Dynamic QoS Threshold Adjustment for Display Memory Stress

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Solution Overview

Problem

Digital systems face challenges in balancing the performance requirements of real-time and non-real-time devices through Quality of Service (QoS) management, leading to inefficient memory bandwidth utilization and increased power consumption due to conservative QoS level determinations based on worst-case scenarios.

Innovation Solution

A display control unit dynamically adjusts QoS levels by comparing image data buffers to thresholds, updating these thresholds based on memory stress levels to optimize QoS usage, reducing unnecessary higher QoS levels during low memory loads and ensuring proper operation during high loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conservative QoS levels are used based on worst-case scenarios, then reliability of real-time devices is improved, but memory bandwidth utilization deteriorates and power consumption increases

Engineering Contradiction:

Improvereliability of real-time devicesVSAvoidmemory bandwidth utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements dynamic QoS threshold adjustment by monitoring memory stress levels in real-time. The display control unit receives memory stress indications from the memory controller and dynamically updates QoS thresholds based on current system conditions. When memory stress is high, conservative thresholds are applied; when stress is low, less conservative thresholds are used, allowing flexible adaptation to changing conditions and resolving the contradiction between reliability and productivity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the QoS threshold parameters dynamically based on memory stress levels. Instead of using fixed conservative thresholds, the patent adjusts threshold values according to actual memory controller busy-ness and bandwidth availability. This parameter adaptation allows the system to maintain reliability when needed while improving memory bandwidth utilization during periods of lower stress.

Inventive Principle:

Principle #35Parameter changes

2Speed

If higher QoS levels are issued frequently, then real-time device performance is improved, but overall system performance deteriorates due to bypassed memory operations

Engineering Contradiction:

Improvereal-time device performanceVSAvoidoverall system performance

Core Design Contradiction:

SpeedVSProductivity

Solution Approach 1:

The patent dynamically adjusts QoS threshold parameters based on memory stress levels. When memory stress is low, higher QoS levels can be issued more frequently without significantly impacting overall system performance because the memory controller has available bandwidth. When stress is high, thresholds become more conservative, preventing excessive high-QoS requests that would bypass efficient memory operations. This dynamic parameter adjustment resolves the contradiction between real-time device speed and overall system productivity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conservative QoS determination is used, then erroneous operation in real-time devices is prevented, but power consumption increases due to reduced memory bandwidth utilization

Engineering Contradiction:

Improveprevention of erroneous operationVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts QoS thresholds based on real-time memory stress monitoring. During high memory stress periods, conservative thresholds are applied to prevent erroneous operation in real-time devices. During low stress periods, less conservative thresholds reduce the frequency of high-QoS requests, improving memory bandwidth utilization and reducing power consumption. This dynamic adaptation resolves the contradiction between reliability and energy efficiency.

Inventive Principle:

Principle #15Dynamics

4Stability of the object's composition

If fixed thresholds are used for QoS determination, then system behavior is predictable, but adaptability to changing memory loads deteriorates

Engineering Contradiction:

Improvepredictability of system behaviorVSAvoidadaptability to changing memory loads

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic threshold adjustment while maintaining systematic control. The display control unit receives memory stress indications and systematically updates QoS thresholds based on current conditions. This dynamic approach maintains predictability through structured threshold management while simultaneously improving adaptability to changing memory loads, resolving the contradiction between stability and versatility.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9019291B2Multiple quality of service (QoS) thresholds or clock gating thresholds based on memory stress level

Publication Date: 2015.04.28 APPLE INC

AI summary

In an embodiment, a display control unit is configured to transmit read operations to the memory in the system to read image data for processing, and may employ QoS levels with the read operations to ensure that enough data is provided to satisfy the real time display requirements. To determine which QoS level to use for a given read request, the display control unit may be configured to compare an amount of image data in the display control unit (e.g. in various input and/or output buffers in the display control unit) to one or more thresholds. The display control unit may also be configured to dynamically update the thresholds based on a memory stress level in the memory controller.