Early Demotion Logic Circuitry for Multi-Level Memory Page Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-level memory systems, the process of page demotion from near memory to far memory can create bottlenecks due to instantaneous and reactionary data movement decisions, leading to performance degradation as the CPU instruction execution pipeline is stalled waiting for TLB updates.
Innovation Solution
The implementation of early demotion logic circuitry within the memory controller, which proactively demotes pages expected to be evicted and uses an early write remapping buffer to allow hardware operation before TLB updates, enabling batch updates and reducing the frequency of CPU stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If instantaneous and reactionary data movement decisions are implemented for page demotion, then memory management responsiveness is improved, but CPU instruction execution pipeline performance deteriorates due to frequent stalls waiting for TLB updates
Solution Approach 1:
The patent implements early demotion logic that proactively demotes pages before the system software would normally command their demotion. By performing page demotion in advance based on predicted eviction patterns, the system prepares memory transitions beforehand, reducing the need for urgent data movement decisions that stall the CPU pipeline. The early write remapping buffer stores remapping information ahead of TLB updates, allowing CPU operations to proceed without waiting for synchronization.
2Speed
If frequent page demotion is performed to maintain near memory performance, then near memory access speed is improved, but system bottlenecks increase due to continuous data movement between memory levels
Solution Approach 1:
The patent introduces an early write remapping buffer as an intermediary structure between the memory controller and the TLB. This buffer stores remapping information for demoted pages before the TLB is updated, allowing the memory system to proceed with demotion operations without immediately blocking CPU access. The buffer acts as a decoupling mechanism that smooths out the data movement operations, reducing system bottlenecks while maintaining near memory performance.
3Productivity
If batch TLB updates are implemented to reduce update frequency, then CPU stall frequency is reduced, but memory address translation accuracy may be compromised during the batch update period
Solution Approach 1:
The early write remapping buffer serves as an intermediary that preserves address translation accuracy during batch updates. When pages are demoted, their remapping information is immediately stored in the buffer, ensuring that even before the TLB is updated, the correct mapping information is available. This allows batch TLB updates to proceed without compromising translation accuracy, as the buffer maintains the authoritative mapping data throughout the update process.
Data Source
AI summary
An apparatus is described that includes a memory controller to couple to a multi-level memory characterized by a faster higher level and a slower lower level. The memory controller having early demotion logic circuitry to demote a page from the higher level to the lower level without system software having to instruct the memory controller to demote the page and before the system software promotes another page from the lower level to the higher level.