Atomic Memory Lock Mechanism with Immediate Status Feedback
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Solution Overview
Problem
Current mechanisms for locking and unlocking memory accesses to shared memory do not provide immediate feedback on lock acquisition status, leading to inefficiencies in atomic memory operations.
Innovation Solution
A system and method that provide immediate feedback on lock status during read or write operations, allowing explicit lock or unlock commands for each atomic memory operation, and enabling lock bits to be shared across multiple memory locations to reduce false contentions due to memory address aliasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional load link and store-condition instructions are used to implement atomic memory operations, then memory access locking is achieved, but immediate feedback on lock acquisition status is not provided
Solution Approach 1:
The patent introduces a feedback mechanism where the lock status is immediately returned to the requestor along with the read data. When a read instruction with a lock command suffix is executed, the system atomically acquires the lock, retrieves the data, and returns both the data and a lock result indicating whether the lock was successfully acquired. This eliminates the need for separate lock status checks and provides immediate feedback on lock acquisition status.
2Reliability
If lock status is checked as a separate transaction prior to read-modify-write operation, then lock acquisition is ensured, but additional latency is introduced
Solution Approach 1:
The patent merges the lock acquisition operation with the read operation into a single atomic transaction. The read instruction is augmented with a lock command suffix that causes the memory system to atomically acquire the lock, perform the read, and return both the data and lock status in one operation. This eliminates the need for separate lock check transactions and reduces overall latency while maintaining reliability.
3Ease of operation
If a lock bit is allocated for each memory location, then precise locking control is achieved, but memory resources are consumed and false contentions increase
Solution Approach 1:
The patent implements a universal lock bit that can be shared among multiple memory locations through address aliasing. Instead of dedicating a separate lock bit to each memory location, a single lock bit serves multiple locations that may be accessed by different threads. This reduces the total number of lock bits required in the system while still providing effective locking control for atomic operations.
Solution Approach 2:
The patent changes the parameter of lock bit allocation from one-to-one (one lock bit per memory location) to many-to-one (multiple memory locations sharing one lock bit). This parameter change reduces the quantity of lock bits required in the system, decreasing memory resource consumption while maintaining the ability to provide precise locking control when needed.
4Quantity of substance
If memory address aliasing is allowed with shared lock bits, then resource efficiency is improved, but false memory location contentions increase
Solution Approach 1:
The patent introduces dynamic lock acquisition and release mechanisms where locks are acquired only when necessary for atomic operations and released immediately after completion. The system dynamically determines whether a lock is needed based on the specific operation being performed, and uses explicit lock and unlock commands to manage lock state. This dynamic approach reduces the duration and frequency of lock holdings, thereby reducing false contentions caused by address aliasing.
Data Source
AI summary
A system and method for locking and unlocking access to a shared memory for atomic operations provides immediate feedback indicating whether or not the lock was successful. Read data is returned to the requestor with the lock status. The lock status may be changed concurrently when locking during a read or unlocking during a write. Therefore, it is not necessary to check the lock status as a separate transaction prior to or during a read-modify-write operation. Additionally, a lock or unlock may be explicitly specified for each atomic memory operation. Therefore, lock operations are not performed for operations that do not modify the contents of a memory location.