CPU Northbridge Read Buffer for GPU Memory Access
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Solution Overview
Problem
Conventional computing systems experience slow CPU reads from GPU local memory due to uncached, serialized data access, which limits performance.
Innovation Solution
Implementing a read combining mechanism with read buffers in the CPU northbridge to enable efficient data retrieval from GPU local memory, allowing multiple uncached reads and peer-to-peer reads, and using shared buffers for both writes and reads to improve access speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If uncached reads are performed from GPU local memory to CPU, then data access simplicity is maintained, but read speed is slow due to serialized access
Solution Approach 1:
A buffer is introduced as an intermediary component between the GPU local memory and CPU. The buffer stores data from GPU memory regions, allowing the CPU to retrieve data faster by accessing the buffer rather than performing slow uncached reads directly from GPU memory. This mediator resolves the speed limitation while maintaining relative simplicity in the access mechanism.
Solution Approach 2:
Data is pre-loaded into the buffer from the GPU local memory before the CPU needs it. By performing the data transfer in advance (preliminary action), the CPU can subsequently access data from the buffer at high speed without waiting for slow uncached reads during actual processing.
2Loss of time
If data is read from GPU local memory using conventional uncached methods, then implementation simplicity is maintained, but access time is excessive
Solution Approach 1:
The buffer serves as a time-saving intermediary that stores frequently accessed GPU memory data. By managing this buffer, the system reduces data access time significantly, as the CPU can retrieve data from the buffer much faster than performing uncached reads from GPU local memory, despite the added complexity of buffer management.
3Productivity
If read buffers are implemented in the CPU northbridge, then read performance is dramatically improved, but system complexity increases
Solution Approach 1:
The read buffers in the CPU northbridge are designed to serve multiple purposes: they handle reads from GPU local memory, support peer-to-peer reads between GPUs, and can be shared between different processing units. This multi-functionality justifies the increased complexity by providing broad productivity improvements across various operations.
Solution Approach 2:
Rather than implementing full cache complexity, the patent uses partial caching through read buffers that store entire memory regions (e.g., 64-byte lines). This excessive action of loading complete regions provides sufficient productivity improvement without implementing the full complexity of traditional cache systems.
Data Source
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AI summary
Disclosed herein are systems, apparatuses, and methods for enabling efficient reads to a local memory of a processing unit. In an embodiment, a processing unit includes an interface and a buffer. The interface is configured to (i) send a request for a portion of data in a region of a local memory of an other processing unit and (ii) receive, responsive to the request, all the data from the region. The buffer is configured to store the data from the region of the local memory of the other processing unit.