How can I get statistics about how much (in percents) the Linux kernel source code changes in one year?
Linux – How much does the Linux kernel change in one year
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The Linux kernel itself is all free software, distributed under the GNU General Public License.
Third parties may distribute closed-source drivers in the form of loadable kernel modules. There's some debate as to whether the GPL allows them; Linus Torvalds has decreed that proprietary modules are allowed.
Many device in today's computer contain a processor and a small amount of volatile memory, and need some code to be loaded into that volatile memory in order to be fully operational. This code is called firmware. Note that the difference between a driver and a firmware is that the firmware is running on a different processor. Firmware makers often only release a binary blob with no code source. Many Linux distributions package non-free firmware separately (or in extreme cases not at all), e.g. Debian.
Kernel is a bit of a misnomer. The Linux kernel is comprised of several proceses/threads + the modules (lsmod) so to get a complete picture you'd need to look at the whole ball and not just a single component.
Incidentally mine shows slabtop:
Active / Total Size (% used) : 173428.30K / 204497.61K (84.8%)
The man page for slabtop also had this to say:
The slabtop statistic header is tracking how many bytes of slabs are being used and it not a measure of physical memory. The 'Slab' field in the /proc/meminfo file is tracking information about used slab physical memory.
Dropping caches
Dropping my caches as @derobert suggested in the comments under your question does the following for me:
$ sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'
$
Active / Total Size (% used) : 61858.78K / 90524.77K (68.3%)
Sending a 3 does the following: free pagecache, dentries and inodes. I discuss this more in this U&L Q&A titled: Are there any ways or tools to dump the memory cache and buffer?". So 110MB of my space was being used by just maintaining the info regarding pagecache, dentries and inodes.
Additional Information
- If you're interested I found this blog post that discusses
slabtopin a bit more details. It's titled: Linux command of the day: slabtop. - The Slab Cache is discussed in more detail here on Wikipedia, titled: Slab allocation.
So how much RAM is my Kernel using?
This picture is a bit foggier to me, but here are the things that I "think" we know.
Slab
We can get a snapshot of the Slab usage using this technique. Essentially we can pull this information out of /proc/meminfo.
$ grep Slab /proc/meminfo
Slab: 100728 kB
Modules
Also we can get a size value for Kernel modules (unclear whether it's their size from on disk or when in RAM) by pulling these values from /proc/modules:
$ awk '{print $1 " " $2 }' /proc/modules | head -5
cpufreq_powersave 1154
tcp_lp 2111
aesni_intel 12131
cryptd 7111
aes_x86_64 7758
Slabinfo
Much of the details about the SLAB are accessible in this proc structure, /proc/slabinfo:
$ less /proc/slabinfo | head -5
slabinfo - version: 2.1
# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata <active_slabs> <num_slabs> <sharedavail>
nf_conntrack_ffff8801f2b30000 0 0 320 25 2 : tunables 0 0 0 : slabdata 0 0 0
fuse_request 100 125 632 25 4 : tunables 0 0 0 : slabdata 5 5 0
fuse_inode 21 21 768 21 4 : tunables 0 0 0 : slabdata 1 1 0
Dmesg
When your system boots there is a line that reports memory usage of the Linux kernel just after it's loaded.
$ dmesg |grep Memory:
[ 0.000000] Memory: 7970012k/9371648k available (4557k kernel code, 1192276k absent, 209360k reserved, 7251k data, 948k init)
Best Answer
What you are looking for can be found on the Ohloh website, which by the way indexes the Linux GIT repository. There you will see a graph showing you how much the kernel has changed over 1 yr, 3 yrs, 5 yrs, 10 yrs or All. By default it will show you the statistics for the source code but you can also get statistics about Languages, Committers, Commits. You can then manually calculate the change %. The change in source code between 2010 and 2011 is up 11.4%.