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Maintaining DAMON (https://damonitor.github.io). All opinions are my own.
sj

sj

Edited 6 months ago
I will be in Tokyo next week. I will have four sessions on OSSummit and LPC. I also reserved the full week for potential in-person and/or virtual DAMON beer/coffee/tea chats [1]. Even if you don't have a topic for DAMON, if you don't mind shaking my hand, please feel free to reach out to me and say hello :)

[1] https://lore.kernel.org/20251205195509.76051-1-sj@kernel.org

#linux #kernel #damon #ossummit #lpc #linux_plumbers
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gregkh

Greg K-H

The last 5.4.y kernel release has now happened: https://lore.kernel.org/all/2025120319-blip-grime-93e8@gregkh/

Please don't use this branch anymore, it's really old, and pretty obsolete, and has over 1500 unfixed CVEs in it:
https://lore.kernel.org/all/2025120358-skating-outage-7c61@gregkh/

And if you are stuck with that kernel version for some reason, go ask your vendor to fix those 1500+ CVEs, otherwise you are paying for support that doesn't actually do anything for you...
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kernellogger@hachyderm.io

Thorsten Leemhuis (acct. 1/4)

6.18.y is now officially a longterm kernel series, as can be seen here:

https://www.kernel.org/category/releases.html

Projected EOL is Dec, 2027 (two years from now) – just like the 6.1.y series. All the other series as of now are scheduled for EOL in about one year from now – and 5.4.y just was EOLed, as planned (see https://social.kernel.org/objects/da258e20-22b9-4805-a9e5-5a506eb2bf91 and https://git.kernel.org/pub/scm/docs/kernel/website.git/commit/?id=0f52d79a5053091c95a269ff6fddbece27ea1d64 ).

Note, the kernel.org front page for the next ~two months (e.g. until 6.19 is out) will keep listing 6.18.y as latest stable series, as it might break peoples scripts to call it longterm there:

https://git.kernel.org/pub/scm/docs/kernel/website.git/commit/?id=b9ea3472ee1d973f4c27d075c7e4445afa7ade89

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KernelRecipes@fosstodon.org

Kernel Recipes

Heya, Heya!

Before the presents land under the Christmas tree, we’re super happy and honored to reveal the name of our godfather for the 2026 edition: @corbet.

Huge thanks to him for giving us a bit of his time — we know how precious it is.

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sj

sj

I was unable to take time on DAMON cpus/write-only monitoring extension project nowadays, while I privately receiving more interests and test results. Hence trying to take more time on it, and shared a rough plan for clarifying expected timelines: https://lore.kernel.org/20251128193947.80866-1-sj@kernel.org

The plan is also available on the blog: https://damonitor.github.io/posts/damon_cpus_write_monitoring_rfc_v3_plan/

#linux #kernel #damon #cpus-only #write-only #development_plan
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sj

sj

Reply to @vbabka@mastodon.social
@vbabka Yes, I remember that. Nevertheless I was unable to "confidently" say it, since someone who has no good way to check the fact might think I'm lying. That's why I'm happy with this great integration work :D. Anyway, appreciate all people who made this availableSUSE, including you!
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sj

@vbabka Glad to be able to confidently and proudly say CONFIG_DAMON is enabled on the one of best Linux distros, OpenSUSE https://oracle.github.io/kconfigs/?config=UTS_RELEASE&config=DAMON

#linux #kernel #damon #opensuse #oracle_kconfigs

RE: https://mastodon.social/@vbabka/115582339822470165
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sj

sj

> this gives me a motivation for unifying the capacity and bandwidth expansion solutions. I may share a thought soon on the mailing list.

Just posted a rough and early idea about how to provide a holistic tiered memory management for both capacity (or, latency) and bandwidth: https://lore.kernel.org/all/20251114014255.72884-1-sj@kernel.org/

FYI, I got the idea from a chat with a dynamic interleaving developer at Micron, as I also noted on the mail, and HMSDK talk gave me more motivation to develop it.

#linux #kernel #damon #tpp #bandwidth

RE: https://social.kernel.org/objects/75d16f79-f7b5-40f5-8c41-14ec3274fac1
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sj

sj

Edited 6 months ago
SK Hynix HMSDK presentation video at OSSummit Korea is now available: https://sched.co/2913n

As a part of the talk, HMSDK's CXL memory capacity expansion, which utilizes DAMON internally, is also introduced. It provides detailed explanation of design, their test setup, results, and even a multi-threads based tuning tip. Especially the evaluation using an LLM workload is impressive to me.

Also, this gives me a motivation for unifying the capacity and bandwidth expansion solutions. I may share a thought soon on the mailing list.

#linux #kernel #damon #hmsdk #ossummit_korea
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linuxplumbersconf@mastodon.social

Linux Plumbers Conference

Japan visa applications need to be in by 17 November at the latest: https://lpc.events/blog/current/index.php/2025/10/29/japan-visas-need-a-longer-processing-time/

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sj

Abstracts of my LPC sessions are available now.

- "Page-level and Fleet-wide Data Access Monitoring for Meta", Refereed tack, Friday afternoon: https://lpc.events/event/19/contributions/2075/
- "Actionable Data Access Monitoring Output Data and Format", Linux System Monitoring and Observability MC, Thursday morning: https://lpc.events/event/19/contributions/2059/
- "DAMON-based Pages Migration for {C,G,X}PU [un]attached NUMA nodes", Device and Specific Purpose Memory MC, Thursday morning: https://lpc.events/event/19/contributions/2066/

#linuxplumbers #linux #kernel #damon

RE: https://social.kernel.org/objects/7f6edd64-5fbf-4a5d-b192-d00894198ca0
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sj

Reply to @sj
And today I started a new position at the kernel team of crusoe.ai.
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kernellogger@hachyderm.io

Thorsten Leemhuis (acct. 1/4)

Edited 7 months ago

TWIMC, the "Linus opposes Link: tags with links to the patch submission" is saga over, as Linus wrote:

""[…] I do think that at least if people use the different domain, I won't complain.

I'm still not convinced it's a great idea, but at least it means that the "this is the source of the commit" is clearly separate from the "this is actual background". […]""

https://lore.kernel.org/all/CAHk-%3Dwj5MATvT-FR8qNpXuuBGiJdjY1kRfhtzuyBSpTKR%2B%3DVtw@mail.gmail.com/

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sj

sj

Today was my last day at Meta. It was great to be connected and work with the awesome and nice people. I believe nothing is really being ended though, since we will keep being connected and work together on upstream open source communities.
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sj

Reply to @gregkh
Edited 7 months ago
@gregkh Inspired by the results, I bought a ~$320 mini PC from Aamzon and ran kcbench.

```
Processor: AMD Ryzen 7 6800H with Radeon Graphics [16 threads]
Cpufreq; Memory: powersave [amd-pstate-epp]; 27841 MiB
Linux running: 6.12.48+deb13-amd64 [x86_64]
Compiler: gcc (Debian 14.2.0-19) 14.2.0
Linux compiled: 6.17.0 [.../.cache/kcbench/linux-6.17]
Config; Environment: defconfig; CCACHE_DISABLE="1"
Build command: make vmlinux
Filling caches: This might take a while... Done
Run 1 (-j 16): 161.38 seconds / 22.31 kernels/hour [P:1440%, 134 maj. pagefaults]
Run 2 (-j 16): 162.53 seconds / 22.15 kernels/hour [P:1441%, 140 maj. pagefaults]
Run 3 (-j 19): 172.87 seconds / 20.82 kernels/hour [P:1366%, 266 maj. pagefaults]
Run 4 (-j 19): 164.76 seconds / 21.85 kernels/hour [P:1446%, 258 maj. pagefaults]
Run 5 (-j 8): 190.83 seconds / 18.86 kernels/hour [P:742%, 49 maj. pagefaults]
Run 6 (-j 8): 190.21 seconds / 18.93 kernels/hour [P:743%, 55 maj. pagefaults]
Run 7 (-j 11): 178.62 seconds / 20.15 kernels/hour [P:1011%, 96 maj. pagefaults]
Run 8 (-j 11): 185.62 seconds / 19.39 kernels/hour [P:975%, 126 maj. pagefaults]
```

Seems not a bad option for a hobbyist kernel hacker! Thanks @kernellogger for making kcbench!
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sj

And I'd like to appreciate @linuxfoundation for supporting the trip for Kangrejos. It was hugely helpful!

#kangrejos #linuxfoundation

RE: https://social.kernel.org/objects/f9ebce6d-3948-497b-834a-0bf1758fc07a
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paulmckrcu

Paul E. McKenney

And my Kernel Recipes talk is now available: https://youtu.be/qYPCL1KGdQA

A big "Thank you!" to everyone involved!
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sj

And here is the video of mine: https://youtu.be/lvRuBxli_yU?si=iybBRdrINHydfSjb

Thank you @KernelRecipes !

#linux #kernel #damon #kr2025

RE: https://fosstodon.org/@KernelRecipes/115335044360364512
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KernelRecipes@fosstodon.org

Kernel Recipes

After letting them simmer for a few days, they’re finally ready! The videos are now online and waiting for you to watch. You’ll also find the presentation slides we’ve received so far.

Enjoy!

Slides and videos: https://kernel-recipes.org/en/2025/schedule/

Watch all the videos : https://www.youtube.com/playlist?list=PLQ8PmP_dnN7JIsjWbFPeRdze4MQHHkIm8

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sj

sj

Linux kernel memory mangement subsystem changes [1] for 6.18-rc1, which includes most new features, are merged into the mainline.

So many interesting works in there. To DAMON maintainer's humble view, two brilliant changes stand out.

1. virtual address space page level monitoring support [2], which was developed by Yueyang Pan (Meta).
2. Support of 32-bit ARM with LPAE [3], which was collaboratively developed by I and Huawei people (Quanmin Yan and Ze Zuo). Most changes are authored by me, but the real workers were Quanmin and Ze from Huawei.

As always I highly recommend everyone to read Andrew's great summary [1] of the whole changes!

[1] https://lore.kernel.org/20251001190218.f33f695b869696c2df9e841d@linux-foundation.org
[2] https://lkml.kernel.org/r/cover.1754135312.git.pyyjason@gmail.com
[3] https://lore.kernel.org/https://lkml.kernel.org/r/20250828171242.59810-1-sj@kernel.org

#linux #kernel #mm #damon #6.18-rc1 #pull_request
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