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

[Ingo Molnar <mingo@elte.hu>]

* Zhang, Yanmin <yanmin_zhang@linux.intel.com> 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@linux.vnet.ibm.com>
      Date:   Fri Jan 25 21:08:00 2008 +0100
      sched: group scheduling, change how cpu load is calculated

      commit 6b2d7700266b9402e12824e11e0099ae6a4a6a79
      Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
      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