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Message-ID: <4F716CB5.5010303@redhat.com>
Date: Tue, 27 Mar 2012 09:31:01 +0200
From: Avi Kivity <avi@...hat.com>
To: Ingo Molnar <mingo@...nel.org>
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
KVM list <kvm@...r.kernel.org>,
Marcelo Tosatti <mtosatti@...hat.com>,
Paul Mackerras <paulus@....ibm.com>,
Alexander Graf <agraf@...e.de>
Subject: Re: [GIT PULL] KVM updates for the 3.4 merge window
On 03/26/2012 06:21 PM, Ingo Molnar wrote:
> * Avi Kivity <avi@...hat.com> wrote:
>
> > Say a fix comes in which needs to be mainlined during -rc. So
> > I put it in some other branch, to be sent off to Linus in a
> > few days after maturing a little. Meanwhile developers see an
> > incomplete tree, since that patch is not in it.
> >
> > Once Linus pulls, I can merge it back (or even before, if I'm
> > reasonably certain it's not going to change), but it leaves a
> > history of unneeded merges. Or we can do throwaway merges
> > like tip.git.
>
> We don't do throwaway merges in the -tip development branches
> themselves, i.e. in tip:sched/core, tip:perf/core,
> tip:timers/core, etc.
>
> When a fix goes into tip:sched/urgent then until Linus merges it
> it's not in tip:sched/core. 99% of the fixes don't *have to* go
> into sched/core straight away.
>
> In the odd case where there's some dependency, we can manually
> merge it into tip:sched/core ahead of Linus pulling into an -rc.
> Those rare merges are not a problem, and I explain the reason in
> the merge commit itself.
>
> If you look at:
>
> gll v3.2..v3.3 | grep -E '/urgent.*/core'
>
> you'll see that I only had to do it once in the previous cycle:
>
> d6c1c49de577 Merge branch 'perf/urgent' into perf/core
>
> and the changelog explains the background:
>
> Merge reason: Add these cherry-picked commits so that future changes
> on perf/core don't conflict.
>
> it was a rare, oddball situation where we cherry-picked
> perf/core changes into perf/urgent. Extra merges are perfectly
> fine in that case.
>
> The 'throwaway' tip:master branch you are probably referring to
> is basically just a testing branch, a convenient merged tree of
> the one dozen maintainer trees that are hosted in -tip. Since we
> don't want to force Linus's hand of him being able to reject
> individual trees we don't merge them properly - hence the
> integrated tree is a throwaway tree in theory.
>
> In practice I tend to throw it away only once per cycle, around
> -rc1, once all pending trees went to Linus. tip:master is not
> used for any Git based contribution work - it's for testing,
> it's for people who want to work with patches - the commits
> themselves always go into persistent non-rebasing, append-only
> Git trees.
>
> If we mess up bisectability we do a delta fix. When choosing
> between somewhat better bisectability and a proper history that
> others can rely on then proper history wins hands down.
>
Okay, we'll adopt a similar workflow for the future.
--
error compiling committee.c: too many arguments to function
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