Question about quantifying Linux kernel functional growth across releases

[陈鑫]

Hello,

I am analyzing how the Linux kernel evolves across releases, for
example 4.19, 5.4, 5.10, 5.15, 6.1, and 6.6.

I am looking for a technically meaningful and reproducible way to
quantify changes in the kernel's functional scope over time.

I understand that there is no well-defined concept of a "number of
features" in the Linux kernel. One metric I am considering is the
number of unique Kconfig symbols in each release, since Kconfig
represents a broad range of configurable kernel capabilities,
including subsystems, device drivers, architecture support,
filesystems, networking, security features, and so on.

For example, I am considering collecting statistics such as:

* total number of unique Kconfig symbols in each release;
* number of symbols added and removed between releases;
* changes grouped by major areas such as drivers, networking,
filesystems, security, and architecture.

I would appreciate the community's views on the following questions:

1. Is the number of Kconfig symbols a reasonable proxy for comparing
the functional scope of different kernel releases?

2. What are the main limitations or pitfalls of using Kconfig symbols
for this purpose?

3. Are there other quantitative metrics that kernel developers
consider more meaningful for describing the growth or evolution of
kernel capabilities?

4. Are there existing tools, kernel.org statistics, or
community-maintained datasets that track this kind of evolution across
releases?

My intention is not to claim an exact "feature count" for Linux. I am
trying to identify a metric, or preferably a combination of metrics,
that is technically defensible, reproducible, and suitable for
comparing kernel evolution over time.

Any suggestions, references, or pointers to previous discussions would
be greatly appreciated.

Thanks,
Xin Chen