Variable Chunk Size Memory Compression for Lower Read Latency
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Solution Overview
Problem
Current memory compression techniques suffer from significant performance overhead due to the need for decompression, limiting their use to latency-insensitive data, thereby restricting memory capacity gains and increasing total cost of ownership.
Innovation Solution
Implementing variable chunk size memory compression schemes that dynamically adjust chunk sizes based on data access patterns, allowing for low decompression latency for sparsely accessed data and high compression ratio for densely accessed data, using a new address space and translation table to enable transparent decompression without page faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory compression is applied to reduce memory cost and increase capacity, then memory capacity utilization is improved, but memory access latency increases due to decompression requirements
Solution Approach 1:
The patent divides compressed memory into multiple chunks with different compression ratios. Frequently accessed data is stored in smaller chunks with lower compression ratios for faster decompression, while less frequently accessed data is stored in larger chunks with higher compression ratios to maximize capacity utilization.
Solution Approach 2:
The patent dynamically adjusts chunk sizes and compression ratios based on access patterns. The system monitors data access frequency and automatically reorganizes compressed memory chunks, moving frequently accessed data to smaller chunks and less frequently accessed data to larger chunks, optimizing the balance between capacity and access speed.
2Productivity
If only latency-insensitive data is compressed to limit performance impact, then memory access performance is preserved, but the compressed fraction of memory footprint is limited
Solution Approach 1:
The patent applies different compression qualities to different regions of memory based on local access characteristics. Each memory chunk can have its own compression ratio optimized for its specific access pattern, allowing high-performance regions to maintain low compression while capacity-critical regions use high compression.
Solution Approach 2:
The patent changes the compression ratio parameter dynamically based on access patterns. By monitoring access frequency and adjusting compression parameters in real-time, the system can expand the compressed fraction of memory footprint when performance requirements are met and reduce compression when access patterns change.
3Quantity of substance
If variable chunk sizes are used to optimize compression ratio and access latency, then both capacity utilization and performance are improved, but system complexity increases
Solution Approach 1:
The patent implements self-service mechanisms where the compression system automatically monitors its own performance, detects access patterns, and reorganizes chunks without external intervention. The system self-adjusts compression parameters based on observed behavior, reducing the need for complex external control mechanisms.
Solution Approach 2:
The patent incorporates feedback loops that monitor memory access patterns and use this information to dynamically adjust chunk sizes and compression ratios. The system continuously receives feedback from access patterns and automatically optimizes its structure, managing complexity through adaptive control rather than static configuration.
Data Source
AI summary
Methods and apparatus for variable chunk size memory compression. A physical address space for system memory is partitioned into an uncompressed partition in which data are stored without compression and a compressed partition in which compressed data are stored using a plurality of chunk sizes. In response to a memory Read request, when it is determined that the requested data are stored in a compressed partition, the location of a compressed chunk on a memory device containing the data is determined, the data are retrieved and decompressed, and the decompressed data are returned to the core issuing the memory Read request. A compressed page table (CPT) is maintained containing entries having fields encoding a chunk size, a device address corresponding to a start of the compressed page, and one or more fields denoting sizes of each chunk in the compressed page.