Address Translation Cache Write Permission Prefetching
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Solution Overview
Problem
Current interconnect architectures in computing systems face challenges in efficiently managing address translations and permissions for devices, particularly in scenarios where devices may need to switch between read and write access, leading to increased complexity and power consumption.
Innovation Solution
The introduction of a Potential Write (PW) flag in Address Translation Request messages allows devices to anticipate and request write permissions proactively, reducing the need for multiple translation requests by treating requests with the PW flag set differently based on the dirty bit status in page tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If devices request write permissions through multiple translation requests, then write access is granted, but transaction overhead and power consumption increase
Solution Approach 1:
The patent applies preliminary action by introducing a Potential Write (PW) flag that allows devices to anticipate and request write permissions in advance. When a device sets the PW flag in an address translation request, the translation agent proactively grants write permission if the dirty bit is set, eliminating the need for subsequent follow-up requests. This proactive approach reduces transaction overhead and power consumption while ensuring reliable write permission management.
2Adaptability or versatility
If devices switch between read and write access, then flexibility is improved, but address translation complexity increases
Solution Approach 1:
The patent applies dynamics by enabling flexible access permission switching through the PW flag mechanism. Devices can dynamically transition between read-only and read-write access by setting or clearing the PW flag in address translation requests. The translation agent dynamically adjusts permissions based on the dirty bit status, allowing adaptive access control without increasing translation management complexity. This dynamic approach maintains versatility while simplifying the translation process.
Data Source
AI summary
Systems, methods, and devices can include circuitry or computer program products to receive a memory address translation request message from a downstream connected device; identify, from the memory address translation request message, a permission indication that the device intends to perform a write access to one or more memory address locations specified in the memory address translation request message; identify, from an address translation and protection table (ATPT), a dirty bit value associated with the one or more memory address locations; and transmit a translation of the one or more memory address locations and a read or read+write permission to the device based on the permission indication in the memory address translation request message and the dirty bit.