Champion model of the FF-LLM line. A 2.02B GPT-2 architecture model fine-tuned through a multi-stage pipeline (pretraining → SFT → distillation → surgical fine-tuning → knowledge repair) for general-purpose factual question answering.
Model overview
Architecture
GPT-2 (causal LM)
Parameters
2.02B
Hidden size
2048
Layers
38
Attention heads
16
Vocab size
50,257
Tokenizer
GPT-2 BPE
Context length
1024 tokens
Precision
bfloat16 (also fp16/fp32 compatible)
License
Apache 2.0
Author
francescofiamingo1
Benchmark performance
MMLU (Massive Multitask Language Understanding)
Evaluated with lm-eval-harness v0.4.11, greedy decoding.
Split
Score
MMLU full (14,042 items)
28.05%
MMLU dev (285 items)
25.61%
Macro-domain breakdown (MMLU full)
Macro
Subjects
Accuracy
STEM
19 subjects
30.70%
Humanities
13 subjects
26.06%
Social Sciences
12 subjects
30.03%
Other (medicine, law, professional)
13 subjects
29.32%
106-bench (custom factual benchmark)
Custom 106-prompt benchmark with strict TRUTH-list scoring:
Category
N
Score
arithmetic
5
5/5 (100.0%)
open-ended
1
1/1 (100.0%)
person
25
22/25 (88.0%)
science
25
21/25 (84.0%)
geography
25
15/25 (60.0%)
format compliance
25
15/25 (60.0%)
TOTAL
106
79/106 (74.5%)
Improvement vs precursors
Model
MMLU full
Δ vs FF_3.13
FF_3 (base, original release)
—
—
FF_3.1 (post-SFT)
26.72%
-1.33pp
FF_3.11 (specialized variant)
25.20%
-2.85pp
FF_3.13 (this model)
28.05%
— champion
Training pipeline — chronological view
The model went through 7 distinct stages of training. Below is the complete history.
Stage 1 — Pretraining
Architecture chosen: GPT-2 (2.02B parameters), trained from scratch on a curated multi-source web + encyclopedic + educational corpus.
~220,000 tokens/sec sustained (100% GPU utilization, all 8 GPUs in parallel)
Framework
PyTorch + DeepSpeed ZeRO-2
Precision
bfloat16
Total pretraining tokens
~90 billion tokens
Wall-clock pretraining time
~5 days continuous (90B / 220K tok/s ≈ 4.7 days)
Pretraining data composition
The pretraining corpus was assembled from 8 distinct sources, organized in two training modules (M1 BASE / Extra and M2 BASE / Extra) with quality-tiered weighting.
Dataset
Module
Type
Quality weight
FineWeb general
M1 BASE
Web
medium
FineWeb 10BT
M1 Extra25
Web high quality
medium
FineWeb EDU
M2 BASE
Educational
high
FineWeb EDU extended
M2 Extra
Educational reasoning
medium
C4 EN
M1 C4
Web filtered
medium
Wikipedia EN
M1 BASE
Encyclopedic
low
Web Clean custom
M1 BASE / Extra
Web filtered
low
News crawl
M1 BASE
Journalistic
low
Mix proportions (approximate)
60–65% FineWeb (various slices: general, 10BT, EDU, EDU extended)
15–20% C4 EN
5–10% Wikipedia EN
5–10% Web Clean custom
~5% News crawl
This mix prioritizes educational content (FineWeb EDU = high weight) and high-quality web text, with encyclopedic and journalistic sources providing factual grounding.
Stage 2 — Supervised Fine-Tuning (SFT)
Objective: general instruction-following + factual knowledge alignment.
Data sources (~860K total examples):
OpenHermes (cleaned)
UltraChat (cleaned)
WildChat (cleaned)
Numina (math reasoning)
OpenThoughts (chain-of-thought)
Eurus (multi-task)
Composition: ~760K core + 100K augmentation examples. Sharded under s3://ff-llm-datasets/sft/shards_v2/.
Stage 3 — Direct Preference Optimization (DPO) — REJECTED
Multiple LoRA fine-tuning attempts were tried for surgical improvements:
LoRA experiment
Examples
Result
LoRA v4b (synthetic instruction)
6,000
marginal, not promoted
LoRA format-only v1/v3
1,779–2,092
catastrophic forgetting (-3 to -4pp MMLU full)
Lesson: LoRA at LR ≥ 5e-4 with template-structured data caused the model to overfit to template patterns rather than learn generalizable behavior. Not used in the final model.
Stage 6 — Surgical Fine-Tuning
Targeted fine-tuning on a small curated set focused on output discipline (yes/no answers, single-letter MCQ, exact-N lists, numeric-only).
Item
Value
Examples
3,000
Path
D:\ff_llm\ff31_surgical.jsonl
Stage 7 — Knowledge Repair Training (produces FF_3.13)
The decisive stage that turned FF_3.11 into FF_3.13.
Dataset composition (16,006 total):
Block
Description
Examples
Block A
MMLU-style MCQ (multiple choice questions across diverse subjects)