Cache Line Allocation Bypassing Main Memory Reads
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Solution Overview
Problem
Current cache memory management systems incur delays and inefficiencies due to the need to read data from main memory into cache, especially when the data is immediately rewritten, leading to wasted processing time and potential congestion in the memory interface.
Innovation Solution
The system allocates cache memory and associates it with main memory, bypassing the read from main memory and allowing initialization of cache memory to a specified pattern, thereby avoiding unnecessary data retrieval and initialization through main memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cache memory automatically reads data from main memory upon allocation, then data availability in cache is improved, but processing time is wasted when data is immediately rewritten
Solution Approach 1:
The patent changes the parameter of cache allocation behavior by introducing a bypass mechanism that allows cache lines to be allocated without reading from main memory. The cache controller modifies the standard allocation process to enable direct allocation where the cache line is assigned to a memory address without performing the usual read operation, thereby eliminating unnecessary processing time when data is immediately rewritten.
Solution Approach 2:
The patent extracts the read operation from the mandatory cache allocation process. By separating the allocation function from the read function, the system can allocate cache lines without automatically reading data from main memory. This extraction allows the cache to be allocated for addresses that will be immediately rewritten, removing the time-consuming read step while maintaining cache availability.
2Device complexity
If cache controller automatically manages cache entries invisibly, then system simplicity is maintained, but software control over cache manipulation is limited
Solution Approach 1:
The patent enhances the cache controller's capabilities by making it multi-functional. The cache controller not only automatically manages cache entries but also provides software-controlled operations including direct cache line allocation, bypass reads, and manual invalidation. This universality allows the same hardware component to handle both automatic and software-directed cache manipulation, maintaining simplicity while increasing adaptability.
3Reliability
If data is read from main memory before being rewritten, then cache is populated with valid data, but data bus congestion increases and processing efficiency decreases
Solution Approach 1:
The patent implements a bypass mechanism that allows the cache allocation process to skip the read operation from main memory. When a cache line is allocated for an address that will be immediately rewritten, the system rushes through the allocation process by skipping the data read step entirely. This is achieved by allowing the cache controller to allocate cache lines directly without requiring data to be read from main memory first, thereby eliminating bus congestion and improving processing efficiency.
Data Source
AI summary
Embodiments of the current invention permit a user to allocate cache memory to main memory more efficiently. The processor or a user allocates the cache memory and associates the cache memory to the main memory location, but suppresses or bypassing reading the main memory data into the cache memory. Some embodiments of the present invention permit the user to specify how many cache lines are allocated at a given time. Further, embodiments of the present invention may initialize the cache memory to a specified pattern. The cache memory may be zeroed or set to some desired pattern, such as all ones. Alternatively, a user may determine the initialization pattern through the processor.