Asynchronous FIFO Read Prediction for Latency Reduction
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Solution Overview
Problem
Asynchronous clock crossings between different clock domains in processing systems lead to data loss and increased latency due to improper management of data transfer, particularly in first-in-first-out (FIFO) buffers used between processing cores and data fabrics.
Innovation Solution
A method and apparatus that determine the timing separation between write headers and data in an asynchronous FIFO, allowing for feed-forward read predictions based on the clock frequency ratio between clock domains, enabling earlier consumption of read data by issuing a pipeline read transaction start signal before write data is valid, thereby reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional asynchronous FIFO management is used, then data transfer between clock domains is maintained, but read latency increases and processing efficiency decreases
Solution Approach 1:
The patent applies preliminary action by predicting when read data will be valid based on the timing separation between write header and write data, plus the clock frequency ratio. This allows the read transaction start signal to be issued in advance before the read data is actually valid, thereby reducing read latency without compromising data integrity across asynchronous clock domains
2Speed
If read transactions are initiated only when data is valid, then data accuracy is maintained, but system speed and processing efficiency are reduced
Solution Approach 1:
The patent employs feedback by using the determined timing separation between write header and write data, combined with the clock frequency ratio, to predict when read data will become valid. This predictive feedback mechanism enables the system to issue read transaction start signals proactively while maintaining data accuracy, thus improving system speed without sacrificing reliability
Data Source
AI summary
Methods and apparatus employ an asynchronous first-in-first-out buffer (FIFO), that includes a plurality of entries. Control logic determines a timing separation between a write header valid signal and corresponding write data valid signal for a write operation to an entry in the first-in-first-out buffer (FIFO) and performs a read of the corresponding data from the entry in the FIFO in the second clock domain, based on the determined timing separation of the write header valid signal and corresponding write data valid signal, and based on a clock frequency ratio between the first and second clock domains.