[ET-VK] linear_qta8a_qga4w graph pass#13000
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Pull Request resolved: #12574 # Changes * Introduce `linear_qta8a_qga4w` custom operator in `custom_ops_lib.py` to handle dynamic activation + grouped weight quantized linear operations * Add pattern matching and fusion logic in `FuseQuantizedOpsTransform` to detect and replace dequant + dequant + linear sequences with the new fused operator * Implement comprehensive test coverage in `test_vulkan_passes.py` for the QTA8A_QGA4W fusion pattern validation * Add 4-bit weight packing utilities and grouped quantization support for efficient memory usage # Motivation The existing quantization workflow in Vulkan backend processes dynamic activation + grouped weight quantized linear operations as separate quantize/dequantize/linear steps, which creates performance overhead through: * Multiple kernel dispatches instead of a single fused operation * Intermediate tensor allocations for dequantized weights and activations * Suboptimal memory bandwidth utilization The new `linear_qta8a_qga4w` operator fuses the entire sequence into a single operation that: * Directly processes 8-bit quantized activations with per-token scales/zero-points * Handles 4-bit grouped quantized weights with configurable group sizes * Eliminates intermediate dequantization steps by performing dequantization inline * Reduces memory footprint through packed 4-bit weight storage This aligns with the broader goal of optimizing quantized model inference in the Vulkan backend by leveraging graph-level transformations to improve computational efficiency while maintaining numerical accuracy. ghstack-source-id: 299473616 @exported-using-ghexport Differential Revision: [D78291269](https://our.internmc.facebook.com/intern/diff/D78291269/)
🔗 Helpful Links🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/13000
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…up (#13001) This PR was created by the merge bot to help merge the original PR into the main branch. ghstack PR number: #12575 by @ahmtox ^ Please use this as the source of truth for the PR details, comments, and reviews ghstack PR base: https://github.com/pytorch/executorch/tree/gh/ahmtox/43/base ghstack PR head: https://github.com/pytorch/executorch/tree/gh/ahmtox/43/head Merge bot PR base: https://github.com/pytorch/executorch/tree/gh/ahmtox/42/orig Merge bot PR head: https://github.com/pytorch/executorch/tree/gh/ahmtox/43/orig @diff-train-skip-merge cc @SS-JIA @manuelcandales @cbilgin --------- Co-authored-by: morelos <morelos@devvm4573.ash0.facebook.com> Co-authored-by: ahmtox <69552192+ahmtox@users.noreply.github.com>
Gasoonjia
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Jul 30, 2025
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This PR was created by the merge bot to help merge the original PR into the main branch.
ghstack PR number: #12574 by @ahmtox
^ Please use this as the source of truth for the PR details, comments, and reviews
ghstack PR base: https://github.com/pytorch/executorch/tree/gh/ahmtox/42/base
ghstack PR head: https://github.com/pytorch/executorch/tree/gh/ahmtox/42/head
Merge bot PR base: https://github.com/pytorch/executorch/tree/gh/ahmtox/41/orig
Merge bot PR head: https://github.com/pytorch/executorch/tree/gh/ahmtox/42/orig
@diff-train-skip-merge