Victim Cache Read-Modify-Write Handling for Lower Write Latency
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Solution Overview
Problem
Existing computing systems face significant latency issues due to the time required to access data from main memory, which can be mitigated by incorporating a victim cache to reduce cache miss rates and improve efficiency.
Innovation Solution
Incorporating a victim cache that stores data recently evicted from the main cache, allowing it to service cache misses directly without waiting for the main cache to determine the memory address, thereby reducing latency and increasing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is stored in main memory, then data capacity is sufficient, but access latency is significant
Solution Approach 1:
The memory system is segmented into multiple cache levels (L1, L2, victim cache) with different capacities and access speeds. The L1 cache provides fast access for frequently used data, while the victim cache captures evicted data that may be reused soon, creating a hierarchical structure that balances capacity and latency.
Solution Approach 2:
The victim cache is nested within the L1 cache structure, acting as an extension that captures evicted data. When L1 evicts data, it first checks the victim cache before proceeding to L2, creating a nested lookup hierarchy that reduces latency for recently evicted data without requiring access to slower L2 or main memory.
2Loss of time
If a standard cache is used, then cache latency is reduced, but conflict misses increase
Solution Approach 1:
The victim cache acts as an intermediary between the L1 cache and L2 cache. It captures data evicted from L1 and serves as a buffer that can satisfy subsequent accesses to this data, reducing conflict misses by providing an additional lookup opportunity before accessing L2.
Solution Approach 2:
Instead of permanently discarding data when it is evicted from L1, the victim cache recovers and temporarily stores this data. This allows the system to recover from conflict misses by retrieving data from the victim cache if it was evicted recently and is still needed.
3Productivity
If victim cache is added to reduce conflict misses, then cache efficiency improves, but device complexity increases
Solution Approach 1:
The victim cache is merged with the L1 cache structure, sharing control logic and tag comparison resources. The victim cache uses the same tag array and control unit as L1, eliminating the need for separate control logic and reducing overall complexity despite adding storage capacity.
Solution Approach 2:
The L1 cache control logic serves multiple functions: it manages both the primary L1 cache and the victim cache, handling tag comparisons, data retrieval, and eviction decisions for both structures. This multi-functionality reduces the need for duplicate control units and simplifies the overall architecture.
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture are disclosed to facilitate read-modify-write support in a victim cache. An example apparatus includes a first storage coupled to a controller, a second storage coupled to the controller and parallel coupled to the first storage, and a storage queue coupled to the first storage, the second storage, and to the controller, the storage queue to obtain a memory operation from the controller indicating an address and a first set of data, obtain a second set of data associated with the address from at least one of the first storage and the second storage, merge the first set of data and the second set of data to produce a third set of data, and provide the third set of data for writing to at least one of the first storage and the second storage.