Cache Flush Energy Measurement for Write-Back Configuration

Solution Overview

Problem

In information handling systems, enabling write-back caching with persistent memory is challenging due to the time required to flush 'dirty' cache lines from the cache to memory exceeding the system's hold-up time, leading to performance sacrifices, especially when the cache or address range of the persistent memory region cannot be configured as write-back.

Innovation Solution

An information handling system that includes a processor, a management controller, and a BIOS configured to determine the energy required to flush the cache to memory during a power loss and compare it with the available hold-up energy, allowing the cache to be configured as write-back if sufficient energy is available, or switching to write-through mode if not, thereby optimizing cache configuration based on energy availability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cache is configured as write-back mode, then the system performance is improved, but the cache flush time exceeds the available hold-up time causing data loss risk

Engineering Contradiction:

Improvesystem performanceVSAvoidcache flush time

Core Design Contradiction:

ProductivityVSDuration of action of moving object

Solution Approach 1:

The system performs preliminary measurements during boot to determine the actual cache flush time and energy requirements before configuring the cache mode. By measuring the flush operation in advance and comparing it with the hold-up time capability, the system can proactively configure the appropriate cache mode (write-back or write-through) to avoid data loss while optimizing performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically changes the cache configuration parameter based on measured conditions. During boot, it measures the cache flush time and energy consumption, then adjusts the cache mode parameter accordingly - setting it to write-back mode when flush time is within hold-up limits, and write-through mode when it exceeds the limits, thus adapting the system to the actual power supply characteristics.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the cache flush time is reduced to fit within hold-up time, then data persistence is ensured, but system performance deteriorates due to write-through mode requirement

Engineering Contradiction:

Improvedata persistenceVSAvoidsystem performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary measurements during boot to determine the actual cache flush time and energy requirements before configuring the cache mode. By measuring the flush operation in advance and comparing it with the hold-up time capability, the system can proactively configure the appropriate cache mode (write-back or write-through) to avoid data loss while optimizing performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically changes the cache configuration parameter based on measured conditions. During boot, it measures the cache flush time and energy consumption, then adjusts the cache mode parameter accordingly - setting it to write-back mode when flush time is within hold-up limits, and write-through mode when it exceeds the limits, thus adapting the system to the actual power supply characteristics.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the hold-up time is extended to accommodate cache flush operations, then write-back caching becomes feasible, but the power supply complexity and cost increase

Engineering Contradiction:

Improvecache flush capabilityVSAvoidpower supply complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system uses its own operational characteristics (cache flush time and energy consumption) to determine the appropriate configuration. By measuring these parameters during boot and using them to configure the cache mode, the system serves itself without requiring external intervention or complex power supply modifications, thus avoiding increased power supply complexity and cost.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system dynamically changes the cache configuration parameter based on measured conditions. During boot, it measures the cache flush time and energy consumption, then adjusts the cache mode parameter accordingly - setting it to write-back mode when flush time is within hold-up limits, and write-through mode when it exceeds the limits, thus adapting the system to the actual power supply characteristics.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9965289B2Systems and methods for real-time cache flush measurements in an information handling system

Publication Date: 2018.05.08 DELL PROD LP

AI summary

In accordance with embodiments of the present disclosure, a method may include, during boot of an information handling system, determining a first amount of energy required by the information handling system to flush a cache integral to the information handling system to memory integral to the information handling system in response to a power loss of one or more power supplies for supplying electrical energy to the information handling system, determining whether a second amount of energy available for hold-up of one or more power supplies in response to the power loss exceeds the first amount of energy, and responsive to determining whether the second amount of energy exceeds the first amount of energy, configuring the cache.