Memory Controller Variable Latency Acknowledgement
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Solution Overview
Problem
Phase change memory (PCM) devices face limitations in write and read operations due to variable latency periods, restricting their usage in memory systems, as they require monitoring progress and suspending operations, leading to slower performance and restricted operational flexibility.
Innovation Solution
A memory system with a memory operation controller that manages variable latency periods by providing an acknowledgement signal to indicate the end of the latency period, allowing for concurrent read and write operations and flexible timing for resuming suspended operations, thereby improving operational flexibility and reducing wait times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PCM is used as RAM replacement with conventional read/write operations, then non-volatile memory functionality is achieved, but write and read operations become slower due to variable latency periods and operation suspensions
Solution Approach 1:
The memory operation controller proactively manages the variable latency period by initiating preliminary actions such as detecting when latency is approaching completion and pre-positioning data or preparing read operations. This allows the system to minimize idle wait time during write operations and overlap operations where possible, thereby improving speed without sacrificing the non-volatile memory functionality.
2Ease of operation
If status registers are polled to monitor write operation completion, then operational control is maintained, but productivity decreases due to regular polling interruptions
Solution Approach 1:
The memory operation controller implements an optimized feedback mechanism that monitors write operation progress through status registers but intelligently adjusts polling frequency based on the variable latency period. Instead of rigid regular polling, the controller adapts its monitoring strategy to match the actual operation state, maintaining operational control while minimizing unnecessary interruptions and maximizing productivity.
3Reliability
If write operations are suspended for read operations, then data integrity is maintained, but loss of time occurs due to operation resumption delays
Solution Approach 1:
The memory operation controller dynamically adjusts operation scheduling based on the variable latency period and current operation state. Instead of rigid suspension rules, the controller evaluates whether reads can be performed during write latency periods or if suspensions are truly necessary, dynamically optimizing the balance between data integrity and time efficiency.
Solution Approach 2:
The controller strives to maintain continuous useful action by identifying opportunities to perform read operations during the variable latency period of write operations, rather than suspending writes. This overlap of operations reduces total execution time while maintaining data integrity through proper controller management of the memory interface.
Data Source
AI summary
Apparatuses and methods for performing memory operations are described. In an example apparatus, a memory is configured to receive a memory instruction and perform a memory operation responsive to the memory instruction. The memory is further configured to provide an acknowledgement indicative of an end of the variable latency period wherein the acknowledgement includes information related to an acceptance of a memory instruction. Data associated with the memory instruction is exchanged with the memory following the acknowledgement. In an example method a read instruction and an address from which read data is to be read is received. A write operation is suspended responsive to the read instruction and an acknowledgement indicative of an end of the variable latency period is provided. Read data for the read instruction is provided and the write operation is continued to be suspended for a hold-off period following completion of the read operation.