Security Controller Dual Read Paths Latency
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Solution Overview
Problem
Security controllers face increased latency and reduced performance in handling transaction requests due to the need for security checking, which can also lead to blocked pending requests and inefficient handling of outstanding transactions.
Innovation Solution
A security controller with first and second read request paths, where the first path performs security checking before issuing requests and the second path issues requests without waiting for security checking results, storing tracking data for later verification, allowing for a balance between low latency and high transaction handling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If security checking is performed before issuing read requests, then security violations are prevented, but response latency increases
Solution Approach 1:
The read request path is segmented into two separate paths: a first read request path that performs security checking before issuing requests, and a second read request path that issues requests without waiting for security checking results. This segmentation allows the system to handle different types of read requests through different paths, preventing security violations while reducing latency for time-critical requests.
Solution Approach 2:
Security checking is performed in advance for the first read request path, so that by the time the request needs to be issued, the security decision is already made. This preliminary action prevents security violations from causing delays during request issuance.
2Reliability
If security checking is performed synchronously, then security is ensured, but the number of outstanding transaction requests that can be handled decreases
Solution Approach 1:
The system segments read request handling into two paths: the first path performs synchronous security checking for requests where security is the priority, while the second path allows requests to be issued immediately with asynchronous security checking, thereby increasing the number of outstanding transaction requests that can be handled simultaneously.
Solution Approach 2:
For the second read request path, security checking results are fed back asynchronously after the request is issued. This feedback mechanism allows the system to maintain a high number of outstanding requests while still performing security verification, with the security result used to mask data if violations are detected.
3Loss of time
If the second read request path is used for low latency, then response time is reduced, but security violations may occur undetected
Solution Approach 1:
The second read request path implements asynchronous feedback where security checking results are returned after the request is issued. This allows the request to proceed with low latency while still maintaining security verification, with the feedback used to mask data if security violations are detected.
Solution Approach 2:
A tracking data store acts as an intermediary between the second read request path and the response path. It stores security checking results and associates them with corresponding read requests, enabling the response path to modify responses based on security violations without blocking the original request processing.
4Productivity
If more read request paths are added to handle both high bandwidth and low latency, then performance is improved, but device complexity increases
Solution Approach 1:
Both the first and second read request paths share common functionality for security checking and response handling. The security checking mechanism and response path are designed to serve both paths, reducing overall system complexity despite having multiple request paths.
Solution Approach 2:
The system merges the security checking functionality and response handling into shared components that serve both read request paths. This consolidation reduces device complexity by eliminating duplication while maintaining the performance benefits of having separate paths for different latency requirements.
Data Source
AI summary
A security controller has first and second read request paths for performing security checking of read requests received from a master device and for controlling issuing of the read request to a safe device. If the first read request path is selected for an incoming read request then the first read request path controls issuing of the read request in dependence on result of the security checking. If the second read request path is selected, then the incoming read request is issued without waiting for a result of the security checking, and tracking data is stored indicating the result of the security checking. When receiving a response to a read request issued using the second read request path, a response path modifies the response to mask read data if the tracking data stored for the corresponding read request indicates that a security violation occurred.