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

Greg K-H

Here's a link to the slides for my "Why are there so many kernel CVEs?" talk I gave at OSS China yesterday:
https://kccncossaidevchn2024.sched.com/event/ed2b39a9a0cdfc1df18de67ce0c2f6be

Link to git repo for the slides if the schedule site acts odd for you:
https://git.sr.ht/~gregkh/presentation-security

It was fun, and will be the "set up" for my Kernel Recipes talk in Paris in a few weeks (only 3 conferences to go between now and then, travel is back in full swing.)
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kernellogger@fosstodon.org

Thorsten Leemhuis (acct. 1/4)

Registration for @linuxplumbersconf reopened

'"This year there was a huge demand to attend Conference in person and at last we were able to add more places and reopen the registration."'

https://lpc.events/blog/current/index.php/2024/08/16/registration-is-now-reopened/

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sj

GitHub repos for non-kernel parts of DAMON project including 'damo', 'damon-tests' and 'damoos' will be moved from 'awslabs' to 'damonitor', by 2024-09-05: https://lore.kernel.org/20240813232158.83903-1-sj@kernel.org

#linux #kernel #damon #damo #damon-tests #damoos
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kees@fosstodon.org

Kees Cook tux

Building on the excellent codetag/alloc_tag infrastructure recently added to Linux, I've got an initial implementation of per-call-site kmalloc cache isolation:
https://lore.kernel.org/lkml/20240809072532.work.266-kees@kernel.org/

It's sure to give @vbabka nightmares and frustrate shared-cache use-after-free exploits. 😁

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Edited 3 months ago
VLDB paper about Aurora Serverless V2, which reveals their usage of DAMON on the product, is now available: https://www.amazon.science/publications/resource-management-in-aurora-serverless

#linux #kernel #damon #aurora_serverless_v2
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sj

Edited 3 months ago
We are looking for DAMON recipes that I could share on upcoming OSSummit EU, or (hopefully) DAMON microconf at LPC'25: https://lore.kernel.org/20240724222119.58477-1-sj@kernel.org

#linux #kernel #damon #ossummit #linuxplumbers
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Edited 3 months ago
Memory Management subsystem pull request for Linux v6.11-rc1 is posted[1] with DAMON changes for CXL memory tiering[2], documentation[3] of a mailing tool for newcomers (HacKerMaiL), and minor fixups.

[1] https://lore.kernel.org/20240721145415.fbeb01a853962ef91334f3d1@linux-foundation.org
[2] https://lore.kernel.org/20240614030010.751-1-honggyu.kim@sk.com
[3] https://lore.kernel.org/20240621163626.74815-1-sj@kernel.org

#linux #kernel #damon #hkml
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Reply to @sj

@vbabka And, the fix[1] is pushed. I confirmed it works as below:

$ cat slab_pixel
11111 11
11 11 11
11 11111

11111111
      11
      11

11111111
11 11
11111111

11111111
11 11 11
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$ ./pixels_to_access_config.py slab_pixel $((100* 1024*1024)) 250 slab.cfg
$ sudo ../damo/damo record "./masim ./slab.cfg"
$ sudo ../damo/damo report heatmap --output slab.png

[1] https://github.com/awslabs/damo/commit/7d6fd42371cc6a1611da72fde6076ca7b5ad1b37

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Reply to @vbabka
@vbabka Thank you for clarifying. I think that should be the case that I explained. I'll update the heatmap plot target selection or do something else to make the reproduction smoother. The --address_range option should work as a workaround until the update is landed.
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Reply to @sj
@vbabka Yet another workaround is using `damo report holistic` instead. It will plot the heatmap for three regions at once, like https://github.com/awslabs/damo/blob/v2.4.3/USAGE.md#holistic .
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Reply to @vbabka
@vbabka I guess you were using `damo report heats --heatmap` or `damo report heatmap` for virtual address space accesses monitoring? If so, `--address_range` option might need to be used.

In detail, in case of virtual address spaces monitoring, there are two huge address gaps between stack, mmap()-ed regions, and heat. Hence drawing heatmap for entire mapped regions results in only black image. Hence `damo` finds up to three biggest contiguous adress ranges (for heap, stack, and mmap()-ed regions) in the record that consistently shown some accesses. Then, it plots heatmap for biggest region. In some cases, real accesses are made in mmap()-ed regions but heat area has larger mapped regions, so `damo` ends up plotting heatmap for the heat area that not really actively accessed. In the case, you show only black image. For this case, `damo report heatmap --guide` shows the three regions that `damo` found. You can find what address range you need to plot the heatmap, and set it using `--address_range` option.

We were planning to update the default plot target address range from biggest region to regions having most heats in near future, but it has not prioritized so far. Now it has an issue: https://github.com/awslabs/damo/issues/106

Please let me know if this is not the case.
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Reply to @corbet
@corbet Thanks for headsup. I was more curious about the source tree. Seems only a couple of shortened URLs are in the source tree, fortunately.

```
$ git grep goo.gl
Documentation/filesystems/9p.rst: http://goo.gl/3WPDg
net/ipv4/Kconfig: delay gradients." In Networking 2011. Preprint: http://goo.gl/No3vdg
```

I may post patches later, unless others do.
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DAMON topic for Linux Kernel Memory Management Microconference at LPC'24, titled "DAMON: Long-term Plans for Kernel That {Just Works,Extensible}" has been accepted[1].

[1] https://lpc.events/event/18/contributions/1768/

#linux #kernel #damon
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DAMON user-space tool, damo, v2.4.3[1] is now available. The version supports showing access pattern, memory footprints, and hotspot functions all at once on live. An animated-gif for that is available[2].

[1] https://github.com/awslabs/damo/blob/v2.4.3/release_note
[2] https://github.com/awslabs/damo/blob/v2.4.3/README.md#holistic-memory-usage-monitoring

#linux #kernel #damon #damo
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I created a logo for DAMON using DAMON, just for fun.

You could also create some for yourself. For detailed instructions: https://sjp38.github.io/post/damon_heatmap_logo/

#linux #kernel #damon #damo #masim
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vbabka

Vlastimil Babka

Congrats to my colleague @ggherdov to his first LWN guest article blobcatamused

RE: https://fosstodon.org/@LWN/112768427133634587
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ATC'24 also published two DAMON-citing papers at the same time. The first one[1] proposes a way to improve monitoring accuracy of DAMON, while the second one[2] mentions DAMON can be useful for extensible memory management (mm-ext? ;) ).

[1] Telescope: Telemetry for Gargantuan Memory Footprint Applications, https://www.usenix.org/conference/atc24/presentation/nair
[2] FBMM: Making Memory Management Extensible With Filesystems, https://www.usenix.org/conference/atc24/presentation/tabatabai

#linux #kernel #damon #atc #mm-ext

RE: https://social.kernel.org/objects/92b159a6-48c2-4008-bffd-49c5f783f9ca
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Edited 4 months ago
A couple of OSDI'24 papers[1,2] for memory tiering that references and exploring DAMON as a part of them are available now.

[1] https://www.usenix.org/conference/osdi24/presentation/xiang
[2] https://www.usenix.org/conference/osdi24/presentation/zhong-yuhong

#linux #kernel #damon #osdi #cxl
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DAMO v2.4.2 [1] is out. It makes the report more holistic with hotspot functions in addition to the heatmap, wss, and memory footprints. Refer to USAGE[2] for details and an example report.

[1] https://github.com/awslabs/damo/blob/v2.4.2/release_note#L4
[2] https://github.com/awslabs/damo/blob/v2.4.2/USAGE.md#holistic

#linux #kernel #damon #damo
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Edited 4 months ago
I just posted DAMON quaterly news letter for 2024-Q2.

Highlights of highlights: DAMON gained a feature for CXL-based tiered memory management. HacKerMaiL (hkml), a simple mailing tool that DAMON maintainer is developing, made an official commitment to support DAMON community.

https://lore.kernel.org/20240701212244.52288-1-sj@kernel.org

#linux #kernel #damon
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