Understanding the ACE Protocol’s Transaction Domains
Hello everyone,
I’ve been diving into the ACE protocol and its transaction domains, specifically the Non-shareable, Inner, Outer, and System domains. This has been a fascinating topic, but I have a few questions that I hope the community can help clarify.
First, I want to ensure I’m interpreting the Inner and Outer domains correctly. Suppose we have three cores—Core0, Core1, and Core2—sharing a Cache Line ‘a’. Core0-1 belongs to the Inner domain, while Core0-2 is in the Outer domain. If Core0 initiates an Invalid operation with ARDOMAIN 01 (Inner) for Cache Line ‘a’, would this invalidate the cache line in Core1 without affecting Core2? If so, does this mean Core0’s state of ‘a’ is no longer considered Unique? I’m curious if this understanding is accurate.
Next, I’d like to know who defines the boundaries between Inner and Outer domains. Is this specified at the CPU level or determined by the architect during system design? Additionally, are these divisions arbitrary, or are there specific requirements they must meet? For example, I’ve read that a cluster might be divided into Inner domains, allowing multiple Inners within an Outer. Does this make sense, or am I misunderstanding the hierarchy?
I’ve also been experimenting with different configurations to see how these domains interact in real-world scenarios. For instance, setting up a multi-core system and observing cache coherence behavior under various domain assignments has been both enlightening and a bit perplexing.
If anyone has insights or resources that could shed more light on these questions, I’d greatly appreciate it. I’m eager to deepen my understanding and ensure I’m applying these concepts correctly in my projects.
Thanks in advance for your guidance and expertise!
Best regards,
[Your Name]