Private Cache Sharing in Power-Gated SoC Agents
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Solution Overview
Problem
Current SoC designs waste resources when power-gating agents, as their cache memory is shut down, while other agents may need increased memory capacity or bandwidth, leading to inefficiencies in power consumption reduction techniques.
Innovation Solution
Implementing a mechanism to share the private cache of a power-gated agent with other agents in a System on Chip (SoC) by detecting specific conditions, such as power-gating or shutdown, and allocating non-coherent memory requests to another agent's private cache, with control logic determining when to allocate and evict data based on availability and need.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an agent is power-gated or shut down to reduce power consumption, then power consumption is reduced, but the cache memory becomes unavailable to other agents causing resource waste
Solution Approach 1:
The patent enables a cache memory originally dedicated to a single agent to serve multiple agents by detecting when the original agent is power-gated or shut down. The cache transitions from single-agent exclusivity to multi-agent shared access, allowing other agents to utilize the cached data when the original owner is inactive, thus resolving the contradiction between power savings and resource availability
Solution Approach 2:
The cache sharing mechanism dynamically adjusts cache accessibility based on the operational state of the owning agent. When the agent is active, the cache remains private; when the agent is power-gated or shut down, the cache becomes shared with other agents. This dynamic state-dependent behavior allows the system to optimize between power consumption and resource utilization in real-time
2Use of energy by moving object
If an agent's private cache is shut down when powered down, then power consumption is reduced, but memory capacity and bandwidth are reduced for other agents
Solution Approach 1:
The cache memory serves dual purposes: it functions as private cache when the owning agent is active, and as shared memory resource when the agent is power-gated or shut down. This multi-functionality ensures that the cache continues to contribute to system productivity even when not needed by its original owner, eliminating the waste of available memory capacity and bandwidth
Solution Approach 2:
When an agent is power-gated or shut down, the system recovers the cache memory resource by making it available to other agents. Instead of permanently losing the cache capacity when an agent is deactivated, the system discards the exclusive ownership and recovers the resource for reuse by other active agents, maintaining overall system productivity
Data Source
AI summary
Systems, processors, and methods for sharing an agent's private cache with other agents within a SoC. Many agents in the SoC have a private cache in addition to the shared caches and memory of the SoC. If an agent's processor is shut down or operating at less than full capacity, the agent's private cache can be shared with other agents. When a requesting agent generates a memory request and the memory request misses in the memory cache, the memory cache can allocate the memory request in a separate agent's cache rather than allocating the memory request in the memory cache.