GPU Huffman Decoding with Overlapped Chunk Boundary Correction
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Solution Overview
Problem
Existing Huffman decoding schemes are not suitable for parallel processing due to the unpredictable relationship between encoded and decoded bits, which prevents the implementation of efficient parallel decoding methods.
Innovation Solution
The system partitions the Huffman encoded bitstream into chunks and assigns each execution unit to decode a chunk and an extra portion of an adjacent chunk, allowing for parallel decoding while correcting incorrectly decoded data at chunk boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a naive parallel algorithm is used to decode Huffman data, then parallel processing capability is improved, but decoding correctness deteriorates due to unpredictable relationship between encoded and decoded bits
Solution Approach 1:
The patent divides the encoded bitstream into multiple fixed-size chunks, with each execution unit assigned to decode a specific chunk. This segmentation allows parallel processing while managing the unpredictable bit relationship by isolating decoding tasks into manageable segments with controlled overlap regions.
Solution Approach 2:
Each execution unit decodes an extra portion of the adjacent chunk beyond its assigned chunk boundary before final validation. This preliminary action ensures that potentially incorrect decodings at chunk boundaries are generated in advance, allowing subsequent validation and correction steps to identify and fix errors systematically.
Solution Approach 3:
The patent implements a validation mechanism where decoded data at chunk boundaries is checked for correctness. When incorrect decodings are detected in the extra portion, the system uses feedback from adjacent execution units to identify the correct symbol boundaries and correct the errors, ensuring decoding reliability.
2Productivity
If parallel decoding is implemented by assigning fixed chunks to execution units, then processing efficiency is improved, but decoding accuracy deteriorates at chunk boundaries due to misalignment with symbol boundaries
Solution Approach 1:
The patent applies different processing strategies to different regions of the chunk. The majority of each chunk is decoded with standard parallel processing, while the extra portion at the boundary receives special attention with validation and correction mechanisms. This local quality approach maintains high overall efficiency while ensuring accuracy at critical boundary regions.
Solution Approach 2:
Each execution unit performs partial decoding of the adjacent chunk (the extra portion) beyond its strict assignment boundaries. This excessive action of decoding additional data ensures that symbol boundaries are not missed, and the validation process can identify and correct any misalignments, sacrificing some redundant computation for guaranteed accuracy.
3Productivity
If execution units decode only their assigned chunk without overlapping, then resource utilization is improved, but decoding completeness deteriorates due to missed symbol boundaries
Solution Approach 1:
Execution units perform preliminary decoding of the extra portion of adjacent chunks before the actual chunk boundaries are finalized. This preliminary action ensures that no symbol boundaries are missed, as the extra portion acts as a buffer zone that captures potential boundary locations, preventing information loss.
Solution Approach 2:
The validation process uses feedback from comparing decoded results across chunk boundaries to identify the correct symbol boundaries. When execution units decode extra portions, the system validates these results and uses feedback to determine where actual symbol boundaries lie, ensuring complete and accurate decoding without permanent information loss.
Data Source
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AI summary
Systems, apparatuses, and methods for implementing a parallel Huffman decoding scheme are disclosed herein. A system with a plurality of execution units receives a Huffman encoded bitstream. The system partitions the encoded bitstream into a plurality of chunks. Each execution unit is assigned to decode a separate chunk of the encoded bitstream as well as an extra portion of an adjacent chunk. With this approach, the decoding of the bitstream overlaps for a programmable amount of data at each chunk boundary since each execution unit, excluding the first execution unit decoding the first chunk of the bitstream, will likely decode a certain number of symbols incorrectly at the beginning of the chunk since the chunk boundaries will not be aligned with symbol boundaries. The system determines, from the decoded extra portion at each chunk boundary, where incorrectly decoded ends and where correctly decoded data begins for each decoded chunk.