Re: [regression] commit 6a4f3b52 causes invalid memtype

From: Ali Gholami Rudi
Date: Mon Jul 05 2010 - 07:58:16 EST


Ingo Molnar <mingo@xxxxxxx> wrote:
> > > >> commit 2463eb8b3093995e09a0d41b3d78ee0cf5fb4249
> > > >> Author: Peter Zijlstra<peterz@xxxxxxxxxxxxx>
> > > >> Date: Sat May 29 15:31:43 2010 +0200
> > > >>
> > > >> rbtree: Undo augmented trees performance damage
> > > >
> > > > Where can I get it? I couldn't find it either in
> > > > Linus' or x86 repo tip.
> > > http://git.kernel.org/tip/2463eb8b3093995e09a0d41b3d78ee0cf5fb4249
> >
> > It does fix it.
>
> Hm, interesting. That's a pure performance fix - so why does it fix a
> regression?
>
> Does Peter's augmented rbtrees improvements fix a bug too, as a side-effect?
> If yes then we need to accelerate that commit - right now it's aimed for
> v2.6.36.

Since the bug appears after commit 6a4f3b52, it seems to be
related to the value of memtype->subtree_max_end. Peter's
patch seems to change the way memtype->subtree_max_end is
updated, which seems to fix the problem too.

Thanks,
Ali

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