Overflow Region Memory Management via Credit Unit Recycling
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Solution Overview
Problem
Deduplicated memory systems face issues such as hash collisions and end-of-memory capacity, leading to invalid entries in overflow memory regions, which can result in memory holes if not properly managed.
Innovation Solution
A deduplicated memory module with a deduplication engine, a hash table, an overflow memory region, and a credit unit, where the credit unit stores addresses of invalidated entries and manages them to prevent memory holes, and control logic generates warnings for status indications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If user data is stored in the overflow memory region when hash collision occurs or hash table is full, then the memory capacity is fully utilized, but invalid entries (memory holes) are created in the overflow region
Solution Approach 1:
The patent implements a credit unit that tracks and recovers invalid entries in the overflow memory region. When an entry is invalidated (creating a memory hole), its address is stored in the credit unit. Subsequently, when new data needs to be stored, the system checks the credit unit and reuses these recovered addresses, thereby eliminating memory holes and improving overflow region utilization without compromising data integrity.
2Quantity of substance
If the overflow memory region is used to store user data, then the virtual memory capacity is extended, but the management complexity of invalid entries increases
Solution Approach 1:
The credit unit automatically manages invalid entry addresses without requiring external intervention. When an overflow entry is invalidated, the system self-service by storing the address in the credit unit. The control logic continuously monitors and reuses these credits, reducing the management burden and simplifying the overall system operation while maintaining extended virtual memory capacity.
3Productivity
If new user data is written to a location pointed to by an overflow region entry, then the hash table is updated, but the overflow entry becomes invalid creating a memory hole
Solution Approach 1:
The system performs preliminary action by pre-tracking invalid entry addresses in the credit unit before they are needed again. When data is written that invalidates an overflow entry, the address is immediately recorded in the credit unit. This preliminary tracking enables rapid reuse of the space without requiring complex search or allocation procedures, thus maintaining write efficiency while preventing space waste.
Data Source
AI summary
A memory module includes a host interface configured to provide an interface to a host computer; one or more memory devices; a deduplication engine configured to provide a virtual memory capacity of the memory module that is larger than a physical size of the one or more memory devices; a memory controller for controlling access to the one or more memory devices; a volatile memory comprising a hash table, an overflow memory region, and a credit unit, wherein the overflow memory region stores user data when a hash collision occurs or the hash table is full, and wherein the credit unit stores an address of an invalidated entry in the overflow memory region; and a control logic is configured to control the overflow memory region and the credit unit and generate a warning indicating a status of the overflow memory region and the credit unit.