llama2_7b_chat_remove_50_seed42_jbbmix_calib

llama2_7b_chat_remove_50_seed42_jbbmix_calib

meta-llama/Llama-2-7b-chat-hf compressed with the complete SVD-LLM method (AIoT-MLSys-Lab/SVD-LLM, commit 7538cca98880), run as the authors' code rather than reimplemented. Llama-2 is multi-head, so component/svd_llama.py is the authors' file unmodified (gqa_patched: False); the only adaptation is a compatibility shim that trims the causal mask transformers >= 4.48 builds one column wider than the keys, which upstream's exact-shape assertion rejects.

• Parameters removed: 50% (keeping 50%)
• Realised parameter fraction: 0.4998633824481865
• Pipeline: data whitening -> SVD truncation -> LoRA on the U factors -> merge -> LoRA on the V factors -> merge -> fold to a dense checkpoint
• Parameter update: LoRA r=8, 2 epochs per factor, lr 0.0001, batch 64, on yahma/alpaca-cleaned

What is different about this checkpoint

Only the whitening calibration set. SVD-LLM chooses which singular components to keep by reconstruction importance on calibration data, and the published recipe uses WikiText-2 alone -- a distribution containing no harmful requests. This cell adds JailbreakBench's 100 harmful behaviours (JailbreakBench/JBB-Behaviors, harmful split) to that set, rendered prompt-only (the user turn plus the assistant header, no response, so the corpus does not decide by fiat whether it profiles refusal or compliance).

The WikiText half is the identical get_calib_train_data("wikitext2", 256, seed 42) call the published cells make, so this arm adds sequences rather than replacing any. The harmful prompts are 0.78% of the whitening token budget: 100 behaviours are only 2,653 Llama-2 tokens, and a packed calibration sequence must be exactly 2048 tokens long, so all 100 fit in 2 sequences (54 appear twice as fill). Everything downstream -- truncation, both LoRA stages, the fold -- is unchanged.

Why so small a share can matter: whitening factorises W S = U Sigma V^T with S S^T = E[x x^T], so importance is measured after dividing by S. Directions carrying little calibration energy are amplified in the whitened basis, and adding energy along directions WikiText never excites can move the truncation ranking far more than the token share suggests.

Results

Over-refusal judging is reliable for this cell (XSTest-safe scored fraction 0.98; OR-Bench-Hard-1K scored fraction 0.99).

whitening_compression.json records the calibration set and all 224 per-matrix ranks; build_manifest.json records the full build.

Evaluation

WikiText-2 perplexity; ARC-Easy/Challenge, HellaSwag, WinoGrande, OpenBookQA, PIQA and MathQA zero-shot; AdvBench and StrongREJECT generation judged by cais/HarmBench-Llama-2-13b-cls; over-refusal on XSTest-safe and OR-Bench-Hard-1K judged by allenai/wildguard. All generation uses the chat template, greedy.

Caveats

• Compression at this ratio degrades generation quality, and safety numbers from a degenerate model are not evidence about alignment. Read the over-refusal and reliability lines alongside the ASR. On this cell, harmful-prompt generations are largely coherent, but output on generative benign prompts (the control set is mostly "write a script that ...") degrades noticeably.
• The reference point for "did the calibration change help" is the matched WikiText-only cell at the same removal ratio and seed, built by the same script. That comparison was made in a separate run of the pipeline on other hardware; the two evaluation stacks agree on the uncompressed model to four decimal places, but a same-environment control has not yet been built.
• The model is rank-deficient, not smaller on disk: factors are folded back to dense Llama shapes (W = U @ V), so it loads with stock transformers and needs no custom modelling code.