Re: 2.6.25-rc3-git3: Reported regressions from 2.6.24

From: Ingo Molnar
Date: Wed Mar 05 2008 - 01:57:48 EST



* Zhang, Yanmin <yanmin_zhang@xxxxxxxxxxxxxxx> wrote:

> > Have you had a chance to git-bisect the culprit after the revert?
>
> How to bisect it if the reverted patch is submitted after the culprit
> patch?

i do this by using quilt ontop of git-bisect.

I do something like this:

mkdir patches
echo revert.patch > patches/series
git-log -1 -p 62fb185130e4d420f > patches/revert.patch

git-bisect start
git-bisect bad v2.6.24-rc3
git-bisect good v2.6.24

quilt push # the revert is applied
[ test the kernel ]
quilt pop # revert is unapplied

git-bisect bad # if it's still bad

quilt push # apply the revert again
[ test the next kernel ]
quilt pop # undo the revert

git-bisect good # if it's good

etc. NOTE: if the "quilt push" fails, it's likely because you are in a
point in the tree that does not have the reverted commits applied yet.
In that case there's no need to push/pop, just test the bisection point.

Note, since there are _two_ guilty commits here:

commit 58e2d4ca581167c2a079f4ee02be2f0bc52e8729
Author: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
Date: Fri Jan 25 21:08:00 2008 +0100
sched: group scheduling, change how cpu load is calculated

commit 6b2d7700266b9402e12824e11e0099ae6a4a6a79
Author: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
Date: Fri Jan 25 21:08:00 2008 +0100
sched: group scheduler, fix fairness of cpu bandwidth allocation for task

make sure the bisection point is never "between" these two commits.

You can check whether a bisection point has the two guilty commits
applied, via:

git-log | grep -E '58e2d4ca581167c2a0|6b2d7700266b9402e12'

if this comes up empty, the guilty commits are not applied.

Ingo
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