Multi-Tile GPU Memory Management for Cross-Tile Page Migration
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Solution Overview
Problem
Current graphics processing units (GPUs) face challenges in optimizing cache access latency and memory management across multiple processing units, which hinders efficient parallel processing and data transfer in graphics and machine learning operations.
Innovation Solution
A unified memory address space is implemented, allowing GPUs to access physical processor and GPU memories via a common virtual memory address, enabling efficient data sharing and reducing cache access latency through a page transfer mechanism and distributed memory model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a unified memory address space is implemented across multiple GPUs, then data sharing efficiency and processing throughput are improved, but memory management complexity and cache access coordination overhead increase
Solution Approach 1:
The memory system is segmented into local memory spaces for each GPU tile and a unified virtual address space. Each GPU maintains its own physical memory and cache, while the unified address space provides a logical view that allows cross-tile access. This segmentation allows independent memory management for each GPU while enabling coordinated access through the unified interface.
Solution Approach 2:
A page transfer mechanism acts as an intermediary between different GPU memory spaces. When data needs to be accessed across tile boundaries, the page transfer mechanism facilitates the transfer and caching of data pages, managing the complexity of inter-GPU memory access while presenting a unified interface to applications.
2Speed
If cache access latency is reduced through optimized memory architecture, then processing speed is improved, but the complexity of cache coherence management across multiple tiles increases
Solution Approach 1:
Each GPU tile is equipped with its own local cache memory optimized for fast access to frequently used data. The cache hierarchy is designed so that each tile has priority access to its local cache, providing low-latency access for local operations while maintaining the ability to access remote data when necessary.
Solution Approach 2:
The page transfer mechanism serves as an intermediary for cache coherence management across tiles. It handles the coordination of data transfers between tiles, managing cache invalidation and synchronization protocols, thereby reducing the burden on individual GPUs while maintaining system-wide coherence.
3Productivity
If data is transferred between multiple GPUs through a unified memory system, then parallel processing efficiency is improved, but data transfer overhead and memory bandwidth consumption increase
Solution Approach 1:
Data is pre-loaded into local caches and page buffers before being needed by processing units. The system anticipates data access patterns and performs preliminary data transfer and caching operations, reducing the need for frequent high-speed memory accesses during actual processing and thereby reducing overall bandwidth consumption.
Solution Approach 2:
The page transfer mechanism creates copies of data pages in appropriate memory locations across different GPUs. Instead of repeatedly accessing the same data across tile boundaries, data is copied to local caches and page buffers where it can be accessed efficiently by multiple processing units, reducing the total volume of data transferred over the inter-GPU interface.
Data Source
AI summary
Multi-tile Memory Management for Detecting Cross Tile Access, Providing Multi-Tile Inference Scaling with multicasting of data via copy operation, and Providing Page Migration are disclosed herein. In one embodiment, a graphics processor for a multi-tile architecture includes a first graphics processing unit (GPU) having a memory and a memory controller, a second graphics processing unit (GPU) having a memory and a cross-GPU fabric to communicatively couple the first and second GPUs. The memory controller is configured to determine whether frequent cross tile memory accesses occur from the first GPU to the memory of the second GPU in the multi-GPU configuration and to send a message to initiate a data transfer mechanism when frequent cross tile memory accesses occur from the first GPU to the memory of the second GPU.