[en] Add blog post on tuning linux kernel parameters for swap

[ajaysundark]

Description

feat: Add blog post on Linux Swap Tuning for Kubernetes

This PR introduces a blog post on optimizing Linux swap utilization within Kubernetes environments.

Abstract:

This blog post will provide a comprehensive guide to understanding and tuning critical Linux kernel parameters related to swap, including min_free_kbytes, watermark_scale_factor and swappiness. It will explore how these parameters directly influence Kubernetes workload performance, memory management, and crucial eviction mechanisms. We will present detailed test results showcasing the impact of various configurations, highlight the significant risks associated with incorrect swap tuning (such as inadvertently disabling evictions or impacting OOM Killer behavior), and share our findings on achieving optimal settings for stable and high-performing Kubernetes clusters.

Issue

KEP: kubernetes/enhancements#2400
Closes: #51153

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[lmktfy]

Great. Would you like to buddy with another blog article author @ajaysundark ?

[ajaysundark]

Thanks @lmktfy . From the blog guidelines, I understand the buddy assists with draft review and feedback on the article. Does it make sense for me to seek buddy assistance / review here after the initial draft is ready?

[iholder101]

/cc

[aibarbetta]

Hi @HirazawaUi @ajaysundark 👋 this is Agus from the v1.34 Communications Team!

@HirazawaUi as author of #51529, I'd like you to be a writing buddy for @ajaysundark on this PR.

Please:

• Review this PR, paying attention to the guidelines and review hints
• Update your own PR based on any best practices you identify that should be applied
• Remember to be compassionate with your fellow article author

[aibarbetta]

/sig release

[dipesh-rawat]

Hi 👋, v1.34 Communications Team here again!

Since the KEP didn’t meet the code freeze deadline and has been removed from the v1.34 milestone (based on kubernetes/enhancements#2400 (comment)), this KEP won’t be part of the upcoming release.

@ajaysundark, to keep things clear and streamlined, I recommend closing this PR for now. We’d definitely encourage revisiting it in a future cycle when the KEP is back on track.

Looping in @aibarbetta (v1.34 Comms lead) to keep the team aligned. Thanks so much!

[ajaysundark]

Exception request for KEP-2400 approved: https://groups.google.com/g/kubernetes-sig-node/c/IGF6v3G9lds, and Node Memory Swap support is continued to be tracked for 1.34 GA.

[dipesh-rawat]

Exception request for KEP-2400 approved: https://groups.google.com/g/kubernetes-sig-node/c/IGF6v3G9lds, and Node Memory Swap support is continued to be tracked for 1.34 GA.

@ajaysundark Thanks for the update! Since the KEP exception request is currently pending final approval from the Release Team, we’re happy to keep this PR open for now. Once it’s approved and the KEP-2400 is added back to the milestone, we can move forward with the blog.

[ajaysundark]

Hi @dipesh-rawat / @aibarbetta - now that NodeSwap feature is tracked for v1.34, could you please include this for 1.34 blog scope too?

[dipesh-rawat]

Hi @ajaysundark 👋, v1.34 Communications Team here again!

Now that exception is sorted for the KEP, this is already being considered for the feature blog for v1.34 release.

Just a friendly reminder that we are approaching the feature blog "Ready for review" deadline: Friday 8th August 2025. We ask you to have the blog in non-draft state, and all write-up to be complete.

If you have any questions or need help, please don't hesitate to reach out to me or any of the Communications Team members. We are here to help you!

[ajaysundark]

Thank you @dipesh-rawat, I'm looking into it. I'll have the draft ready soon, and sync with my buddy review @HirazawaUi .

[dipesh-rawat]

@ajaysundark Please update the PR to merge into main instead of dev.1-34.
The workflow for feature blog posts differs from the one used for upcoming release changes and new features.
You can find the relevant details here.

[ajaysundark]

Thanks @dipesh-rawat , I'll update this PR to target main.

Hi @HirazawaUi - Would you be available to review https://hackmd.io/@ajaysundark/rJEhBDRExl for your thoughts?
If you suggest it could be better at github, I could update the draft here for comments.

[ajaysundark]

Thanks for working on this further.

I'm trying to strike the right balance between giving you your authentic voice as a blog author, but also not taking too many shortcuts with the facts and specifics.

How would you like to move this article forward, given that feedback? I think it's just not quite there for me to merge it right now.

Thanks for your review, sharing many critical details and depths at the draft. I addressed many of your feedback.
One aspect I'm unsure about is on the Windows swap claims we could mention at this blog. Since NodeSwap feature (and the experiments performed as discussed here) is explicitly targeted at Linux nodes, I'm vary of mixing the details. I would prefer to exclude Windows discussion here. Wdyt?

[lmktfy]

One aspect I'm unsure about is on the Windows swap claims we could mention at this blog. Since NodeSwap feature (and the experiments performed as discussed here) is explicitly targeted at Linux nodes, I'm vary of mixing the details. I would prefer to exclude Windows discussion here

If we don't mention Windows nodes, there is a risk of misleading people: they may think that what they read in the article applies to all nodes, regardless of node OS.

One potential way to avoid that: explain that the article is only about swap on Linux nodes.

[ajaysundark]

One aspect I'm unsure about is on the Windows swap claims we could mention at this blog. Since NodeSwap feature (and the experiments performed as discussed here) is explicitly targeted at Linux nodes, I'm vary of mixing the details. I would prefer to exclude Windows discussion here

If we don't mention Windows nodes, there is a risk of misleading people: they may think that what they read in the article applies to all nodes, regardless of node OS.

One potential way to avoid that: explain that the article is only about swap on Linux nodes.

Got it. Thanks, that makes sense. I updated the draft to explicitly state that the post is about Linux nodes, setting the context right from the start. Please take a look.

[ajaysundark]

/cc @SergeyKanzhelev

[SergeyKanzhelev]

lgtm with couple of comments

[ajaysundark]

Hi @lmktfy - Do you have more feedback for me here?

[SergeyKanzhelev]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: aaa4c46926d11a8fa741be2d019facde4b4187ea

[lmktfy]

I propose to tweak the wording just slightly.

[lmktfy]

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 5315dc78c78bc8483a7b9a6a2439bc33b4e71296

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lmktfy, SergeyKanzhelev

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