Peripheral Memory Read Prefetch via System Cache Interconnect
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Solution Overview
Problem
Existing data processing systems face challenges in efficiently handling memory read requests due to the need to ensure memory hazards are avoided, which can lead to increased latency and complexity in managing memory access requests.
Innovation Solution
A data processing system is designed with an interconnect featuring a system cache, a peripheral component with a request ordering queue, and a memory. The peripheral component queues memory access requests in receipt order, delays memory read requests until completion responses for preceding write requests are received, and issues memory read prefetch requests to cache data in the system cache.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If memory read requests are issued immediately without waiting for write completions, then read latency is reduced, but memory hazards may occur
Solution Approach 1:
The system performs preliminary actions by issuing memory read prefetch requests to the system cache before the actual memory read requests are issued to the interconnect. This allows the cache to prepare data in advance, reducing the latency of the actual read operations while maintaining proper ordering constraints.
Solution Approach 2:
The system cache acts as an intermediary between the peripheral component and the memory. By prefetching data into the cache before read requests are issued, the system reduces read latency without compromising memory hazard avoidance, as the cache handles the timing and ordering concerns.
2Reliability
If memory read requests are delayed until write completion responses are received, then memory hazards are avoided, but read latency increases
Solution Approach 1:
The system performs preliminary actions by issuing memory read prefetch requests to the system cache before the actual memory read requests are issued to the interconnect. This allows the cache to prepare data in advance, reducing the latency of the actual read operations while maintaining proper ordering constraints.
3Reliability
If complex monitoring of read and write targets is implemented, then memory hazard detection is improved, but device complexity increases
Solution Approach 1:
The system cache acts as an intermediary between the peripheral component and the memory. By prefetching data into the cache before read requests are issued, the system reduces read latency without compromising memory hazard avoidance, as the cache handles the timing and ordering concerns.
Solution Approach 2:
The system uses the existing system cache infrastructure to handle prefetching operations, allowing the cache to serve itself by automatically managing the prefetch data. This avoids the need for complex external monitoring mechanisms while still ensuring proper memory hazard avoidance.
Data Source
AI summary
Peripheral components, data processing systems and methods of operating such peripheral components and data processing systems are disclosed. The systems comprise an interconnect comprising a system cache, a peripheral component coupled to the interconnect, and a memory coupled to the interconnect. The peripheral component has a memory access request queue for queuing memory access requests in a receipt order. Memory access requests are issued to the interconnect in the receipt order. A memory read request is not issued to the interconnect until a completion response for all older memory write requests has been received from the interconnect. The peripheral component is responsive to receipt of a memory read request to issue a memory read prefetch request comprising a physical address to the interconnect and the interconnect is responsive to the memory read prefetch request to cause data associated with the physical address in the memory to be cached in the system cache.