Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 11/11/2022
Public

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3.5.6.1. Implementation Details

When the processor writes to any coherent memory location, the SCU ensures that the relevant data is coherent (updated, tagged or invalidated). Similarly, the SCU monitors read operations from a coherent memory location. If the required data is already stored within the other processor’s L1 cache, the data is returned directly to the requesting processor. If the data is not in L1 cache, the SCU issues a read to the L2 cache. If the data is not in the L2 cache memory, the read is finally forwarded to main memory. The primary goal is to maximize overall memory performance and minimize power consumption.

The SCU maintains bidirectional coherency between the L1 data caches belonging to the processors. When one processor performs a cacheable write, if the same location is cached in the other L1 cache, the SCU updates it.

Non‑coherent data passes through as a standard read or write operation.

If multiple CPUs attempt simultaneous access to the L2 cache, the SCU arbitrates among them.