Where 2.6.25 came from [LWN.net]

Where 2.6.25 came from

Posted Apr 3, 2008 12:34 UTC (Thu) by lacostej (guest, #2760)
Parent article: Where 2.6.25 came from

What would be interesting is to compare information found in the first graph, e.g.
* size of the 'stair-step'
* comparison of the stair size with the release period length
* stabilization (e.g. inclination angle of the slope after the stair)
* average amount of reviews per change
* ...
with external information (perceived or computed stability, number of security issues
introduced in a release, holidays)

From my readings of the graph
the last 2 kernels have very steep merge. 2.6.19 started merging late
2.6.22 has had more late merges than its successors
2.6.20 seems to have stabilized early
2.6.16 seems to have had a bad stabilization

to post comments

Where 2.6.25 came from

Posted Apr 4, 2008 20:41 UTC (Fri) by roelofs (guest, #2599) [Link] (1 responses)

2.6.16 seems to have had a bad stabilization

2.6.16 is mostly off the graph. Are you off by one?

Greg

Where 2.6.25 came from

Posted Apr 5, 2008 5:27 UTC (Sat) by lacostej (guest, #2760) [Link]

"2.6.16 is mostly off the graph. Are you off by one?"

yep. I think I got the others right.

Where 2.6.25 came from

Posted Apr 6, 2008 10:28 UTC (Sun) by bunk (subscriber, #44933) [Link] (1 responses)

You said:
From my readings of the graph
the last 2 kernels have very steep merge. 2.6.19 started merging late
2.6.22 has had more late merges than its successors
2.6.20 seems to have stabilized early

Don't believe any statistics you haven't faked yourself.

There is no strong relation between the number of changes and the number of lines changed.

And none of them has any strong relation to when a kernel stabilizes.

An increase in the "count of lines changed over time" graph can e.g. be one or more of the
following:
* many bugfixes
* defconfig updates
* addition or removal of drivers

It's a nice graph, but when you ignore the fact that it contains zero information *why* lines
changed all conclusions you draw are invalid.

Where 2.6.25 came from

Posted Apr 6, 2008 10:59 UTC (Sun) by bunk (subscriber, #44933) [Link]

I just notice I forgot to add a smiley after the "Don't believe any statistics you haven't
faked yourself."

I don't claim this graph was faked (I haven't checked, but it's most likely correct).

But it's important to realize that the scale of the graph means that for example the step you
see one month before the release of 2.6.23 can easily equal 100.000 lines of code (the
re-addition of the sk98lin driver alone were over 40.000 lines of code).

Stabilization, also known as bugfixing, tends to consist of small patches (usually < 100 lines
changed, often even < 10 lines changed).

And these patches are simply too small for having any visible effect on a "count of lines
changed" graph for the Linux kernel.

Check e.g. http://lwn.net/Articles/274992/ for an explanation by Linus himself regarding what
causes most of the line changes later in the release cycle.