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> RTX 3090. This page documents the build, the mandatory FA build flags, and
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> the MoE / CPU-offload runtime arguments.
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The model is unchanged: `dealignai/Ornith-1.5-35B-A3B-UNCENSORED` (CRACK
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Q6_K), 35B-total / 3B-active MoE-dense hybrid with an MTP head in the GGUF.
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Speculative decoding is **disabled** (ik_llama limits spec to a single slot;
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this service keeps 3 parallel slots). The low-parameter MoE does not need
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it. See [[dealign-ornith-crack]] for the model runbook.
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## Why ik_llama.cpp
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ik_llama.cpp is ikawrakow's llama.cpp fork with heavy CPU + CUDA
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optimizations, IQK/AVX-512 kernels, `--fit` auto-offload, and fast q8_KV
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cache. Dankserver is a CUDA (RTX 3090) + CPU-MoE-offload box, which is
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exactly the supported hybrid the fork targets. Only CPU and CUDA backends
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are fully functional; ROCm / Vulkan / Metal are unsupported upstream.
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## Build recipe (CUDA 13.2 via staged pip toolkit)
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The system CUDA toolkit on Dankserver is **removed** (`nvidia-cuda-toolkit`
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is in `rc` state; no `/usr/local/cuda*`, no `/usr/bin/nvcc`). The CUDA
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13.2 toolkit is installed via **pip** inside the vllm venv at
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`/home/dank/vllm/.venv/lib/python3.12/site-packages/nvidia/cu13/`. A staged,
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self-contained toolchain at `/home/dank/cuda13-stage` adds the unversioned
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`.so` aliases and static libs CMake needs.
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```bash
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# 1. Clone a pinned ik_llama.cpp
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git clone https://github.com/ikawrakow/ik_llama.cpp.git /home/dank/ik_llama.cpp
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cd /home/dank/ik_llama.cpp
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git checkout b166e269 # the version this deployment was built from
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# 2. Configure (stage already symlinks nvcc/include/lib for cu13)
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cmake -B build \
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-DCMAKE_BUILD_TYPE=Release \
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-DGGML_CUDA=ON \
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-DGGML_CUDA_FA_ALL_QUANTS=ON \
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-DGGML_IQK_FA_ALL_QUANTS=ON \
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-DCMAKE_CUDA_ARCHITECTURES=86 \
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-DCMAKE_CUDA_COMPILER=/home/dank/cuda13-stage/bin/nvcc \
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-DCUDAToolkit_ROOT=/home/dank/cuda13-stage \
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-DGGML_NATIVE=ON
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# 3. Build
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cmake --build build --config Release -j 8
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```
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### ⚠️ MANDATORY: always include the FA all-quants flags
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> **Rule.** Any ik_llama.cpp build that serves a quantized KV cache
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> (q8_KV / q8_0 / Hadamard / any non-f16 KV) **MUST** be compiled with
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> BOTH:
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> - `-DGGML_CUDA_FA_ALL_QUANTS=ON` — compiles every K/V cache quant combo
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> into the **CUDA** FlashAttention kernels. Without it, CUDA FA only ships
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> a subset and **errors at runtime** telling you to recompile when a combo
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> (e.g. q8_KV + Hadamard V-cache) isn't present. The RTX 3090 keeps KV on
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> the GPU, so this is the flag that matters here.
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> - `-DGGML_IQK_FA_ALL_QUANTS=ON` — compiles all quant types (Q4_0/Q4_1/
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> IQ4_NL on top of the always-on F16/Q8_0/Q6_0/BF16) into the **CPU/IQK**
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> FA kernels. Relevant because the MoE experts run on the CPU; the KV
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> cache that backs CPU-side attention uses the IQK FA path.
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>
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> These are the old "asymmetrical quants" compile-time gates. On a CUDA
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> host, omitting `GGML_CUDA_FA_ALL_QUANTS` is the #1 way to get a
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> "recompile with GGML_CUDA_FA_ALL_QUANTS" crash at load time.
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`GGML_NATIVE=ON` lets GCC target the host (the Ryzen 7 7700X is Zen4, so
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`-march=native` enables the AVX512 / VNNI IQK kernels automatically —
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verifiable with `system_info: AVX512_VNNI = 1` in the boot log).
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### CUDA stage note
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`/home/dank/cuda13-stage` is the pip `cu13` toolkit plus the symlinks CMake's
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(CUDAToolkit) finder needs (`libcudart.so`, `libcublas.so`, `libcublasLt.so`
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and static `libcudadevrt.a`/`libcudart_static.a`). It also works around the
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CCCL CUDA version skew by defining
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`-DCCCL_DISABLE_CTK_COMPATIBILITY_CHECK` in `CMAKE_CUDA_FLAGS` (the pip
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package ships nvcc 13.2.78 but reports `CUDART_VERSION 13000`, which trips
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a strict header lint). Do not re-run configure without that flag or you get
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a hard compile error.
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## Runtime configuration
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Files: `scripts/serve-frank-small.sh`, `scripts/frank-default-small.env`,
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`scripts/frank-default-small.service` in the repo. The service just calls
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the serve script; the env file holds all tunables.
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### KV cache: q8_0 + Hadamard
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- `CACHE_TYPE_K=q8_0`, `CACHE_TYPE_V=q8_0` — standard 8-bit KV cache type
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(passes `--cache-type-k q8_0 --cache-type-v q8_0`).
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- `K_CACHE_HADAMARD=1`, `V_CACHE_HADAMARD=1` — `--k-cache-hadamard` and
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`--v-cache-hadamard`. The Hadamard transform preserves KV quality at
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8-bit (docs recommend it for quantized KV below Q6_0). Implemented for
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both the CUDA (`ggml-cuda/hadamard.cu`) and CPU (IQK) paths.
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- Flash-attention is **on by default** (no `-fa` flag needed).
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> ⚠️ **Do not use `q8_KV` (fast type) here.** On this commit (`b166e269`)
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> the fast `q8_KV` cache type crashes at model init on this QWEN3MOE/MTP +
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> multimodal arch with a `ggml view` size assertion
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> (`ggml.c:5427: GGML_ASSERT(view_src == NULL || ... data_size + view_offs`)
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> right after the output buffer is created. It loops the service. Plain
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> `q8_0` (and `f16`) work and were smoke-tested with correct output; this
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> config uses `q8_0`. This was isolated empirically by toggling cache type
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> while keeping the override/hadamard flags.
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These keep the 163840-slot / 491520-pool context while roughly halving KV
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cache RAM vs f16.
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### Split mode: none (single GPU)
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- `SPLIT_MODE=none` → `--split-mode none` (the default). Dankserver has a
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single RTX 3090 yet ik_llama rejects `--split-mode graph` on a box with a
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single device:
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> `llama error loading model: It is not possible to use split mode 'graph'
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> with less than 2 devices`
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So `graph` is **not** a harmless no-op on one GPU — it is a hard load
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error (this bit us on the first deploy and loop the service). It also still
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works with the `--override-tensor` expert pins.
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> **Lesson.** ik_llama `--split-mode graph` requires ≥2 devices. On a
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> single-GPU host you must use `none` (or `layer`, which also needs >1).
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> Do not assume `--split-mode graph` degrades gracefully on one GPU.
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### Expert offload (MoE on CPU)
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The expert-offload pattern is unchanged from upstream llama.cpp: the
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`--override-tensor` regex pins the sparse expert (`ffn_*_exps`) tensors to
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the CPU buft, leaving every full-attention block plus blocks 35-40 on CUDA.
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- `OVERRIDE_EXPERT` — the layer-bounded regex (same as before the switch).
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- `OVERRIDE_BUFT=CPU`.
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- `N_GPU_LAYERS=999` — ik_llama `-ngl` / `--gpu-layers` only accepts an
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integer (the literal `all` is rejected). 999 means "load as many tensor
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layers as possible", while the expert override still pins the exps to CPU.
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### Speculative decoding: disabled (3 parallel slots)
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`SPEC_TYPE=none` (passed as `--spec-type none`). Speculative decoding is
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intentionally disabled because ik_llama **limits any speculative stage to a
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a single server slot**: with `--parallel 3` a configured spec stage
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hard-exits at load with
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> `ERR [load_model] Speculative decoding is currently limited to a single
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> server slot (-np 1).` / `n_parallel=3`
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This service keeps **3 parallel slots** (one per user family via
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`PARALLEL=3`), so speculative decoding cannot be used here. MTP stays
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disabled. The model is a low-parameter MoE (3B active of 35B) and does not
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need the speculation it would cost a slot for.
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> **Lesson.** Do not combine speculative decoding with `--parallel > 1` in
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> ik_llama. Either drop to `-np 1` (one slot) and keep a spec stage, or keep
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> multiple slots and set `SPEC_TYPE=none`. For a multi-user service the
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> extra slots win.
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### Flash-attention + sampling
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Flash-attention is **on by default** in ik_llama (`flash_attn=true`), so no
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`-fa`/`--flash-attn` flag is needed. Sampling, thread, batch, context, and
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checkpoint tunables (`TEMPERATURE`, `TOP_K`, `TOP_P`, `MIN_P`, thread,
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`BATCH_SIZE`, `UBATCH_SIZE`, `CTX_SIZE`, `PARALLEL`, `CTX_CHECKPOINTS`,
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`NO_MMAP`) are unchanged and pass straight through.
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## MoE / hybrid-arg reference (not in upstream llama.cpp)
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Several ik_llama knobs matter for a CPU-MoE offload host:
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| flag | meaning | our use |
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|------|---------|---------|
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| `--split-mode graph` | split tensors+graph across devices; strong for MoE; **requires 2+ devices** | single 3090 → use `none`
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| `-ooae` / `--offload-only-active-experts` | default ON: copy **only active** experts RAM→VRAM | keep ON (huge for A3B: few experts active) |
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| `-grt q8_0` | reduce type for inter-GPU data exchange | not needed (single GPU) |
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| `--fit` | auto-offload to fit VRAM | conflicts with `--override-tensor`; do not use together (runtime error) |
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| `-n-cpu-moe N` / `--cpu-moe` | keep MoE weights of first N / all layers on CPU | also conflicts with `--fit`; our `--override-tensor` is finer-grained |
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| `--fit-margin` | VRAM safety margin for `--fit` | only relevant with `--fit` |
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The current deployment uses `--override-tensor` (not `--fit` or
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`--n-cpu-moe`) for the expert offload, so the `--fit`-conflict rules do not
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apply.
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## Rollback
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The previous runtime `upstream llama.cpp b10121` and its binary
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(`/home/dank/llama.cpp/build/bin/llama-server`) are **left untouched**. To
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rollback to the old stack, change `LLAMA_SERVER=` in
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`scripts/frank-default-small.env` back to that path and
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`CACHE_TYPE_K/V` back to `f16` with Hadamard off, and re-enable the ngram
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spec / `--spec-type` flags. The model file is not changed either way.
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## See Also
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- [[dealign-ornith-crack]] — the Ornith Q6_K model run
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- [[Dankserver System Specs]] — the host
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- [[deployment]] — service-scoped git deploy
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## Citations
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- [ikawrakow/ik_llama.cpp README](https://github.com/ikawrakow/ik_llama.cpp) —
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MoE offload guidance and the `--split-mode graph` + CPU-offload warning
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- [ik_llama.cpp docs/build.md](https://github.com/ikawrakow/ik_llama.cpp/blob/main/docs/build.md) —
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build flags incl. `GGML_CUDA_FA_ALL_QUANTS` and `GGML_IQK_FA_ALL_QUANTS`
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- [ik_llama.cpp docs/parameters.md](https://github.com/ikawrakow/ik_llama.cpp/blob/main/docs/parameters.md) —
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q8_KV (PR 208), K/V Hadamard options, `-cuda graphs=0` workaround, and
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`--split-mode graph` MoE note (PR 1080) |