PowerFlex: CPU Idle State Configuration Guidance

Summary: During multiple PowerFlex releases, the default CPU idle-state configuration has changed. This has introduced confusion for customers and field teams who are seeing differences between expected vs. deployed configurations. These variations often lead to unnecessary support cases or node configuration adjustments. ...

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
Check out other resources

Instructions

Overview

Observed CPU idle-state configuration differs between nodes in the same cluster.

Tools or validation checks flag discrepancies that appear to violate best-practice performance settings. Also, a misinterpretation that differences indicate performance risk or misconfiguration.

 

Technical Details

PowerFlex controls CPU idle-state behavior using two boot loader parameters:

  • intel_idle.max_cstate

    Value Behavior
    1 Prevents deeper CPU idle states using the intel_idle driver
    0 Disables intel_idle and defers to the ACPI driver
    Effective Result: Same restriction of deep idle states

  • processor.max_cstate

    Value Behavior
    0 or 1 Prevents deeper ACPI idle states
    Effective Result: No functional performance difference

These values restrict deep CPU sleep states, which can increase wake-up latency and cause I/O performance jitter.

Testing by PowerFlex Performance Engineering confirms that any combination of 0 or 1 for these two parameters results in equivalent behavior on PowerFlex systems.

Therefore, variations in observed settings do not imply performance degradation or configuration drift.

 

Validated Equivalent Combinations

All the following configurations conform to PowerFlex best practices:

No remediation is necessary when encountering any of the below configuration variations.

Combination #1 - intel_idle.max_cstate = 0 ; processor.max_cstate = 0

Combination #2 - intel_idle.max_cstate= 0 ; processor.max_cstate = 1

Combination #3 - intel_idle.max_cstate= 1 ; processor.max_cstate = 0

Combination #4 - intel_idle.max_cstate= 1 ; processor.max_cstate = 1

These settings are automatically applied during deployment using PowerFlex Manager.

They are validated during lifecycle operations by the SCR tool (vX.Y and above). Manual modification is not required unless SCR explicitly flags a non-conforming configuration.

Affected Products

PowerFlex rack, ScaleIO
Article Properties
Article Number: 000385600
Article Type: How To
Last Modified: 30 Oct 2025
Version:  1
Find answers to your questions from other Dell users
Support Services
Check if your device is covered by Support Services.