[talos] Set cpu frequency scheduler to performance by nbykov0 · Pull Request #1898 · cozystack/cozystack

nbykov0 · Jan 21, 2026

What this PR does

Sets default cpu frequency scheduler to performance.
Disables cpu energy saving options.

Release note

Default cpu frequency scheduler set to performance.
Cpu energy saving options disabled.

Summary by CodeRabbit

Chores
- Added kernel boot parameters to installable and image profiles (ISO, installer, metal, nocloud) to favor performance-oriented CPU governor and adjust idle handling, improving runtime performance and responsiveness.
- Initramfs/kernel-style profiles remain unchanged (no extra boot parameters applied).

coderabbitai · Jan 21, 2026

📝 Walkthrough

Walkthrough

A profile generation script was updated to inject a customization block containing three extra kernel arguments. Several Talos profile YAML files now include that customization block (iso, installer, metal, nocloud); initramfs and kernel remain without kernel args or only whitespace changes.

Changes

Cohort / File(s)	Summary
Profile generation script `packages/core/talos/hack/gen-profiles.sh`	Adds a `customizationDefinition` heredoc and logic to apply a `customization` block (extraKernelArgs) for iso, installer, metal, and nocloud profiles; leaves initramfs/kernel customization empty.
Talos profile YAMLs — with customization `packages/core/talos/images/talos/profiles/iso.yaml`, `packages/core/talos/images/talos/profiles/installer.yaml`, `packages/core/talos/images/talos/profiles/metal.yaml`, `packages/core/talos/images/talos/profiles/nocloud.yaml`	Inserted a `customization` section containing `extraKernelArgs`: `cpufreq.default_governor=performance`, `amd_pstate=active`, and `intel_idle.max_cstate=0`.
Talos profile YAMLs — whitespace only `packages/core/talos/images/talos/profiles/initramfs.yaml`, `packages/core/talos/images/talos/profiles/kernel.yaml`	Minor formatting: added a blank line after the `version` field; no functional customization added.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 I nudged three args into each boot song,
Governor, AMD, idle—short and strong,
Profiles hopping into streamlined chore,
Quick boots, happy kernels—let's explore!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Set cpu frequency scheduler to performance' directly matches the main objective of the PR, which is to set the default CPU frequency scheduler to performance mode.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch talos-cpu-freq-scaling

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gemini-code-assist · Jan 21, 2026

Summary of Changes

Hello @nbykov0, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request standardizes the CPU performance settings across various Talos profiles by configuring the kernel to prioritize performance over energy efficiency. By setting the CPU frequency governor to 'performance' and disabling specific energy-saving mechanisms, the changes aim to ensure that Talos systems consistently operate at their maximum potential, which is crucial for workloads requiring predictable and high computational throughput.

Highlights

CPU Performance Governor: The default CPU frequency governor is now set to 'performance' across various Talos profiles to ensure consistent high clock speeds and prevent throttling.
Energy Saving Options Disabled: CPU energy saving features, specifically amd_pstate and intel_idle.max_cstate, are explicitly disabled to ensure maximum CPU performance without power-saving interventions.

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Code Review

This pull request updates Talos profiles to enhance performance by setting the CPU frequency governor to performance and disabling certain CPU power-saving features. The changes are made in the profile generation script and propagated to all generated profile YAML files. While the intent to boost performance is clear, one of the chosen kernel parameters, intel_idle.max_cstate=0, is very aggressive. My review includes a comment highlighting the potential negative side effects of this setting, such as increased power consumption and potential impacts on Intel Turbo Boost frequencies, and suggests a more balanced alternative.

packages/core/talos/hack/gen-profiles.sh

Signed-off-by: nbykov0 <166552198+nbykov0@users.noreply.github.com>

lexfrei

Overall: The kernel parameters are valid and match Talos Performance Tuning documentation. The kernel config confirms all required options are built-in (CONFIG_CPU_FREQ_GOV_PERFORMANCE=y, CONFIG_X86_AMD_PSTATE=y, CONFIG_INTEL_IDLE=y).

A few concerns:

nocloud profile: This profile is typically used for cloud/VM environments (e.g., OpenStack). Inside a VM, the guest usually has no direct access to CPU frequency scaling or hardware C-states — the hypervisor manages that. Applying intel_idle.max_cstate=0 and amd_pstate=active inside a VM is either a no-op or potentially counterproductive. Is there a reason to include these kernel args in the nocloud profile?
intel_idle.max_cstate=0 disables the intel_idle driver entirely, causing the kernel to fall back to acpi_idle, which also has its own C-states. For complete C-state control, processor.max_cstate=0 would also be needed. This is consistent with the Talos docs (which only mention intel_idle.max_cstate=0), but worth being aware of.
Minor: Trailing whitespace after ;; in the initramfs|kernel case block (line 51 in the diff).

Revised review: the nocloud concern was incorrect (nocloud is also used for bare-metal provisioning). Submitting updated review.

lexfrei

Overall: The kernel parameters are valid and match Talos Performance Tuning documentation. The kernel config confirms all required options are built-in (CONFIG_CPU_FREQ_GOV_PERFORMANCE=y, CONFIG_X86_AMD_PSTATE=y, CONFIG_INTEL_IDLE=y).

A couple of notes:

intel_idle.max_cstate=0 disables the intel_idle driver entirely, causing the kernel to fall back to acpi_idle, which also has its own C-states. For complete C-state control, processor.max_cstate=0 would also be needed. This is consistent with the Talos docs (which only mention intel_idle.max_cstate=0), but worth being aware of.
Minor: Trailing whitespace after ;; in the initramfs|kernel case block (line 51 in the diff).

nbykov0 · Feb 11, 2026

I'm investigating the best and most compatible options.

nbykov0 marked this pull request as ready for review January 21, 2026 14:00

nbykov0 requested review from kvaps and lllamnyp as code owners January 21, 2026 14:00

dosubot bot added the size:M This PR changes 30-99 lines, ignoring generated files. label Jan 21, 2026

nbykov0 self-assigned this Jan 21, 2026

dosubot bot added the enhancement New feature or request label Jan 21, 2026

gemini-code-assist bot reviewed Jan 21, 2026

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packages/core/talos/hack/gen-profiles.sh Outdated Show resolved Hide resolved

nbykov0 marked this pull request as draft January 22, 2026 18:36

nbykov0 force-pushed the talos-cpu-freq-scaling branch from b9ecd08 to 1b3aadb Compare February 6, 2026 13:54

[talos] Set cpu frequency scheduler to performance

357887e

Signed-off-by: nbykov0 <166552198+nbykov0@users.noreply.github.com>

nbykov0 force-pushed the talos-cpu-freq-scaling branch from 1b3aadb to 357887e Compare February 6, 2026 14:00

nbykov0 marked this pull request as ready for review February 6, 2026 19:07

nbykov0 requested review from androndo and lexfrei as code owners February 6, 2026 19:07

lexfrei previously requested changes Feb 6, 2026

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lexfrei reviewed Feb 6, 2026

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kvaps requested a review from IvanHunters as a code owner February 10, 2026 15:58

nbykov0 marked this pull request as draft February 11, 2026 07:43

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[talos] Set cpu frequency scheduler to performance#1898

[talos] Set cpu frequency scheduler to performance#1898
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