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Jimin Ha

PROFILE

Jimin Ha

Jimin Ha developed and optimized advanced attention mechanisms and multimodal model features across the vllm-project/vllm-gaudi and HabanaAI/vllm-fork repositories. He engineered interleaved sliding window attention and FusedSDPA kernels to improve long-context processing, memory efficiency, and throughput for models like Gemma3 and Qwen3-VL. Using Python, PyTorch, and CUDA, Jimin refactored attention paths, introduced memory-aware design for vision models, and enforced robust initialization sequences to ensure reliable deployment. His work addressed both feature enablement and stability, including fixes for dynamic shape handling and profiling regressions, resulting in scalable, production-ready model deployments with measurable improvements in runtime efficiency and maintainability.

Overall Statistics

Feature vs Bugs

67%Features

Repository Contributions

12Total
Bugs
3
Commits
12
Features
6
Lines of code
1,890
Activity Months6

Work History

February 2026

1 Commits • 1 Features

Feb 1, 2026

February 2026 monthly summary: Delivered a focused feature upgrade in vllm-gaudi by switching Qwen3-VL attention from HPUAttention to HPUMMEncoderAttention, refactoring the attention path for better sequence processing, efficiency, and scalability in multimodal applications. No major bugs fixed this month; efforts centered on robust delivery, code quality, and clear ownership to support subsequent performance optimization and deployment.

December 2025

1 Commits

Dec 1, 2025

December 2025: Gemma3 Multimodal Model Stability and Compatibility Fix for vLLM Gaudi. Delivered a targeted fix to Gemma3 compilation errors in multimodal inputs by replacing dynamic shapes with fixed shapes, aligning with upstream changes, and re-enabling tests to restore multimodal processing stability. Also removed the merge_multimodal workaround and text embedding dynamic paths now that the masked_scatter issue is fixed, resulting in a cleaner, more maintainable code path. Commits include 36d92db13b80c3d767821d11e0eff936eebf59d1 with signed-off attribution, linked to upstream discussions.

October 2025

1 Commits • 1 Features

Oct 1, 2025

Month 2025-10 — Focused on performance and memory optimization for Gemma3 multimodal deployment within vllm-gaudi, delivering substantial improvements in runtime efficiency and memory footprint to enable longer context and scalable inference in production. Key features delivered: - Gemma3 Multimodal Performance and Memory Optimization: introduced bucketing for the vision tower to reduce recompilation overhead, enhanced multimodal merging via torch.where, memory optimizations to support longer sequences, and ensured proper plugin initialization order for reliable startup. - Port and integration work: ported PT_HPU_SDPA_QKV_SLICE_MODE_FWD from vllm-fork to further reduce memory use for longer sequences and improve stability. - Initialization discipline: established 01/02 prefixes for the general plugin initialization order to guarantee ops run before the model, improving startup determinism. Major bugs fixed: - None reported for this repo in Oct 2025; this month’s work focused on performance/memory optimization and initialization correctness rather than bug fixes. Overall impact and accomplishments: - Achieved measurable improvements in memory efficiency and reduced recompilation overhead for Gemma3 multimodal workloads, enabling longer sequences and more scalable deployments with predictable startup behavior. - Strengthened code quality and maintainability through explicit initialization ordering and ported features from a fork with alignment to in-tree practices. Technologies/skills demonstrated: - PyTorch-based model optimization, tensor operations (torch.where), and memory-aware design. - Multimodal systems engineering, repository maintenance, and porting features across forks. - Code hygiene: explicit plugin initialization sequencing and signed-off commits. Commit context: - Repository: vllm-project/vllm-gaudi - Commit: 611f4155ec3e79d4682d58683a841ec88d56522d - Message: Gemma3 Multimodal optimization (#404) with detailed changes and credits. - Sign-offs: Jimin Ha, Mohit Deopujari; Co-authored by Mohit Deopujari.

September 2025

3 Commits • 2 Features

Sep 1, 2025

September 2025 performance summary for vllm-gaudi (Gemma3 and vision model optimizations). Delivered key features and stability improvements enabling Gemma3 enablement and more memory-efficient vision processing, with tangible CI reliability gains and a clear path to further scale. Key features delivered: - Gemma3 Model Improvements and Testing: Added interleaved sliding window support for longer prompts in Gemma3 (V1 enablement) and enhancements to multimodal testing. Included updates to tests and configuration for the gemma-3-4b model to fix test script naming and add necessary config. Commits 481b163a5ae23edb7939521f7dbff34deea0a6a3 and a0bbe78f442d5c5e26b383e83b944619d63a5c08. - Vision Model Memory and Performance Optimization: Implemented HPUMultiHeadAttention with FusedSDPA to improve memory efficiency and speed in vision models. Commit d6611751fa4df6c598e32daf1c0645c42813f279. Major bugs fixed: - Stabilized Gemma3-4b IT test workflow by correcting model file naming and test script paths (gemma-3-4b-it) to ensure reliable CI runs. Commits a0bbe78f442d5c5e26b383e83b944619d63a5c08 and related changes. Overall impact and accomplishments: - Brought Gemma3 closer to production readiness with interleaved sliding window, test, and config polish, while stabilizing CI for gemma-3-4b-it. Achieved notable memory and performance improvements in vision models via FusedSDPA, enabling more efficient multi-image processing and larger prompts. These efforts reduce runtime risk, shorten iteration cycles, and accelerate progress toward larger Gemma3 deployments. Technologies/skills demonstrated: - PyTorch-based model optimization (HPUMultiHeadAttention, FusedSDPA), memory profiling and optimization, test automation and CI stability, model configuration management, and cross-team collaboration to port features from v0 to v1 Gemma3 implementations.

August 2025

1 Commits

Aug 1, 2025

Monthly work summary for 2025-08 focusing on HabanaAI/vllm-fork. Delivered a focused bug fix to max_batch_size initialization for Llama profile runs, which ensures the value is set to 1 only for multimodal models (mrope or mm_optimized). This corrected a profiling-related performance degradation and restored expected throughput for Llama v3.1 70B deployments. The change improves stability under load and reduces risk of regressions in high-traffic inference scenarios.

July 2025

5 Commits • 2 Features

Jul 1, 2025

July 2025 summary focusing on long-context processing, performance, and stability across HabanaAI forks.

Activity

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Quality Metrics

Correctness86.6%
Maintainability80.0%
Architecture85.0%
Performance83.4%
AI Usage28.4%

Skills & Technologies

Programming Languages

C++PythonShellYAML

Technical Skills

Attention MechanismsBackend DevelopmentCI/CDCUDADeep LearningGPU ProgrammingGPU programmingHPU AccelerationHPU Extension DevelopmentHPU OptimizationKernel OptimizationLLM InferenceLLM IntegrationLLM OptimizationMachine Learning

Repositories Contributed To

3 repos

Overview of all repositories you've contributed to across your timeline

vllm-project/vllm-gaudi

Sep 2025 Feb 2026
4 Months active

Languages Used

PythonShellYAML

Technical Skills

Attention MechanismsCI/CDGPU programmingLLM OptimizationModel IntegrationPerformance Tuning

HabanaAI/vllm-fork

Jul 2025 Aug 2025
2 Months active

Languages Used

C++PythonYAML

Technical Skills

Attention MechanismsDeep LearningHPU AccelerationHPU OptimizationKernel OptimizationLLM Inference

HabanaAI/vllm-hpu-extension

Jul 2025 Jul 2025
1 Month active

Languages Used

Python

Technical Skills

Attention MechanismsBackend DevelopmentCUDADeep LearningGPU ProgrammingHPU Extension Development