From alexandru.lazarev at gmail.com  Wed Apr  9 07:30:07 2025
From: alexandru.lazarev at gmail.com (Alexandru Lazarev)
Date: Wed, 9 Apr 2025 14:30:07 +0300
Subject: Performance Degradation with rsync in container or cgroupv2 with
 MEM limit
In-Reply-To: <CAL93h0FMRcegKJ3VNALkEs_y_+9Me6p6CLc-nGyHv0eHurajcA@mail.gmail.com>
References: <CAL93h0HkF_f8tgTTqKppNpOX=QnsWQA8F9XFAsDD3OF4mh1UzQ@mail.gmail.com>
 <2025032630-unsterile-pamperer-537c@gregkh>
 <CAL93h0FMRcegKJ3VNALkEs_y_+9Me6p6CLc-nGyHv0eHurajcA@mail.gmail.com>
Message-ID: <CAL93h0HDfuZHc1TTu5yGy+X0gMy5QjtL10-Ayp6dykPzcvLnAg@mail.gmail.com>

I'll answer my own question here:
Looks like it is a bug in Oracle Linux (OL) 9.2 RHCK Kernel
"kernel-5.14.0-284.11.1" (see table:
https://docs.oracle.com/en/operating-systems/oracle-linux/9/boot/oracle_linux9_kernel_version_matrix.html)

Switching to UEK Kernel of the same OL version (9.2) fixed the issue,
but UEK is not supported by some SW (e.g. Vertica DB), so that I've
tried RHCK Kernels update: only Kernel and dependencies from OL9.4
(kernel-5.14.0-427) and OL9.5 (kernel-5.14.0-503.11.1) - both fixed
the issue, with remark: RHCK update using one from OL9.5 is suspected
to have some HW compatibility issues (under investigation).
Some more details discussed here:
https://www.linuxquestions.org/questions/linux-containers-122/performance-degradation-with-rsync-in-container-or-cgroupv2-with-mem-limit-on-oracle-linux-9-2-rhck-5-14-vs-uek-5-15-a-4175749063/

On Wed, Mar 26, 2025 at 4:10?PM Alexandru Lazarev
<alexandru.lazarev at gmail.com> wrote:
>
> hi Greg,
> Thx for Your feedback - I would appreciate any feedback.
>
> I'am not paying for it - I am doing some tests on a given platform.
> Kernel is RHCK.
> I posted this question-issue here because maybe it is some generic
> kernel issue (I saw several of unanswered threads on various platforms
> of rsync degradation in containers) amnd someone can suggest to me
> right directions, OR..
> I know here in mail list are some people from Red Hat and Oracle which
> usually provide their valuable answered, so I am still keep my hopness
> on finding some ideas on this issue
>
> On Wed, Mar 26, 2025 at 4:00?PM Greg KH <greg at kroah.com> wrote:
> >
> > On Wed, Mar 26, 2025 at 02:11:41PM +0200, Alexandru Lazarev wrote:
> > > Hi everyone,
> > > I'm experiencing a significant performance degradation when using
> > > "rsync" to copy files over the network from within a container or
> > > cgroup with memory limits on Oracle Linux 9.2. The issue occurs with
> > > the Red Hat Compatible Kernel (RHCK) 5.14.0-284.11.1.el9_2.x86_64 but
> > > not with the Unbreakable Enterprise Kernel (UEK)
> > > 5.15.0-101.103.2.1.el9uek.x86_64.
> >
> > <snip>
> >
> > As you are paying for Oracle support for these kernels, please contact
> > them to take advantage of that support.  They are the only ones that can
> > help you out here as no one in the community has any idea of what is in
> > these kernels at all, sorry.
> >
> > good luck!
> >
> > greg k-h


From a.nasrolahi01 at gmail.com  Mon Apr 21 10:59:45 2025
From: a.nasrolahi01 at gmail.com (Ali Nasrolahi)
Date: Mon, 21 Apr 2025 18:29:45 +0330
Subject: Documentation for Regmap API?
Message-ID: <54visxfcp6w2vaktyezwxbvsaqpeocjhnzwyt7jw4gumnyz3fu@iz6vh7yabm7a>

Hi,

I've been exploring the Regmap API and
was wondering if there?s a dedicated documentation page
that provides an overview or explanation of the API itself.

So far, I?ve looked into the following:

1. https://docs.kernel.org/driver-api/index.html
2. The Documentation/ directory in both the mainline and linux-next trees.
3. The regmap tree mentioned in the MAINTAINERS file:
---
   REGISTER MAP ABSTRACTION
   M:  Mark Brown <broonie at kernel.org>
   L:  linux-kernel at vger.kernel.org
   S:  Supported
   T:  git git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git
   F:  Documentation/devicetree/bindings/regmap/
   F:  drivers/base/regmap/
   F:  include/linux/regmap.h
---

Despite checking these locations,
I couldn?t find a dedicated document explaining the Regmap API in detail.

1. Is there any such documentation available that I might have missed?

2. If not, I?d be happy to contribute and help write one.
Should I bring this up on the linux-doc mailing list for further guidance on how to proceed?

Any pointers or suggestions would be greatly appreciated.

Thanks a lot,
Ali



From richard_siegfried at systemli.org  Mon Apr 21 18:16:17 2025
From: richard_siegfried at systemli.org (Richard)
Date: Tue, 22 Apr 2025 00:16:17 +0200
Subject: Documentation for Regmap API?
In-Reply-To: <54visxfcp6w2vaktyezwxbvsaqpeocjhnzwyt7jw4gumnyz3fu@iz6vh7yabm7a>
References: <54visxfcp6w2vaktyezwxbvsaqpeocjhnzwyt7jw4gumnyz3fu@iz6vh7yabm7a>
Message-ID: <62c1ca64-afa1-401c-abb6-bf6787e60913@systemli.org>

Hi,

The book "Linux Driver Development" by John Madieu has a good 
explanation of how to use the Regmap API

-- Richard

On 21/04/2025 16:59, Ali Nasrolahi wrote:
> Hi,
> 
> I've been exploring the Regmap API and
> was wondering if there?s a dedicated documentation page
> that provides an overview or explanation of the API itself.
> 
> So far, I?ve looked into the following:
> 
> 1. https://docs.kernel.org/driver-api/index.html
> 2. The Documentation/ directory in both the mainline and linux-next trees.
> 3. The regmap tree mentioned in the MAINTAINERS file:
> ---
>     REGISTER MAP ABSTRACTION
>     M:  Mark Brown <broonie at kernel.org>
>     L:  linux-kernel at vger.kernel.org
>     S:  Supported
>     T:  git git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git
>     F:  Documentation/devicetree/bindings/regmap/
>     F:  drivers/base/regmap/
>     F:  include/linux/regmap.h
> ---
> 
> Despite checking these locations,
> I couldn?t find a dedicated document explaining the Regmap API in detail.
> 
> 1. Is there any such documentation available that I might have missed?
> 
> 2. If not, I?d be happy to contribute and help write one.
> Should I bring this up on the linux-doc mailing list for further guidance on how to proceed?
> 
> Any pointers or suggestions would be greatly appreciated.
> 
> Thanks a lot,
> Ali
> 
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies



From richard_siegfried at systemli.org  Mon Apr 21 18:19:15 2025
From: richard_siegfried at systemli.org (Richard)
Date: Tue, 22 Apr 2025 00:19:15 +0200
Subject: Becoming the next DCCP maintainer?
Message-ID: <9b3a6955-2175-4671-af01-f0a67f4f7746@systemli.org>

Hi,

I do have an interest in DCCP staying in the Linux Kernel since I'm 
using it for my PhD thesis research and also one other possible research 
project in the future. I'm thinking about offering to maintain the DCCP 
stack in the Linux Kernel and have some questions regarding it:

1. Is it still possible? Or am I too late already?
2. How much work would it be? Is it something that can be done in 
parallel to a regular job?


Thanks,
-- Richard


From racz.zoli at gmail.com  Thu Apr 24 15:44:14 2025
From: racz.zoli at gmail.com (Racz Zoli)
Date: Thu, 24 Apr 2025 22:44:14 +0300
Subject: Looking for advice on getting started with kernel development
 professionally
Message-ID: <CANoGd8=bWdLh+0vj2siNEK9ukWKp1YR74zdvLGbM6t9_0CG50A@mail.gmail.com>

Hi all,

I hope it's okay to ask this here. I understand this list is mostly
for learning and discussion. I've been working on kernel-related
projects in my spare time, including an experimental filesystem, a
block level incremental backup utility, btrfs-progs and currently I`m
working on a multithreaded disk usage analyzer like "du" but written
from scratch.

I'm really interested in contributing to the Linux kernel
professionally and while I have over 15 years of programming
experience in different areas - was wondering if anyone had advice or
knew of any opportunities - internships, contract work, or mentoring
programs.

Totally understand if this isn't the right place to ask, but I'd be
grateful for any tips or redirections.

Thank you,
Zoltan Racz.


From tanure at linux.com  Thu Apr 24 15:56:01 2025
From: tanure at linux.com (Lucas Tanure)
Date: Thu, 24 Apr 2025 16:56:01 -0300
Subject: Looking for advice on getting started with kernel development
 professionally
In-Reply-To: <CANoGd8=bWdLh+0vj2siNEK9ukWKp1YR74zdvLGbM6t9_0CG50A@mail.gmail.com>
References: <CANoGd8=bWdLh+0vj2siNEK9ukWKp1YR74zdvLGbM6t9_0CG50A@mail.gmail.com>
Message-ID: <CAJX_Q+0bOyxTh9n8bLy2-j+LweU1Qa_+oHHgakCscdcJFyQNiA@mail.gmail.com>

On Thu, Apr 24, 2025 at 4:47?PM Racz Zoli <racz.zoli at gmail.com> wrote:
>
> Hi all,
>
> I hope it's okay to ask this here. I understand this list is mostly
> for learning and discussion. I've been working on kernel-related
> projects in my spare time, including an experimental filesystem, a
> block level incremental backup utility, btrfs-progs and currently I`m
> working on a multithreaded disk usage analyzer like "du" but written
> from scratch.
>
> I'm really interested in contributing to the Linux kernel
> professionally and while I have over 15 years of programming
> experience in different areas - was wondering if anyone had advice or
> knew of any opportunities - internships, contract work, or mentoring
> programs.
>
Identify something in the kernel that can be improved, fixed, or
documented. Submit some patches and demonstrate to your future
employer that you have experience working with upstream projects and
the community.
Read: https://kernelnewbies.org/Outreachyfirstpatch

And when someone asks for your upstream experience, you can send this
grep on the kernel commits:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/?qt=grep&q="YOUR
NAME OR EMAIL"
Like mine:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/?qt=grep&q=tanure

This is just the first step.

Best of Luck
Lucas Tanure

> Totally understand if this isn't the right place to ask, but I'd be
> grateful for any tips or redirections.
>
> Thank you,
> Zoltan Racz.
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies


From a.nasrolahi01 at gmail.com  Sun Apr 27 13:25:50 2025
From: a.nasrolahi01 at gmail.com (Ali Nasrolahi)
Date: Sun, 27 Apr 2025 20:55:50 +0330
Subject: Documentation for Regmap API?
In-Reply-To: <62c1ca64-afa1-401c-abb6-bf6787e60913@systemli.org>
References: <54visxfcp6w2vaktyezwxbvsaqpeocjhnzwyt7jw4gumnyz3fu@iz6vh7yabm7a>
 <62c1ca64-afa1-401c-abb6-bf6787e60913@systemli.org>
Message-ID: <3lk7rvcsa5iqegijf2wywhlnyqqcrecd3quidmq3wjdzr4wh2m@qm3mdlxu3vvp>

Thank you for your response, Richard.

Yes, I've read the book; however, I was hoping to have an up-to-date in-tree
documentation for it.  That's the main reason why I proposed my help to write one.

-- Ali

On 25/04/22 12:16AM, Richard wrote:
> Hi,
> 
> The book "Linux Driver Development" by John Madieu has a good explanation of
> how to use the Regmap API
> 
> -- Richard
> 
> On 21/04/2025 16:59, Ali Nasrolahi wrote:
> > Hi,
> > 
> > I've been exploring the Regmap API and
> > was wondering if there?s a dedicated documentation page
> > that provides an overview or explanation of the API itself.
> > 
> > So far, I?ve looked into the following:
> > 
> > 1. https://docs.kernel.org/driver-api/index.html
> > 2. The Documentation/ directory in both the mainline and linux-next trees.
> > 3. The regmap tree mentioned in the MAINTAINERS file:
> > ---
> >     REGISTER MAP ABSTRACTION
> >     M:  Mark Brown <broonie at kernel.org>
> >     L:  linux-kernel at vger.kernel.org
> >     S:  Supported
> >     T:  git git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git
> >     F:  Documentation/devicetree/bindings/regmap/
> >     F:  drivers/base/regmap/
> >     F:  include/linux/regmap.h
> > ---
> > 
> > Despite checking these locations,
> > I couldn?t find a dedicated document explaining the Regmap API in detail.
> > 
> > 1. Is there any such documentation available that I might have missed?
> > 
> > 2. If not, I?d be happy to contribute and help write one.
> > Should I bring this up on the linux-doc mailing list for further guidance on how to proceed?
> > 
> > Any pointers or suggestions would be greatly appreciated.
> > 
> > Thanks a lot,
> > Ali
> > 
> > 
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> 
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies


From richard_siegfried at systemli.org  Sun Apr 27 20:12:18 2025
From: richard_siegfried at systemli.org (Richard)
Date: Mon, 28 Apr 2025 02:12:18 +0200
Subject: TCP pacing rate calculated even when TCP pacing is not used
Message-ID: <d4b15758-4b26-42f4-ab29-c11f96393b72@systemli.org>

Hi,

I noticed with the output of ss -ti (example):

> ESTAB                          0                               0                                                          YYYYYY:40482                                                     XXXXXX:imaps                          
>          cubic wscale:3,7 rto:228 rtt:27.02/9.695 ato:40 mss:1400 pmtu:1500 rcvmss:1400 advmss:1448 cwnd:10 bytes_sent:1132 bytes_acked:1133 bytes_received:53005 segs_out:41 segs_in:57 data_segs_out:10 data_segs_in:49 send 4.15Mbps lastsnd:66520 lastrcv:66496 lastack:66496 pacing_rate 8.29Mbps delivery_rate 594kbps delivered:11 app_limited busy:288ms rcv_rtt:17.25 rcv_space:25313 rcv_ssthresh:128820 minrtt:18.859 rcv_ooopack:1 snd_wnd:6136 rcv_wnd:128896

that for every tcp socket, the kernel calculates and maintains a 
*pacing_rate* even if TCP pacing is turned off (which is the default). I 
could observe this on several servers and many different linux versions 
too.

Why does TCP do this? Isn't that a waste of memory and processing time 
to mantain when the default is not to use it?

Thanks,
-- Richard


From alison.schofield at intel.com  Mon Apr 28 17:02:32 2025
From: alison.schofield at intel.com (Alison Schofield)
Date: Mon, 28 Apr 2025 14:02:32 -0700
Subject: Looking for advice on getting started with kernel development
 professionally
In-Reply-To: <CANoGd8=bWdLh+0vj2siNEK9ukWKp1YR74zdvLGbM6t9_0CG50A@mail.gmail.com>
References: <CANoGd8=bWdLh+0vj2siNEK9ukWKp1YR74zdvLGbM6t9_0CG50A@mail.gmail.com>
Message-ID: <aA_s6EafNAWOA9ai@aschofie-mobl2.lan>

On Thu, Apr 24, 2025 at 10:44:14PM +0300, Racz Zoli wrote:
> Hi all,
> 
> I hope it's okay to ask this here. I understand this list is mostly
> for learning and discussion. I've been working on kernel-related
> projects in my spare time, including an experimental filesystem, a
> block level incremental backup utility, btrfs-progs and currently I`m
> working on a multithreaded disk usage analyzer like "du" but written
> from scratch.
> 
> I'm really interested in contributing to the Linux kernel
> professionally and while I have over 15 years of programming
> experience in different areas - was wondering if anyone had advice or
> knew of any opportunities - internships, contract work, or mentoring
> programs.
> 
> Totally understand if this isn't the right place to ask, but I'd be
> grateful for any tips or redirections.

Hi Zoltan,

If you haven't already, engage with the communities you are interested in
thought their mailing list - ie https://lore.kernel.org/linux-btrfs/
By engage, I mean follow their list, ask questions, review patches.
Even if you are a newbie, there are clarifying questions that you can
pose that others will appreciate. The point is, that before you start
asking for your contibutions to be reviewed and merged, become a known
quantity on the list. Support others. Another responder mentioned the
query that finds your tags - note we have tags for Tested-by, and 
Reviewed-by, in addition to Signed-off-by:  and all are valued.

I think this program is an option for and will get you a very 
structured start to kernel submission - https://wiki.linuxfoundation.org/lkmp

Good luck!
Alison




> 
> Thank you,
> Zoltan Racz.
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies