linux-kernel - Re: [PATCH v2 0/4] Add SWIG Bindings to libcpupower

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Message-ID: <ab9e3727-9978-4a30-8bff-e366fa5defc1@linuxfoundation.org>
Date: Wed, 4 Sep 2024 06:41:14 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: "John B. Wyatt IV" <jwyatt@...hat.com>
Cc: linux-pm@...r.kernel.org, Thomas Renninger <trenn@...e.com>,
 Shuah Khan <shuah@...nel.org>, Linus Torvalds
 <torvalds@...ux-foundation.org>, linux-kernel@...r.kernel.org,
 John Kacur <jkacur@...hat.com>, Tomas Glozar <tglozar@...hat.com>,
 Arnaldo Melo <acme@...hat.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 "John B. Wyatt IV" <sageofredondo@...il.com>,
 Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v2 0/4] Add SWIG Bindings to libcpupower

On 8/27/24 00:24, John B. Wyatt IV wrote:
> SWIG is a tool packaged in Fedora and other distros that can generate
> bindings from C and C++ code for several languages including Python,
> Perl, and Go. Providing bindings for scripting languages is a common feature
> to make use of libraries more accessible to more users and programs. My team
> specifically wants to expand the features of rteval. rteval is a Python program
> used to measure real time performance. We wanted to test the effect of enabling
> some levels of idle-stat to see how it affects latency, and didn't want to
> reinvent the wheel. Since SWIG requires the .o files created by libcpupower at
> compilation it makes sense to include this in the cpupower directory so that
> others can make use of them.
> 
> The V2 of this patchset includes:
> * the full definition of libcpupower headers that is needed for the bindings
> * dummy implementation in C of a function listed in the header of libcpupower
> (requested by Shuah Khan)
> * test_raw_pylibcpupower.py demonstrates an example of using the bindings
> * adding myself and John Kacur to the cpupower section of the maintainers file
> (requested by Shuah Khan)
> * addressed review comments about doc, makefile, and maintainers file
> * small style and other fixes
> 
> The name raw_pylibcpupower is used because a wrapper `pylibcpupower` may be
> needed to make the bindings more 'pythonic' in the future. The bindings folder
> is used because Go or Perl bindings may be useful for other users in the
> future.
> 
> Note that while SWIG itself is GPL v3+ licensed; the resulting output, the
> bindings code, has the same license as the .o files used to generate the
> bindings (GPL v2 only). Please see
> https://swig.org/legal.html
> and
> https://lore.kernel.org/linux-pm/Zqv9BOjxLAgyNP5B@hatbackup/#t
> for more details on the license.
> 
> Sincerely,
> John Wyatt
> Software Engineer, Core Kernel
> Red Hat
> 
> John B. Wyatt IV (4):
>    Add SWIG bindings files for libcpupower
>    Implement dummy function for SWIG to accept the full library
>      definitions
>    Include test_raw_pylibcpupower.py
>    MAINTAINERS: Add Maintainers for SWIG Python bindings
> 
>   MAINTAINERS                                   |   3 +
>   .../power/cpupower/bindings/python/.gitignore |   8 +
>   tools/power/cpupower/bindings/python/Makefile |  31 +++
>   tools/power/cpupower/bindings/python/README   |  59 +++++
>   .../bindings/python/raw_pylibcpupower.i       | 247 ++++++++++++++++++
>   .../bindings/python/test_raw_pylibcpupower.py |  42 +++
>   tools/power/cpupower/lib/powercap.c           |   8 +
>   7 files changed, 398 insertions(+)
>   create mode 100644 tools/power/cpupower/bindings/python/.gitignore
>   create mode 100644 tools/power/cpupower/bindings/python/Makefile
>   create mode 100644 tools/power/cpupower/bindings/python/README
>   create mode 100644 tools/power/cpupower/bindings/python/raw_pylibcpupower.i
>   create mode 100755 tools/power/cpupower/bindings/python/test_raw_pylibcpupower.py
> 

Couple of things to address:

1. I noticed none of the patches have the subsystem prefix:
   pm:cpupower is the right prefix for patch subject for all
   the patches except the MAINTAINERS file

I will pull the fix  "Implement dummy function for SWIG to accept
the full library" Patch 2 in your series.

I want this subject changed to just fix as it is a problem irrespective
of SWIG - we have a missing function. Subject would be as follows:

""pm:cpupower: Add missing powercap_set_enabled() stub function"

Make this the first patch in the series. I will send this up for
Linux 6.11-rc7 or Linux 6.12-rc1

Depending on how the timelines for merge window work, expect the
series to land in Linux 6.13-rc1. I would prefer to delay it anyway
so we can get some soaking in next.

thanks,
-- Shuah