Remote Memory Page Tables for Single-Server Address Expansion
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Solution Overview
Problem
The physical address space of a single server cannot meet the requirements of the larger virtual address space due to the limited capacity of modern CPUs, which are typically 64-bit, while the physical address space of a single server ranges from a few tens of GBs to several TBs, falling short of the virtual address space's needs.
Innovation Solution
The method involves using a Field Programmable Gate Array (FPGA) connected to a remote memory array apparatus via a Remote Direct Memory Access (RDMA) network card module to create remote memory page table entries when local entries are not available, allowing access to expand the physical address space beyond the limitations of a single server.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the physical address space of a single server is used, then the system structure remains simple, but the memory capacity cannot meet the requirements of the virtual address space
Solution Approach 1:
The patent divides the memory system into local memory (on the server) and remote memory (in remote memory array apparatus), allowing the system to access memory resources across multiple physical locations. This segmentation enables expansion beyond the single server's physical address space limitation while maintaining a relatively simple system architecture through standardized interfaces.
Solution Approach 2:
The patent introduces a new dimension for memory addressing by implementing a remote memory access mechanism that extends beyond the traditional single-server physical address space. Through the development of remote memory page table entries and cross-memory access protocols, the system effectively adds an external memory dimension that expands the addressable space without fundamentally changing the CPU architecture.
2Quantity of substance
If remote memory array apparatus is connected via RDMA network card module, then the physical address space is expanded, but the device complexity increases
Solution Approach 1:
The patent introduces an FPGA as an intermediary component that bridges the CPU, local memory, and remote memory access. The FPGA implements the complex address translation and memory management functions, isolating the complexity from the main system architecture. Additionally, the RDMA network card module serves as an intermediary for high-speed remote memory access, handling the complexity of networked memory access transparently.
Solution Approach 2:
The patent creates remote memory page table entries that replicate the functionality of local page table entries, allowing the system to manage remote memory as if it were local. This copying approach enables the system to extend physical address space without requiring fundamental changes to the memory management architecture, as the remote memory is accessed through replicated control mechanisms.
3Adaptability or versatility
If page table entries are created only when accessed, then memory space is saved initially, but the system cannot handle addresses beyond physical address space
Solution Approach 1:
The patent segments the page table into local page table entries and remote memory page table entries. This segmentation allows the system to manage different types of memory addresses (local and remote) separately, enabling coverage of the full virtual address space including addresses beyond the physical address space while keeping the page table structure organized and manageable.
Solution Approach 2:
The patent extends the page table concept into a new dimension by introducing remote memory page table entries that map virtual addresses to remote physical addresses. This dimensional extension allows the page table to cover addresses beyond the traditional physical address space, providing adaptability for remote memory access while maintaining efficient memory usage through on-demand entry creation.
Data Source
AI summary
The disclosure discloses a memory space expansion method and apparatus, and an electronic device and a computer-readable storage medium, which are applied to a server. The method includes: receiving an access instruction configured with a virtual address, and querying whether there is a page table entry corresponding to the virtual address in a local page table and a remote page table; in response to the page table entry corresponding to the virtual address being not existed in the local page table and the remote page table, determining whether there is an unallocated physical address in the server; and in response to the unallocated physical address being not existed in the server, creating, on the basis of the physical address in a remote memory array apparatus, a remote memory page table entry corresponding to the virtual address.