Hazard Checking Control in Interconnect Circuitry
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Solution Overview
Problem
As system-on-chip integrated circuits increase in complexity, the interconnect circuitry faces challenges in efficiently communicating access transactions while preventing hazards such as transaction ordering violations and coherence breakdowns, leading to increased latency and energy consumption.
Innovation Solution
The interconnect circuitry incorporates a reorder buffer for reordering access transactions, coupled with hazard checking and check suppression circuitry that determines the necessity of hazard checks based on state variables, selectively suppressing checks when unnecessary to improve efficiency and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hazard checks are performed on all access transactions in the reorder buffer, then transaction ordering violations and coherence breakdowns are prevented, but latency and energy consumption increase
Solution Approach 1:
The patent changes the operational parameters of hazard checking by introducing state variables that track the state of other transactions in the reorder buffer. Based on these state variables, the hazard check circuitry dynamically adjusts whether to perform checks on incoming transactions. This parameter change allows the system to maintain reliability when needed while reducing latency when the buffer state indicates safety
Solution Approach 2:
The patent implements dynamic hazard checking where the decision to perform or suppress checks is not static but adapts based on the current state of the reorder buffer. The check suppression circuitry continuously monitors state variables and dynamically controls the hazard check process, enabling the system to respond to changing conditions and optimize performance in real-time
2Reliability
If hazard checks are performed on all access transactions in the reorder buffer, then transaction ordering violations and coherence breakdowns are prevented, but energy consumption increases
Solution Approach 1:
The patent changes the operational parameters of hazard checking by introducing state variables that track the state of other transactions in the reorder buffer. Based on these state variables, the hazard check circuitry dynamically adjusts whether to perform checks on incoming transactions. This parameter change allows the system to maintain reliability when needed while reducing energy consumption when the buffer state indicates safety
Solution Approach 2:
The patent applies partial hazard checking by performing checks only when necessary based on the buffer state, rather than checking all transactions uniformly. The check suppression circuitry determines that partial checking is sufficient in certain states, reducing energy consumption while maintaining adequate reliability through selective application of the hazard checking function
3Productivity
If the interconnect circuitry complexity increases to handle more transactions, then system performance improves, but hazard checking overhead increases
Solution Approach 1:
The patent segments the hazard checking function into distinct components: state variable tracking, check suppression control, and hazard check execution. This segmentation allows each component to be optimized independently and enables the system to handle more transactions by distributing the checking overhead across multiple manageable units rather than a monolithic complex circuit
Data Source
AI summary
A system-on-check integrated circuit 2 includes interconnect circuitry 4 connecting a plurality of transaction sources to a plurality of transaction destinations. The interconnect circuitry 4 includes a reorder buffer for buffering access transactions and hazard checking circuitry 46, 48, 50, 52 for performing hazard checks, such as point-of-serialization checks and identifier reuse checks. Check suppression circuitry 62, 64, 66, 68 serves to suppress one or more hazard checks depending upon one or more state variables that themselves depend upon access transactions other than the access transaction for which the hazard checking is or is not to be suppressed. As an example, hazard checking may be suppressed if it is known that there are no other access transactions currently buffered within the reorder buffer 26 or alternatively no other access transactions from the same transaction source buffered within the reorder buffer 26.