SACHIN MAHESH · BERKELEY, CA

Turning constraints
into architecture.

I build AI systems that do more with the hardware at hand. Studying EECS + Business in UC Berkeley’s M.E.T. program; building independently across models, GPU kernels, and practical engineering.

01 / FEATURED WORKINDEPENDENT RESEARCH · NOVEMBER 2026
GPU SYSTEMS / QUANTIZATION / KERNEL ENGINEERING

A Radeon.
Reconsidered.

Rotated INT4 inference. From 4B to 27B.

A complete GPTQ-INT4 inference path in llama.cpp: native RDNA3 matrix instructions, custom attention and gated-delta-net kernels, and a 4B decode graph cut from 847 to 236 launches per token. Now demonstrated on Qwen3.5-4B, Qwen3.5-9B, and Qwen3.8-27B.

11,012 tok/s

Qwen3.5-4B prefill · pp512 · fast

200.6 tok/s

Qwen3.5-4B decode · tg128

50.1 tok/s

Qwen3.8-27B decode · no MTP

From the instruction to the whole model.

Block-Hadamard rotations tame activation outliers; GPTQ quantizes the rotated weights. Custom WMMA kernels then use RDNA3’s INT4 pipeline directly, with fused operations across prefill and decode.

The pipeline scales to 27.8 billion parameters on one 20 GB card. At 27B, the reported fast result is 2,013 tok/s prefill and 50.1 tok/s decode: 2.27× and 1.53× the stock 7900 XT. The best recorded decode reaches the report’s estimated weight-bandwidth ceiling.

RDNA 3 pushed to the limits — report cover by Sachin Mahesh
QWEN3.5-4B / PRESET COMPARISONRX 7900 XT · 20 GB
Prefill throughputtokens/s · higher is better
Q4_K_M baseline5,477
Rotated INT4 · fast11,012
Prefill speedup
2.01×
Decode
200.6 tok/s
Perplexity change vs BF16
+8.67%
KL divergence vs BF16
0.0969

Fast uses 4-bit activations for 2.01× prefill throughput, with a larger quality cost. Decode always uses 8-bit activations.

Stock Qwen3.5-4B; same checkpoint, GPU, and build. Q4_K_M: 145.2 tok/s decode, +2.00% perplexity, 0.0278 KLD. WikiText-2 evaluation. Measurements and limitations in the report.

ONE RX 7900 XT / THREE MODEL SIZES

The gains scale
with the model.

Against stock Q4_K_M on the same card, fast prefill reaches 2.01× at 4B, 2.20× at 9B, and 2.27× at 27B. At 27B, decode rises from 32.79 to 50.1 tok/s.

Stock Q4_K_M → rotated INT4 fast · local pp512 / tg128 · no MTP or speculative decoding
ModelPrefill stock → this workDecode stock → this workSpeedup prefill / decode
Qwen3.5-4B5,477 → 11,012145.2 → 200.62.01× / 1.38×
Qwen3.5-9B3,005 → 6,62495.9 → 126.22.20× / 1.32×
Qwen3.8-27B NEW888 → 2,01332.79 → 50.12.27× / 1.53×

All throughput is in tokens/s. The stock 27B baseline is reported in §2; the detailed §7 table compares the two INT4 presets. The 50.1 tok/s figure is the best recorded selected decode build. Fast’s perplexity change vs BF16 is +8.67% / +4.50% / +4.55% at 4B / 9B / 27B. The quality preset at 27B gives 1,218 tok/s prefill, the same 50.1 tok/s decode, and +1.27% perplexity. Full measurements: §2, §5–7 and Table 10.

4B / 9B / 27B — PUBLISHED GPU COMPARISONS

27B at the
bandwidth limit.

At 27B, the RX 7900 XT records 50.1 tok/s decode vs the RTX 4090’s published 49.8, while delivering 2,013 tok/s prefill vs the RTX 5080’s 1,673. No MTP or speculative decoding in the report’s local results.

Qwen3.8-27B · tokens per second · higher is better
GPUPrefill tok/sDecode tok/s
RTX 5090 Published · CUDA IQ4_XS3,21381.8
RTX 4090 Published · CUDA IQ4_XS2,51049.8
RX 7900 XT THIS WORKRotated INT4 · fast2,01350.1
RTX 5080 Published · CUDA IQ4_XS1,67349.4
RTX 5070 Ti Published · CUDA IQ4_XS1,27642.1
RTX 5070 No 27B figure in the report——
RTX 3090 Published · CUDA IQ4_XS1,04243.0
RTX 5060 Ti 16 GB Published · CUDA IQ4_XS81527.6

November 3 report, §2 / Table 1: local RX 7900 XT pp512 / tg128 results and the report’s cited NVIDIA figures. NVIDIA source: Local LLM Advisor. NVIDIA uses Q4 at 4B/9B and IQ4_XS at 27B; these are cross-source comparisons with different quantization, kernels, and benchmark conditions.

27B: 50.1 tok/s is the best recorded selected decode build. Fast: +4.55% perplexity and 0.0565 KLD vs BF16; quality: +1.27% and 0.0184. Peak VRAM: 15,853 MiB (fast). The 0.3 tok/s numerical lead over the published 4090 result is small; the major gain is 1.53× the stock card’s decode.

What the results establish

The default quality preset reaches 7,140 tok/s prefill and 200.7 tok/s decode: 1.30× and 1.38× Q4_K_M throughput at comparable measured perplexity degradation (+1.92% vs +2.00%). The fast preset reaches 11,012 tok/s prefill at +8.67% perplexity degradation. The same pipeline is demonstrated on Qwen3.5-4B, the Ossicle-4B fine-tune, Qwen3.5-9B, and Qwen3.8-27B. RDNA3 gfx1100 is the tested GPU target. Decode varies by about ±1.5 tok/s with temperature. Cross-GPU leaderboard figures in the report use different conditions and are contextual comparisons.

02 / MODEL ARCHITECTUREAUDIO + LANGUAGE · 2026
OSSICLE-4B

Giving a language
model an ear.

A 4.9B audio-language model built by grafting Qwen3-Omni’s audio encoder onto Qwen3.5-4B.

A frozen audio encoder, a trained projector, and LoRA adapters connect speech, sound, and music to the language model. Released with evaluation code, quantized checkpoints, and streaming support for long recordings.

AUDIO
Qwen3-Omni encoderFrozen · 0.65B parameters
Trained projectorAudio features → language space
Qwen3.5-4B + LoRAText answers about what it hears
57.0%

MMAU-Pro
Two-pass system

Ossicle describes the clip, then base Qwen3.5-4B answers from that text and Ossicle’s answer. Single-pass score: 52.0%. Category prompts and sampling settings were selected on MMAU-Pro; see the evaluation notes.

OSSICLE-4B / BENCHMARK COMPARISONS

A 4B backbone.
Ahead of established audio models.

57.0% on MMAU-Pro: +2.1 percentage points over the locally reproduced MOSS-Audio-4B-Instruct, and above the cited Kimi-Audio-7B and Qwen2.5-Omni-7B results.

MMAU-Pro Overall score (%) · higher is better
Model / evaluationScore
MOSS-Audio-4B-Instruct Author-reported58.16
Ossicle-4B THIS WORKTwo-pass system · measured57.0
Kimi-Audio-7B Published comparison56.6
MOSS-Audio-4B-Instruct Locally reproduced · its own prompting54.9
Qwen2.5-Omni-7B Published comparison52.2

+2.1 pp over MOSS in the local reproduction. A higher reported Pro score than the cited 7B Kimi and Qwen results.

MMAU test-mini Release comparison (%) · higher is better
Model / evaluationScore
MOSS-Audio-4B-Instruct Published comparison in Ossicle release75.8
Kimi-Audio-7B Published comparison in Ossicle release72.4
Ossicle-4B · INT4 GPTQ THIS WORKvLLM · measured71.9
Ossicle-4B · BF16 Single-pass · measured71.8
Qwen2.5-Omni-7B Published comparison in Ossicle release65.6

+6.2 pp over the cited Qwen score in BF16. INT4 GPTQ preserves the measured score: 71.9% vs 71.8% BF16.

Sources: Ossicle release results and evaluation notes; INT4 results; MOSS author-reported comparison. External model figures follow the cited release comparison; evaluation setups and dataset versions can differ.

How to read the wins

MMAU-Pro: Ossicle’s exact two-pass score is 56.97%, rounded to 57.0%; the single-pass model scores 52.0%. The second pass uses base Qwen3.5-4B; category-specific prompting and speech/voice-chat sampling were selected on MMAU-Pro. MOSS’s 54.9% is a local reproduction using its own prompting and the same Pro scorer; its authors report 58.16% separately. Kimi and Qwen are published comparison figures, not local reruns. On test-mini, the released BF16 model scores 71.8%, and the INT4 GPTQ checkpoint scores 71.9%; a 0.1-point difference is within sampling noise. The mini table retains the external scores cited by the Ossicle release rather than mixing in scores from other evaluation versions.

03 / SELECTED RESEARCH & BUILDSTHE THREAD: DO MORE WITH LESS

Other ways of
working around a limit.

01
RETRIEVAL · TECHNICAL REPORT · 2026

Atlas V14

Retrieve a conversation by its strongest matching turn. Turn-level scoring lifts the same encoder from 406 to 436 all-gold passes out of 470 LongMemEval-S questions under the released evaluator; a direct annotated-ID check gives 433/470.

Read report ↗
02
NEURAL PROGRAMS · PAPER · 2026

Portable Neural Programs

Tests whether unchanged learned artifacts can work across language-model hosts, then examines compiling acquired behavior into native model weights.

Read paper ↗
03
LOCAL AI · PAPER · 2026

DRiPP

How should two local language models pass information on a 16 GB GPU? A comparison of six message formats finds concise prose summaries balance factual fidelity with token and memory cost.

Read paper ↗
EMBEDDED SYSTEMS · IEEE GESSC 2023

Preserve

Low-cost sensors and predictive models for agricultural emissions management on small and medium farms. Co-authored at Castleknock College and published at IEEE GESSC.

Read publication ↗
ASSISTIVE HARDWARE · IRISH PATENT IES87168

Skip-A-Slip

A guide stick that detects wet surfaces and warns visually impaired users through audio. Built around a single NE555 timer circuit with nearly no added cost or weight.

Built 2018–19 · Patented 2020
SEMANTIC SEARCH · 2023

IdeaGenie

A free competitor-discovery tool trained on more than one million companies from Crunchbase, Product Hunt, YC, and Kickstarter.

Full-stack engineering · Machine learning
04 / BACKGROUNDENGINEERING + ENTREPRENEURSHIP

Across the stack.
And disciplines.

EECS + Business at UC Berkeley, through the Management, Entrepreneurship, & Technology program.

From a timer circuit in a guide stick to GPU instructions for a language model, I’m interested in finding the smallest system that solves the problem well.

RECOGNITION

Irish patent IES87168 · IEEE GESSC publication · SciFest National Finals, Excellence in STEM (2023)

stEP Business Incubator

2024
Berkeley Haas

Validated a B2B agricultural-emissions platform and designed a marketplace connecting farmers with sustainable buyers.

Patch Accelerator Fellow

2023
Dogpatch Labs · Ireland

One of approximately 30 fellows in a youth accelerator backed by Stripe and NDRC, with mentorship from Intercom and Stripe founders.

Process Engineering Intern

2023
Intel · FAB-24, Leixlip

Worked in Back-End Metals at the 14 nm fab: physical vapor deposition, metal etch, and statistical process control.

05 / OFF THE CLOCK

Also making
some noise.

I release music as SVT. Another place to experiment with structure, texture, and sound.

Listen on Spotify ↗
LET’S BUILD SOMETHING

Have an interesting constraint?

sachinmahesh@berkeley.edu ↗