Memory Block Power Control via Access Prediction
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Solution Overview
Problem
Conventional memory power management solutions in integrated circuits face challenges in reducing power consumption while maintaining performance, as they often lead to unnecessary power dissipation and latency issues due to inefficient power mode transitions and excessive power usage in multi-bank memory systems.
Innovation Solution
A high-performance memory control system that employs a low power memory mode with maximum granularity and low latency transitions by using access observers and power control units to selectively manage power states of memory blocks within each bank, exploiting inherent delays in the interconnect and RAM access delays to minimize unnecessary power state changes and reduce power-up latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional retention mode operation is used to reduce power consumption, then power savings are achieved, but unnecessary power dissipation occurs when memory elements are kept in standby and power-up latency is imposed on memory accesses
Solution Approach 1:
The patent applies preliminary action by predicting future memory access patterns and proactively maintaining memory blocks in active state before actual access occurs. The prediction unit analyzes access patterns and generates predictions that trigger power control signals to keep predicted accessed blocks active, eliminating power-up latency when accesses occur. This resolves the contradiction by preparing memory blocks in advance based on predicted usage, so no latency is incurred when predictions are accurate.
Solution Approach 2:
The patent implements dynamics by making power state management adaptive and dynamic rather than static. The system continuously monitors actual access patterns, compares them with predictions, and dynamically adjusts power states of memory blocks. When predictions are inaccurate or access patterns change, the system dynamically transitions blocks between active and retention states, optimizing the balance between power consumption and access latency in real-time.
2Productivity
If memory banks are organized to enable concurrent accesses by multiple master devices, then memory throughput is increased, but complexity and performance penalty for pathway delays over the interconnect increase
Solution Approach 1:
The patent applies segmentation by dividing the memory system into independent memory blocks within banks, each with its own power control. This segmentation allows selective power management of individual blocks rather than entire banks, reducing the complexity of interconnect routing and control logic while maintaining throughput. Each block can be independently powered or placed in retention, simplifying the overall system architecture.
Solution Approach 2:
The patent implements local quality by applying different power states to different memory blocks based on their specific access patterns and predictions. Instead of uniformly managing power across entire banks, the system applies localized power control to individual blocks, allowing some blocks to be active while others are in retention. This localized approach reduces interconnect complexity by enabling finer-grained control without requiring complex bank-level coordination.
3Loss of energy
If a low power retention mode is used to power down periphery logic, then power consumption is reduced, but memory content cannot be accessed immediately
Solution Approach 1:
The patent applies preliminary action by using the prediction unit to forecast which memory blocks will be accessed and maintaining them in active state in advance. This proactive approach ensures that when access is needed, the memory content is already available immediately, eliminating the speed penalty associated with retention mode. The system performs the action of keeping memory active before the access request arrives.
Solution Approach 2:
The patent implements feedback through the comparison unit that continuously compares actual access patterns with predicted patterns. This feedback loop allows the system to learn from prediction accuracy and adjust future predictions, improving the ability to correctly identify which blocks should remain active. The feedback mechanism refines the prediction over time, enhancing both power savings and access speed by reducing false predictions.
Data Source
AI summary
A power control system, method, and architecture are disclosed for a multi-bank memory which provides independent, concurrent memory access to at least one memory block in each memory bank by using observation circuits to monitor bus masters connected over bus master interface signals to an interconnect for memory access requests to the multi-bank memory and to provide notifications to a power control circuitry that a valid memory access request was issued by a bus master over the bus master interface, where the power control circuitry processes the notifications received from each observation circuit and generates therefrom power control signals that are provided directly to each memory block and to bypass the interconnect, thereby separately controlling a power state for each memory block with power-up control signals that arrive at each memory block at or before a memory access request sent over the interconnect.