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.

Qwen3.5-4B on the RX 7900 XT

A complete rotated GPTQ-INT4 inference path in llama.cpp: native INT4 matrix instructions, custom attention and gated-delta-net kernels, and a decode graph cut from 847 to 236 launches per token.

11,012 tok/s

Prefill · pp512 · fast preset

200.6 tok/s

Decode · tg128 · empty context

2.01×

Prefill throughput vs Q4_K_M

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 same pipeline also transfers to Ossicle-4B’s language backbone. One copy of the weights stays in VRAM, with peak usage of 3,358 MiB for the stock model’s quality preset.

ONE GPU. ONE BUILD.RX 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.

QWEN3.5-4B / PUBLISHED GPU COMPARISON

Past the 5080’s prefill.
At its decode speed.

On the reported figures, the RX 7900 XT delivers 9.5% more prefill throughput than the RTX 5080 and 91% of the RTX 4090’s decode throughput.

Qwen3.5-4B · tokens per second · higher is better
GPUPrefill tok/sDecode tok/s
RTX 5090 Published · CUDA Q416,036313.6
RTX 4090 Published · CUDA Q414,882220.2
RX 7900 XT THIS WORKRotated INT4 · fast11,012200.6
RTX 5080 Published · CUDA Q410,057200.5

RX 7900 XT: pp512 / tg128 from the November 2 report, §2 & §5. NVIDIA: Local LLM Advisor’s Q4 leaderboard. These are cross-source results, with different kernels, quantization, and undisclosed NVIDIA prompt settings. Fast has +8.67% perplexity vs BF16. The 0.1 tok/s decode edge is within the RX run’s ±1.5 tok/s temperature variation; the supported claim is comparable decode throughput.

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. Results cover two 4B checkpoints of the same architecture on RDNA3; other model sizes and GPU families are untested. 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 ↗