Date based [LWN.net]

Date based

Posted May 24, 2011 7:43 UTC (Tue) by corsac (subscriber, #49696)
In reply to: Date based by dlang
Parent article: 2.8.0?

> either way you do the date thing, you can then see how old the base kernel is, and figure out how recently it was updated (which also lets you notice when an old kernel series is no longer being updated)

My point is that we (usually) don't care how old the base kernel is for stable series.

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Date based

Posted May 24, 2011 8:30 UTC (Tue) by dlang (guest, #313) [Link] (1 responses)

in my opinion you should care about how old the base of a kernel is.

there are a _lot_ of things that don't get backported, some is hardware support, some is performance improvements, some are cleanups of code that may or may not fix bugs, some are bugfixes that people don't think are important enough, some are bugfixes that are considered too intrusive/dangerous to backport.

the number of people working on doing backports is rather small compared to the number of people working on the latest versions

look at the number of patches in a -stable release, even the big ones are seldom more than 100-200 changesets, out of the 10,000 or so changesets in each new release. even if there are a LOT of -stable releases for a particular kernel, the number of changes that get backported are considerably less than 10% of the changes that go into the next release, and as a kernel gets older, fewer changes are backported. by the time you get to a kernel that's 10 releases back, I would guess that far fewer than 1% of the changes have been backported

actually, we can look at numbers for this (fun with git)

2.6.27 - 2.6.37 had 113521 changesets
2.6.27 - 2.6.27.57 had 2891 changesets

2.6.32 - 2.6.39 had 76108 changesets
2.6.32 - 2.6.32.27 had 2892 changesets

2.6.38 - 2.6.29 had 11031 changesets
2.6.38 - 2.6.38.7 had 3101 changesets

so I was a little off in my 1% guess, and I don't have the most recent versions of all the longterm kernels (I pulled from kernel.org and from the stable tree)

but do you really want to bet that the rest of the changes that did't get backported are really all for things you don't need?

Date based

Posted May 24, 2011 8:36 UTC (Tue) by corsac (subscriber, #49696) [Link]

> look at the number of patches in a -stable release, even the big ones are seldom more than 100-200 changesets, out of the 10,000 or so changesets in each new release.

This is more an advantage than a drawback.

> the number of people working on doing backports is rather small compared to the number of people working on the latest versions

Sure, but the changes are different too. And that's also why a lot of distributions use 2.6.32 for their stable, long time support release. So the stable maintenance work is shared.

> even if there are a LOT of -stable releases for a particular kernel, the number of changes that get backported are considerably less than 10% of the changes that go into the next release, and as a kernel gets older, fewer changes are backported. by the time you get to a kernel that's 10 releases back, I would guess that far fewer than 1% of the changes have been backported

That's the whole point of having stable releases.

> but do you really want to bet that the rest of the changes that did't get backported are really all for things you don't need?

Yes