Monitoring Circuitry for Write Transaction Authorization
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Solution Overview
Problem
Current data processing systems face inefficiencies in monitoring and authorizing write transactions, leading to imprecise exceptions and processing stalls, particularly when trying to distinguish between privileged and non-privileged software or processor operations, and require complex mechanisms to ensure precise aborts and maintain forward progress.
Innovation Solution
The implementation of monitoring circuitry that selectively authorizes write transactions by identifying associated addresses and storing transaction data in an intermediate storage element, allowing for reissue without re-executing the corresponding write instruction, enabling precise exception behavior and reducing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If write transactions are monitored and authorized by a more privileged operating system, then system security and transaction control are improved, but processing efficiency deteriorates due to transaction stalls and blocking
Solution Approach 1:
The patent implements preliminary action by buffering write transaction data in an intermediate storage element before authorization is complete. This allows the system to prepare transaction data in advance and maintain it for potential reissue, preventing the need to re-execute instructions after authorization delays
Solution Approach 2:
The patent introduces an intermediate storage element as a mediator between the bus fabric and the authorized write transaction destination. This intermediary component holds transaction data during the authorization process, enabling the bus to continue processing other transactions while maintaining the authorized transaction's data for later completion
2Productivity
If speculative execution is permitted to maintain forward progress, then processing speed is improved, but system reliability deteriorates due to imprecise exceptions and data loss
Solution Approach 1:
The patent applies preliminary action by pre-buffering write transaction data in the intermediate storage element before speculative execution commits. This ensures that if an exception occurs, the data is already preserved and can be used for precise exception handling without requiring instruction re-execution
Solution Approach 2:
The patent uses copying by creating a buffer copy of the write transaction data in the intermediate storage element. This copy serves as a backup that preserves the original transaction data, enabling precise exception behavior while allowing speculative execution to proceed without fear of data loss
3Measurement precision
If write transactions are strongly ordered to ensure precise aborts, then exception precision is improved, but processing efficiency deteriorates due to transaction blocking
Solution Approach 1:
The patent introduces an intermediate storage element as a mediator that decouples the strong ordering requirement from the bus transaction flow. The intermediate storage holds transaction data while the bus continues to service other transactions, maintaining precise abort capability without blocking the transaction stream
Solution Approach 2:
The patent implements preliminary action by pre-storing transaction data in the intermediate storage element before the transaction completes. This allows the system to maintain precise exception behavior (by having the data ready) while allowing subsequent transactions to proceed without waiting for the current transaction to fully complete
Data Source
AI summary
Apparatus for processing data is provided comprising processing circuitry and monitoring circuitry for monitoring write transactions and performing transaction authorizations of certain transactions in dependence upon associated memory addresses. The processing circuitry is configured to enable execution of a write instruction corresponding to a write transaction to be monitored to continue to completion while the monitoring circuitry is performing monitoring of the write transactions and the monitoring circuitry is arranged to cause storage of write transaction data in an intermediate storage element for those transactions for which an authorization is required. Storage of write transaction data in an intermediate storage element enables the write transaction to be reissued in dependence upon the result of the transaction authorization although the corresponding write instruction has already completed.