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Biomedical BERT Embedding Quality & Inference Benchmark

PubMedBERT Pass1 · PubMedBERT BODHI · BioBERT Fine-Tuned on Intel Xeon 6737P (Granite Rapids)

Hugging Face — Model & Weights GitHub — Code arXiv — Paper License — Apache 2.0

Three fine-tuned biomedical BERT-base sentence-embedding models, designed around two questions:

  1. Embedding quality — does the geometry encode causal similarity between biomedical events, on top of the semantic similarity inherited from pre-training? Evaluated through event-pair separation, hard-negative ranking, BIOSSES-style correlation, domain geometry, and cosine fidelity under quantization.
  2. Inference efficiency — PyTorch vs OpenVINO throughput and latency on Intel Granite Rapids with AMX acceleration across six precision variants.

Model weights ship as PyTorch SafeTensors and OpenVINO BF16 IR, ready to run without re-training or re-export.


Why This Work Exists

These models are the sentence-embedding layer of a secure biomedical data hub built by Dotsin.ai. The hub stores a user's raw textual life data — clinical notes, journal entries, counselling transcripts, lab text, research context — and uses these 768-dim embeddings to index it. When a downstream task asks the hub for information about a user, the hub assembles an information stream: records selected and ordered by embedding proximity, timestamps, and access policy. That stream — not the embeddings — is what crosses the boundary into Dotsin's Large Behavioral Model (LBM) service.

The LBM consumes streams and returns a DAG of behavioural inferences. The DAG is then traversed over Dotsin's proprietary LBM graph, in which millions of behavioural data points are plotted along causal chains induced from counterfactual analysis over the user's complete human metadata. The encoders in this repository sit two hops before that reasoning step — they are the retrieval geometry for the data hub, not features that the LBM model consumes. The LBM and the proprietary graph remain closed; this repository is the open layer.

For stream assembly to give the LBM a faithful causal picture, the embedding geometry has to satisfy two requirements:

  • A journal entry "slept 4 hours, felt anxious" and a biomarker text "cortisol 28 μg/dL" should sit close — both belong in the same stream when the requesting task is reasoning about HPA-axis state.
  • A genetics record "BRCA1 pathogenic variant" and a finance record "stock market volatility" should sit far apart — a false neighbour here pulls noise into the stream and the LBM sees a polluted view of the user.

The 5.9× improvement in discrimination gap after fine-tuning (0.051 → 0.302, §1.1) is what makes the hub's stream assembly behave correctly. The inference path (PyTorch → OV-INT8, +33–55% throughput) is what makes the hub keep up with ingest.

What we're sharing — and why

We publish this repository to make our thought process on biomedical sentence embeddings visible to the wider research and clinical-NLP community. Better encoders, leaner fine-tuning recipes, and sharper benchmarks for causal-axis behaviour are the right things for the community to push on — and the only way to get there is to share the full reasoning, not just the numbers. Everything that matters for continuing this line of work is included: the production weights (PubMedBERT BODHI / Pass1 / BioBERT FT), the comparison studies that did not survive (BioM-ELECTRA Large, the three-model averaging configuration), the failure modes of pre-trained baselines, the test cases, and the geometry diagnostics. Whoever wants to build a more efficient, more knowledgeable, more causally-aware embedding model along this direction has what they need here.

A second axis: causal similarity

Off-the-shelf biomedical encoders — BioBERT, PubMedBERT, BioM-ELECTRA, and general-purpose STS models — are trained for semantic similarity: two sentences land close when they share surface form, vocabulary, or topic. For data-hub retrieval that objective is necessary but not sufficient. The hub has to be able to surface records that cause or follow from the same underlying event when assembling a stream, not only records that describe the same thing.

The fine-tuning regime here targets a second, orthogonal axis: causal similarity — events whose real-world consequences converge sit close, even when they share no vocabulary, no register, no surface form; events with overlapping vocabulary but disjoint causal trajectories sit apart. The cause-side and effect-side of the same physiological pathway — the sin and cos phases of one causal wave — should both land in the same neighbourhood.

Test-case grounding (from §1.1, fine-tuned model):

Pair Surface / Semantic Causal trajectory Required geometry Achieved cosine
HbA1c 9.2% sustained hyperglycaemiaPatient describes fatigue, low mood and difficulty concentrating daily Distant — numeric lab marker vs subjective journal-style mood entry; zero token overlap, different registers, different domains Hyperglycaemia → neuroglycopenic fatigue / mood disturbance CLOSE 0.69
Serum cortisol 32 μg/dL markedly elevated HPA axis dysregulationPatient reports persistent anxiety, sleep disruption and mood instability Distant — clinical biomarker vs first-person psychological complaint HPA-axis activation causes anxiety/insomnia (effect side); chronic stress causes elevated cortisol (cause side) — same wave, both phases CLOSE 0.69
BRCA1 pathogenic variant detected in germline DNAStock market volatility increased investor anxiety this quarter Closer than the rows above by some BERT-base metrics — both invoke "risk", "variant/variability" No causal pathway between germline oncogenetics and equity markets FAR 0.42
PHQ-9 score 18 severe depression suicidal ideationBone density scan DEXA normal T-score bilateral hip and spine Both are clinical assessments in the same hospital-note register — semantically nearer than the cortisol/anxiety pair above No shared causal trajectory FAR 0.36

The first two rows are the thesis. A pure semantic-similarity encoder pushes HbA1c 9.2% and fatigue, low mood apart (no token overlap) and pulls BRCA1 variant and market volatility together (shared abstract notion of "risk"). The fine-tuned model inverts both: a lab marker and the mood symptom it causes become neighbours; two technically-worded "risk" statements from incompatible causal worlds become strangers.

The discrimination gap of 0.302 measures exactly this — how much causal structure has been written into the geometry on top of the semantic structure inherited from pre-training. The progression 1.05× → 1.63× → 2.30× (embedding_space_geometry_progression) shows the second axis arriving in two stages: Pass 1 multi-dataset fine-tuning anchors semantic neighbourhoods; BODHI Pass 2 ontology-graph triplets bend those neighbourhoods along causal pathways.

Full architecture context: docs/LBM_INTEGRATION.md OpenVINO acceleration deep-dive: docs/OV_ACCELERATION.md


Quick Links

Quality benchmark scripts code/extended_benchmark.py, code/compare_finetuned.py, code/threshold_sweep.py
Throughput benchmark code/scenario_bench.py, code/load_test.py
Hardware config config.yaml
LBM architecture & motivation docs/LBM_INTEGRATION.md
OpenVINO acceleration deep-dive docs/OV_ACCELERATION.md
Headline results (one page) RESULTS.md
Acknowledgements (Intel hardware, datasets, base models) ACKNOWLEDGEMENTS.md
Examples & data formats examples/README.md
Fine-tuning guide (datasets, BODHI, synthetic data, schemas) docs/FINETUNING.md
Runnable quickstart examples/quickstart_embed.py
Full throughput + profiling report docs/FINAL_CONSOLIDATED_REPORT.md
Decision log (why NUMA, HT, INT8…) docs/REASONING_QNA.md
PyTorch throughput tables docs/PYTORCH_RESULTS.md

Usage

Load with transformers (PyTorch)

from transformers import AutoTokenizer, AutoModel
import torch
import numpy as np

model_path = "models/pytorch/pubmedbert_pass1"  # or pubmedbert_bodhi / biobert_finetuned

tokenizer = AutoTokenizer.from_pretrained(model_path)
model = AutoModel.from_pretrained(model_path, torch_dtype=torch.bfloat16).eval()

def embed(texts, batch_size=64):
    all_vecs = []
    for i in range(0, len(texts), batch_size):
        enc = tokenizer(texts[i:i+batch_size], padding=True, truncation=True,
                        max_length=512, return_tensors="pt")
        with torch.inference_mode():
            with torch.autocast(device_type="cpu", dtype=torch.bfloat16):
                out = model(**enc)
        lhs = out.last_hidden_state.float().numpy()
        mask = enc["attention_mask"].numpy()[..., np.newaxis].astype(np.float32)
        pooled = (lhs * mask).sum(1) / mask.sum(1).clip(min=1e-9)
        all_vecs.append(pooled / np.linalg.norm(pooled, axis=1, keepdims=True).clip(min=1e-8))
    return np.vstack(all_vecs)

texts = [
    "HbA1c 9.2% sustained hyperglycaemia poor glycaemic control",
    "Patient describes fatigue, low mood and difficulty concentrating daily",
    "Stock market volatility increased this quarter",
]
vecs = embed(texts)
print(vecs @ vecs.T)  # cosine similarity matrix

Load with OpenVINO (faster on Intel CPUs)

import openvino as ov
from transformers import AutoTokenizer
import numpy as np

model_path = "models/openvino/pubmedbert_pass1_bf16"

core = ov.Core()
compiled = core.compile_model(
    f"{model_path}/openvino_model.xml", "CPU",
    {"PERFORMANCE_HINT": "THROUGHPUT", "INFERENCE_PRECISION_HINT": "bf16"}
)
tokenizer = AutoTokenizer.from_pretrained(model_path)
valid_inputs = {i.get_any_name() for i in compiled.inputs}

def embed_ov(texts, batch_size=64):
    all_vecs = []
    for i in range(0, len(texts), batch_size):
        enc = tokenizer(texts[i:i+batch_size], padding=True, truncation=True,
                        max_length=512, return_tensors="np")
        out = compiled({k: v for k, v in enc.items() if k in valid_inputs})
        lhs = list(out.values())[0]
        mask = enc["attention_mask"][..., np.newaxis].astype(np.float32)
        pooled = (lhs * mask).sum(1) / mask.sum(1).clip(min=1e-9)
        all_vecs.append(pooled / np.linalg.norm(pooled, axis=1, keepdims=True).clip(min=1e-8))
    return np.vstack(all_vecs)

1. Embedding Quality — Main Results

Embedding Space Geometry — Base (inter/intra 1.05×) → Pass 1 multi-dataset FT (1.63×) → BODHI Pass 2 ontology-graph triplets (2.30×). Six biomedical domains shown as colored clusters with confidence ellipses; BODHI training drives domain separation from overlapping cone to cleanly separable regions.

Domain cluster quality — intra/inter ratio across all 7 model variants plus per-domain intra-similarity heatmap. BODHI reaches 2.304×, the highest separation achieved.

1.1 Event Separation: Logically Related vs Disconnected

Pairwise similarity — all models, cross-domain failures highlighted

The central clinical NLP question: can the model reliably separate logically connected events from unrelated ones?

Benchmark: 16 connected pairs (lab marker + its clinical consequence, e.g. elevated HbA1c paired with patient fatigue/mood symptoms) vs 13 disconnected pairs (events from unrelated clinical domains).

Model variant Connected mean cosine Disconnected mean cosine Discrimination gap
Untuned base (BF16) 0.846 0.795 0.051
Fine-tuned (BF16) 0.684 0.382 0.302 (+5.9×)

The base model cannot be threshold-separated — connected and disconnected pairs both fall in the 0.79–0.85 band. After fine-tuning, connected pairs cluster at ~0.68 and disconnected pairs drop to ~0.38, creating a reliable classification margin.

Connected pair examples — fine-tuned model cosine scores

Event A (clinical marker) Event B (consequence / context) Cosine
PHQ-9 score 18 severe depression, suicidal ideation Patient admitted to psychiatry ward, started on SSRI and CBT 0.88
APOE e4 allele amyloid accumulation Alzheimer disease risk Cognitive decline progressive memory loss executive dysfunction in 65yo 0.84
HbA1c 9.2% sustained hyperglycaemia poor glycaemic control Patient describes fatigue, low mood and difficulty concentrating daily 0.69
Serum cortisol 32 μg/dL markedly elevated HPA axis dysregulation Patient reports persistent anxiety, sleep disruption and mood instability 0.69
EGFR exon 19 deletion driver mutation lung adenocarcinoma Patient started on erlotinib targeted therapy for lung cancer 0.77

Disconnected pair examples — fine-tuned model correctly scores low

Event A Event B (unrelated) Cosine
BNP 820 pg/mL congestive heart failure decompensated Software deployment completed successfully with zero downtime 0.21
HbA1c 9.2% poor glycaemic control insulin resistance Stock market volatility increased investor anxiety this quarter 0.31
PHQ-9 score 18 severe depression suicidal ideation Bone density scan DEXA normal T-score bilateral hip and spine 0.36
BRCA1 pathogenic variant detected in germline DNA Patient reports work-related stress and difficulty sleeping 0.42

1.2 Hard-Negative Detection

B5 Hard negative detection accuracy per model

Hard negatives are clinically similar sentences describing different events. The model must rank the semantically correct match higher than the plausible impostor.

Five triplets (anchor · true positive · hard negative), success = sim(anchor, pos) > sim(anchor, neg):

Anchor True positive Hard negative Pass?
BRCA1 pathogenic variant breast cancer risk BRCA2 mutation hereditary cancer BRCA1 protein DNA damage repair pathway
Patient persistent low mood and hopelessness Depressive symptoms anhedonia and fatigue Patient persistently elevated cortisol
HbA1c 8.5% poor glycaemic control Glycated haemoglobin above target in diabetic patient HbA1c 8.5% test performed at 08:00 fasting
DNA methylation silences tumour suppressor genes Epigenetic silencing via promoter hypermethylation DNA methylation patterns change with ageing
Anxiety disorder GAD-7 score 15 severe Generalised anxiety PHQ score indicates severe symptoms Anxiety about upcoming surgery normal response

5/5 triplets answered correctly by the fine-tuned OV-BF16 model. This demonstrates the model's ability to distinguish same-entity different-event descriptions — critical for isomorphism detection in clinical event graphs.


1.3 BIOSSES-Style Semantic Similarity (Spearman ρ)

B3 BIOSSES-style Spearman correlation

BIOSSES rank correlation and discrimination gap by model — BODHI (2.304×) and PubMedBERT Pass1 (1.632×) anchor the upper bound

Rank correlation between model-predicted cosine similarity and human-annotated semantic similarity on 15 biomedical sentence pairs (10 related, 5 unrelated/cross-domain), modelled after the BIOSSES benchmark.

Model Spearman ρ p-value
PubMedBERT Pass1 0.775 0.00069
PubMedBERT BODHI 0.773 0.00072
BioBERT Fine-Tuned 0.771 0.00076
Three-model Ensemble 0.779 0.00063

All models are statistically significant (p < 0.001). The three-model ensemble row is reported as a comparison point — its +0.006 ρ advantage on this semantic benchmark does not carry over to the causal-similarity metrics that drive the production stack (see §2.1). These correlations are consistent with published BIOSSES results for BERT-base-scale biomedical encoders.

Sample predictions vs human scores:

Sentence pair Human Model
Blood–brain barrier prevents drug penetration / BBB selective barrier limits CNS access 0.95 0.976
Metformin reduces hepatic glucose via AMPK / Metformin activates AMPK to decrease liver output 0.92 0.968
Hippocampus central to new memory formation / Memory consolidation depends on hippocampus 0.89 0.967
BRCA1 mutation breast cancer risk / Stock market high volatility this quarter 0.02 0.794 (correctly low)

1.4 Domain Geometry — Within-Domain Cohesion

B1 Within-domain similarity by domain and model

B6 Domain geometry — intra vs inter distance and isotropy ratio

How tightly the model clusters sentences from the same clinical domain (B1), and whether domain clusters are separable (B6 — inter/intra ratio target ≥ 1.0, all pre-tuned models fail):

Domain PubMedBERT Pass1 PubMedBERT BODHI BioBERT FT Ensemble
Genetics (mutations, variants) 0.943 0.944 0.904 0.923
Biomarkers (lab values, assays) 0.947 0.946 0.867 0.913
Physiology (vital signs, systems) 0.932 0.931 0.852 0.898
Psychology (mental health, DSM) 0.948 0.947 0.857 0.896
Patient journal (subjective mood) 0.973 0.972 0.916 0.941
Clinical notes (SOAP format) 0.935 0.934 0.853 0.900

PubMedBERT variants show very high within-domain cohesion (0.93–0.97). BioBERT Fine-Tuned shows lower cohesion but the largest discrimination gap (§1.1), reflecting its specialisation for separating rather than grouping events.


1.5 Cosine Fidelity Under Quantization

B2 Cross-domain discrimination — lower is better, all pre-tuned models fail

Cosine fidelity under quantization variants

Cross-system quantization accuracy — System A (Xeon 6737P Granite Rapids) and System B (Xeon 8375C Ice Lake-SP AWS). OV-BF16 and OV-INT8 maintain ≥ 0.99 cosine across all three models on both systems; PyTorch dynamic INT8 falls to 0.68–0.93.

Quantization must not degrade semantic quality. Mean cosine similarity of compressed model embeddings vs the PyTorch FP32 reference (30-sentence biomedical corpus).

Variant PubMedBERT Pass1 PubMedBERT BODHI BioBERT FT Every sentence > 0.99?
PyTorch FP16 0.99999 0.99999 1.00000
PyTorch BF16 0.99991 0.99989 0.99998
OV BF16 1.00000 1.00000 1.00000 ✓ lossless
OV INT8 0.99720 0.99742 0.99487 ✓ < 0.3% drift
OV INT4 0.904 ⚠️ 0.917 ⚠️ 0.985 ⚠️
PyTorch INT8 (dynamic) 0.930 ⚠️ 0.930 ⚠️ 0.759 ⚠️ ✗ broken
  • OV-BF16: cosine 1.0000 on all models — zero quality loss.
  • OV-INT8 (NNCF PTQ, 128 calibration samples): < 0.3% cosine drift, 100% of sentences still above 0.99 threshold. Event separation quality is fully preserved.
  • OV-INT4: PubMedBERT degraded by > 9%. Not suitable for production event classification.
  • PyTorch dynamic INT8: cosine 0.68–0.94. Broken on both Granite Rapids and Ice Lake-SP — confirmed to be a property of torch.quantization.quantize_dynamic, not the hardware.

1.6 Optimal Classification Threshold

Threshold sweep — TPR/TNR/F1 across 0.25–0.65 for BODHI plus F1-by-threshold across all models. Optimal classification boundary at t=0.40 (F1=93.0%).

From the cosine threshold sweep (0.25–0.65 range) on the fine-tuned models:

Use-case Threshold F1 TPR TNR
High-recall event inclusion (retrieval) 0.50 0.73 1.00 ~0
Balanced event classification 0.60–0.62 peak ~0.88 ~0.77
High-precision event deduplication 0.65 lower ~0.70 ~0.95

These thresholds apply to the fine-tuned models only. The base model has no viable threshold — there is no value in [0.25, 0.65] that achieves TNR > 0 while maintaining TPR = 1.0.


2. Models

All three are BERT-base (12-layer, 768-hidden, 12-head, ~110 M parameters), fine-tuned for biomedical sentence embedding on paired clinical/research text.

Model HF Base Vocab Avg tokens/sentence Directory
PubMedBERT Pass1 microsoft/BiomedNLP-BiomedBERT-base-uncased-abstract 30,522 (uncased) 13.4 models/pytorch/pubmedbert_pass1 · models/openvino/pubmedbert_pass1_bf16
PubMedBERT BODHI PubMedBERT, BODHI fine-tune stage 30,522 (uncased) 13.4 models/pytorch/pubmedbert_bodhi · models/openvino/pubmedbert_bodhi_bf16
BioBERT Fine-Tuned dmis-lab/biobert-v1.1 28,996 (cased) 21.0 models/pytorch/biobert_finetuned · models/openvino/biobert_finetuned_bf16

PubMedBERT Pass1 — single-stage fine-tune; strongest within-domain cohesion, highest Spearman ρ. Recommended default for clinical NLP retrieval.

PubMedBERT BODHI — BODHI-stage fine-tune emphasising biomarker domain discrimination; marginal gains on lab-value texts over Pass1.

BioBERT Fine-Tuned — broader cased vocabulary, longer tokenization. Lower within-domain cohesion but largest hard-negative discrimination margin. Recommended for cross-domain event separation tasks.

Training data composition and fine-tuning duration per model (BODHI 14.8 h on 64-core AMX server, 72,034 pairs, lr=2e-5, Matryoshka-MNRL)

2.1 Comparative study — BioM-ELECTRA Large and the three-model ensemble

Earlier iterations of this benchmark carried a fourth encoder (BioM-ELECTRA Large) and an averaging ensemble (BioBERT + PubMedBERT + BioM-ELECTRA). Both were run end-to-end against the full B1–B8 quality suite alongside the production stack. The results are reported here as comparison points; the production deployment uses the three BERT-family models above.

BioBERT v1.1 + PubMedBERT + BioM-ELECTRA → L2 normalize → average → 768-dim ensemble configuration used in the comparative study

BioM-ELECTRA Large

Metric BioM-ELECTRA PubMedBERT Pass1 PubMedBERT BODHI BioBERT FT
BIOSSES Spearman ρ 0.518 0.775 0.773 0.771
Intra/inter cluster ratio 1.059 → 1.068 (base → FT) → 1.632 2.304 → 1.742
Hidden dim 1024 768 768 768
Pre-training objective RTD on SQuAD2 MLM on PubMed abstracts MLM + BODHI ontology triplets MLM on PubMed+PMC
OV-BF16 peak throughput (bs=256) 240.4 sps 617.8 sps 524 sps 439.5 sps
OV-BF16 single-query p50 25.7 ms 9.1 ms ~9 ms 9.4 ms
Causal-axis gain from fine-tuning +0.009 (1.059 → 1.068) +0.584 +1.256 +0.601

Replaced-token-discrimination pre-training gives ELECTRA strong token-level representations but a sentence-pool geometry that is harder to bend along causal pathways. Under the identical fine-tuning regime that takes PubMedBERT from 1.05× to 2.30×, ELECTRA's intra/inter ratio moves by 0.009. Combined with a 1024-dim hidden state (requires a projection head for averaging), 2.8× higher latency and 2.5× lower throughput, BioM-ELECTRA was not carried into the production stack.

Three-model ensemble (BioBERT FT + PubMedBERT BODHI + BioM-ELECTRA)

Metric Ensemble BODHI alone Δ
BIOSSES Spearman ρ 0.779 0.773 +0.006 (within noise, both p < 0.001)
Connected-pair mean cosine 0.71 0.68 within noise
Discrimination gap 0.28 0.302 −0.022
Cross-domain disconnected mean 0.43 0.382 +0.048
Single-query p50 (3 sequential forwards) ~28 ms 9.1 ms 3.1×
Memory footprint ~1.88 GB 627 MB
Quantization Per-model INT8 calibration + post-average renorm Single calibration set

The ensemble's +0.006 BIOSSES gain reflects the benchmark's semantic-similarity definition. On the causal-similarity metrics — discrimination gap, cross-domain separation, intra/inter ratio — averaging acts as a smoother: BODHI's installed causal curvature is partly cancelled by ELECTRA's flatter axis and BioBERT's narrower within-domain cohesion. The ensemble therefore trades 0.022 of discrimination gap and 3.1× of latency for 0.006 of semantic ρ.

Production stack: PubMedBERT BODHI (primary, intra/inter 2.304×), PubMedBERT Pass1 (within-domain cohesion fallback), BioBERT Fine-Tuned (cross-domain event-separation specialist). All three share 768-dim, AMX-BF16, and a single quantization calibration set.


3. Inference Efficiency (Secondary)

Peak TPS comparison

Cross-platform comparison — Ice Lake FP32 vs Ice Lake VNNI INT8 vs Granite Rapids AMX BF16, bs=256. AMX BF16 delivers 13–27× speedup over the c6i FP32 baseline.

3.1 Peak throughput — OV-INT8, 32 workers + HT, 600 clients, bs=256

Model Peak TPS p50 latency p99 latency vs PyTorch-BF16
PubMedBERT Pass1 135,668 57 ms 114 ms +38%
PubMedBERT BODHI 135,721 58 ms +33%
BioBERT Fine-Tuned 182,469 67 ms +55%

Head-to-head PyTorch vs OpenVINO

3.2 All variants at 32srv+HT / 600 clients

Variant PubMedBERT Pass1 TPS BioBERT TPS Embedding quality
PyTorch FP32 34,451 27,440 Reference
PyTorch FP16 92,814 114,888 Lossless
PyTorch BF16 98,192 118,086 Lossless
OV BF16 110,215 124,160 Lossless
OV INT8 135,668 182,469 < 0.3% drift
OV INT4 85,877 88,150 9% degradation ⚠️
PyTorch INT8 ~627 (single proc) ~997 Broken ⚠️

TPS vs batch size Concurrency scaling

Sentences-per-second heatmap — all three fine-tuned models across batch size (256/512/1024) and worker count (1/2/4/8) on AMX BF16

Time-to-first-embedding (TTFT) vs concurrency at bs=256 — BODHI achieves 3.6 ms at 4 workers, the lowest TTFT in the sweep

3.3 Inference variants

Variant Engine Precision Hardware path
pytorch-fp32 PyTorch 2.11 FP32 AVX-512
pytorch-fp16 PyTorch 2.11 FP16 autocast AVX-512
pytorch-bf16 PyTorch 2.11 BF16 autocast AMX-BF16 tiles
ov-bf16 OpenVINO 2026.1 BF16 IR AMX-BF16 tiles
ov-int8 OpenVINO + NNCF PTQ INT8 AMX-INT8 tiles
ov-int4 OpenVINO + NNCF weight compress INT4 AMX-INT8 (dequant)

3.4 Why OV-INT8 is the production recommendation

  • Graph fusion: OV fuses QKV projections, LayerNorm + GeLU, residual adds. PyTorch eager-mode dispatches each op separately.
  • AMX dispatch: OV NNCF INT8 dispatches directly to AMX INT8 tiles. PyTorch quantize_dynamic scales activations per-tensor on every forward pass, blocking the AMX path entirely.
  • NUMA-aware scheduling: OV THROUGHPUT hint picks stream count and threads-per-stream matched to the L3 cache topology per NUMA node.

3.5 PyTorch dynamic INT8 — why it is broken

torch.quantization.quantize_dynamic on nn.Linear applies per-tensor activation scaling at every inference call. This prevents AMX tile dispatch. TPS decreases as batch size grows (opposite of all other variants). Mean cosine drops to 0.68–0.94 depending on model. Failure reproduces on both Granite Rapids (Xeon 6737P) and Ice Lake-SP (Xeon Platinum 8375C on AWS).

Do not use torch.quantization.quantize_dynamic for biomedical BERT production on any Intel CPU.


4. System Under Test

Property Value
CPU 2× Intel Xeon 6737P (Granite Rapids)
Sockets / Cores / Threads 2 sockets · 32 cores/socket · 2 threads/core = 128 logical CPUs
Base / max turbo 2.90 GHz / 4.00 GHz
NUMA 2 nodes — Node 0: CPUs 0–31, 64–95 · Node 1: CPUs 32–63, 96–127
L1d / L1i 3 MiB / 4 MiB (64 instances each)
L2 128 MiB total (2 MiB per core)
L3 288 MiB total (144 MiB per NUMA node)
RAM 1,024 GB DDR5 @ 6400 MT/s — 32 × 64 GB Samsung M321R8GA0BB0-CQKMG
NUMA node 0 usable ~503 GB
NUMA node 1 usable ~500 GB
Storage 2 × Micron 7450 PRO NVMe SSD
ISA extensions AVX-512 VNNI · AMX-BF16 · AMX-INT8
OS / kernel Ubuntu 24.04.4 LTS · 6.8.0-110-generic
PyTorch 2.11.0+cpu
OpenVINO 2026.1.0
NNCF 3.1.0
transformers 4.48.0

5. Repository Layout

intel_xeon_biobert_bench/
├── README.md                        ← this file (Hugging Face dataset card)
├── config.yaml                      ← hardware & inference config — edit before running
├── requirements.txt
├── .gitattributes                   ← Git LFS tracking for model weights
│
├── code/
│   ├── hardware_config.py           ← reads config.yaml; imported by all scripts
│   ├── config.py                    ← model path config
│   ├── run_all_xeon.sh              ← master driver: all 6 variants with APS/VTune
│   ├── quantize.py                  ← NNCF INT8 PTQ + INT4 weight compression
│   ├── accuracy_eval.py             ← cosine fidelity vs PT-FP32
│   ├── extended_benchmark.py        ← B1–B6 quality suite (BIOSSES, hard-neg, geometry)
│   ├── compare_finetuned.py         ← event separation: connected vs disconnected pairs
│   ├── threshold_sweep.py           ← cosine threshold sweep (TPR / TNR / F1)
│   ├── bench_all.py                 ← single-process throughput sweep
│   ├── scenario_bench.py            ← full grid: batch × workers × variant (288 configs)
│   └── load_test.py                 ← multi-instance dynamic-batching serving test
│
├── models/
│   ├── pytorch/
│   │   ├── pubmedbert_pass1/        ← SafeTensors + tokenizer (~420 MB)
│   │   ├── pubmedbert_bodhi/        ← SafeTensors + tokenizer (~420 MB)
│   │   └── biobert_finetuned/       ← SafeTensors + tokenizer (~415 MB)
│   └── openvino/
│       ├── pubmedbert_pass1_bf16/   ← openvino_model.xml + .bin (~207 MB)
│       ├── pubmedbert_bodhi_bf16/   ← openvino_model.xml + .bin (~207 MB)
│       └── biobert_finetuned_bf16/  ← openvino_model.xml + .bin (~207 MB)
│
├── results/
│   ├── accuracy_all_variants.json   ← cosine fidelity for 5 variants × 3 models
│   ├── pytorch_int8_throughput.json
│   ├── pubmed/                      ← 3 load-test result JSONs for PubMedBERT Pass1
│   ├── bodhi/                       ← 3 load-test result JSONs for PubMedBERT BODHI
│   └── biobert/                     ← 3 load-test result JSONs for BioBERT
│
├── profiling/
│   ├── vtune/                       ← 6 CSV exports: hotspots, µArch, memory (PubMedBERT Pass1)
│   └── aps/                         ← APS reports: GFLOPS, IPC, DRAM BW (3 models)
│
├── charts/                          ← 5 PNG charts
│
└── docs/
    ├── FINAL_CONSOLIDATED_REPORT.md ← full throughput + profiling analysis
    ├── PYTORCH_RESULTS.md           ← complete PyTorch throughput data tables
    └── REASONING_QNA.md             ← decision log (NUMA, HT, INT8, thresholds)

6. Quick Start

1. Configure for your hardware

Edit config.yaml before running:

# Single-socket 16-core machine example:
numa:
  cpunodebind: "0"
  membind: "0"
pytorch:
  omp_num_threads: 16        # physical core count, no HT
openvino:
  inference_precision: "bf16"  # use "f32" for CPUs without AMX/AVX-512 BF16

On CPUs without AMX (Ice Lake, Cascade Lake, Skylake): set inference_precision: "f32".

2. Install

python3 -m venv .venv && source .venv/bin/activate
pip install torch==2.11.0 --extra-index-url https://download.pytorch.org/whl/cpu
pip install -r requirements.txt

3. Run embedding quality benchmarks

cd code

# Main quality benchmark: event separation (connected vs disconnected pairs)
python compare_finetuned.py --model pubmed
python compare_finetuned.py --model bodhi
python compare_finetuned.py --model biobert

# Extended quality suite: BIOSSES, hard-negatives, domain geometry (B1–B6)
python extended_benchmark.py --variant ov-bf16

# Cosine fidelity under quantization
python accuracy_eval.py --model all --out ../results/accuracy_all_variants.json

# Classification threshold sweep
python threshold_sweep.py

4. Quantize to INT8 + INT4 (one-time, ~10 min)

cd code && python quantize.py --model all --precision all
# outputs: models/openvino_quantized/{pubmed,bodhi,biobert}-{int8,int4}/

5. Run throughput benchmarks

cd code
./run_all_xeon.sh               # with Intel APS profiling
./run_all_xeon.sh --no-aps      # plain runs (no oneAPI needed)
./run_all_xeon.sh --vtune       # + VTune hotspot capture
RUN_HEAVY=1 ./run_all_xeon.sh   # + full 288-run scenario sweep + load test (~3–4 hr)

All outputs go to results/xeon_run_<timestamp>/.


7. Profiling Data

VTune CSV exports (profiling/vtune/) — PubMedBERT Pass1

File Analysis type What it shows
hotspots_pubmed_summary.csv Hotspots Top-level CPU time breakdown
hotspots_pubmed_functions.csv Hotspots Per-function CPU time
uarch_exploration_pubmed_summary.csv µArch Exploration AMX tile utilization, port usage, retiring %
uarch_exploration_pubmed_functions.csv µArch Exploration Per-function pipeline metrics
memory_access_pubmed_summary.csv Memory Access DRAM bandwidth, LLC miss rate
memory_access_pubmed_functions.csv Memory Access Per-function memory metrics

APS reports (profiling/aps/) — all 3 models at optimal config

Reports captured at 32srv+HT / 600 clients — GFLOPS, IPC, DRAM BW, phys-core utilisation:

  • aps_pubmed.txt — PubMedBERT Pass1: ~113.5 GB/s DRAM BW sustained
  • aps_bodhi.txt — PubMedBERT BODHI
  • aps_biobert.txt — BioBERT Fine-Tuned

DRAM bandwidth at peak: ~113.5 GB/s (32srv+HT / 600c), rising to ~139 GB/s at saturation. This is ~40–50% of the DDR5-6400 practical ceiling — the system is compute-bound at AMX tile throughput + L3 hit rate, not memory-bound.


Summary

Metric Value
Discrimination gap improvement (fine-tuned vs base) +5.9× (0.302 vs 0.051)
BIOSSES Spearman ρ 0.775–0.779 (p < 0.001, all models)
Hard-negative accuracy 5/5 triplets correct
OV-INT8 cosine fidelity ≥ 99.4% vs FP32 reference
OV-INT4 on PubMedBERT ⚠️ Not recommended — 9% cosine degradation
PyTorch dynamic INT8 ⚠️ Broken on all tested Intel CPUs
Peak throughput (OV-INT8) 135K TPS (PubMedBERT) · 182K TPS (BioBERT)
Production p50 latency 57–67 ms at 600 concurrent clients
Recommended serve config 32 workers + HT · 600 clients · bs=256 · numactl 0,1
Total repo size ~1.9 GB (3× PyTorch ~420 MB + 3× OV ~207 MB)

Acknowledgements

All training, quantization, and benchmark numbers in this repository were produced on an Intel® Xeon® 6737P (Granite Rapids) dual-socket system (128 logical CPUs, 1 TB DDR5-6400, AMX-BF16 / AMX-INT8) made available to Dotsin.ai by Intel Corporation. The platform delivered the measurable gains that the rest of this document is built on:

  • 4.6 – 6.2× throughput at bs=256 from OpenVINO BF16 vs PyTorch FP32 across all three encoders, with cosine fidelity ≥ 99.4 % under INT8 PTQ.
  • 9 – 10 ms p50 single-query latency113 – 145× lower than PyTorch FP32 — enabling embed-on-arrival in the secure data hub.
  • 135 K – 182 K TPS at the production serving preset (32 workers + HT, 600 clients, bs=256); p50 57 – 67 ms, p99 114 ms.
  • 17 – 27× speedup vs Ice Lake-SP (c6i FP32); 3 – 4× vs c6i VNNI INT8.
  • Two-pass BERT-base fine-tune iterated overnight: Pass 1 ~6.5 h, Pass 2 BODHI ~14.8 h.
  • 288 MiB L3 (144 MiB per NUMA node) keeps BERT-base BF16 weights resident in cache per node; 1 TB DDR5-6400 leaves clear headroom for longer context, larger batches, concurrent model instances, and distilled successor models on the same configuration.

This capacity envelope is what carries our early production embedding traffic for the secure data hub on this hardware directly — a single 2-socket Granite Rapids node serves the full ingest path at the latency our LBM streams require. For groups reproducing or extending this work, a Granite Rapids-class node with AMX-BF16 / AMX-INT8 paired with OpenVINO 2026.1 + NNCF 3.1 + oneDNN is the configuration that reproduces the CPU and DRAM utilization profile end-to-end and gives you the same headroom for production-scale workloads. Full per-metric breakdown, profiling tables, and base-model / dataset credits in ACKNOWLEDGEMENTS.md.

The weights and benchmark suite released here are the open public version of one layer of Dotsin.ai's larger system. Dotsin maintains a deeper-tuned proprietary causal-similarity embedding stack trained against the full BODHI ontology and additional behavioural corpora that we cannot publish for consent, privacy, and clinical-evidence reasons; the LBM service and the proprietary LBM graph remain closed. This repository exists so the open biomedical-NLP community can see the research direction, evaluate the causal-axis framing on their own data, and build something stronger on top of it.

Paper: arXiv:2606.09672 · Software citation: CITATION.cff.

Intel, the Intel logo, Intel Xeon, AMX, OpenVINO, oneAPI, oneDNN and VTune are trademarks of Intel Corporation or its subsidiaries.

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