Pipelined Binary Search Quantization for Low-Memory Neural Inference
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Solution Overview
Problem
Neural networks require significant computational and memory resources for floating-point arithmetic in quantized activations, leading to exponential memory storage costs for threshold values, especially with non-linear activations like tanh and sigmoid.
Innovation Solution
Implement a binary search tree traversal for quantization logic to compare inputs to thresholds, allowing for on-the-fly calculation of non-linear thresholds, reducing memory storage needs by using a logarithmic number of steps instead of sequential comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-thresholding operations are used for quantized activations, then accuracy is preserved, but memory storage cost for threshold values grows exponentially with bit-width
Solution Approach 1:
The patent segments the threshold values into multiple levels organized as a binary search tree structure. Instead of storing all threshold values in a flat exponential array, the thresholds are divided into hierarchical levels where each level contains a subset of thresholds. This segmentation reduces the memory storage requirement from exponential to linear with respect to bit-width, while maintaining the ability to perform accurate multi-thresholding operations through the tree traversal mechanism.
2Quantity of substance
If sequential comparisons are used for binary search, then memory storage is reduced, but computational time increases
Solution Approach 1:
The patent implements a dynamic pipelined binary search mechanism where multiple comparison operations are performed concurrently across different pipeline stages. Instead of waiting for sequential comparisons to complete, the system dynamically progresses through multiple comparison stages in parallel, with each stage processing a different portion of the search space. This dynamic approach maintains reduced memory storage while significantly decreasing computational time through concurrent operations.
3Measurement precision
If wider bit width quantizations are implemented, then accuracy is improved, but latency increases for neural network inference
Solution Approach 1:
The patent performs preliminary organization of threshold values into a binary search tree structure during system initialization or model loading. This preliminary action pre-computes and stores the hierarchical threshold arrangement, enabling subsequent inference operations to efficiently traverse the pre-organized structure. By performing this organizational work in advance, the system enables faster inference latency for wider bit-width quantizations without sacrificing accuracy, as the traversal of pre-organized thresholds is more efficient than on-the-fly computation.
Data Source
AI summary
Embodiments herein describe techniques for spatially unrolling thresholds (e.g., steps) for traversing a binary search tree. A binary search tree permits quantization logic to quickly search through thresholds stored in memory to perform quantization (e.g., convert an input value into one of the thresholds). Assuming the thresholds are sorted in order when stored in memory, the result of comparing the input value to a threshold in the current level of the binary tree can be used to select the address of the next threshold in the next level of the binary tree. This permits the quantization logic to traverse the thresholds in a logarithmic manner.


