lkml.org 
[lkml]   [2010]   [Jun]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH] rbtree: undo augmented damage -v2
    From
    On Tue, Jun 1, 2010 at 10:19 AM, Peter Zijlstra <peterz@infradead.org> wrote:
    > On Tue, 2010-06-01 at 10:00 -0700, Venkatesh Pallipadi wrote:
    >> I am not seeing how this can cover all the callbacks we will need to
    >> maintain the augmented tree property. May be I am missing something.
    >
    > Yes, indeed, how about the below delta, which my eevdf code did do but I
    > overlooked on the conversion to the PAT code.
    >
    > That removes the break as you said, but also adds code to update the
    > child nodes when walking up the path.
    >
    > So in your rotation case:
    >
    >    G             P
    >   / \    -->    / \
    >  P   U         N   G
    >  /        <--        \
    > N                     U
    >
    > Say we take the right rotation, then the traversal up from N to P will
    > find that since N was the left child of P and it has a right child (G)
    > it will also update G.

    Yes. This will cover all the cases on insert. But on erase, there is
    still a case where a rotate of sibling node is done during the
    re-coloration process. There we have a child change on sibling's
    child. I am not able to think of any easy way to handle that case.

    Thanks,
    Venki

    >
    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > ---
    >  arch/x86/mm/pat_rbtree.c |   23 ++++++++++++-----------
    >  1 files changed, 12 insertions(+), 11 deletions(-)
    >
    > diff --git a/arch/x86/mm/pat_rbtree.c b/arch/x86/mm/pat_rbtree.c
    > index f537087..ca19aae 100644
    > --- a/arch/x86/mm/pat_rbtree.c
    > +++ b/arch/x86/mm/pat_rbtree.c
    > @@ -81,20 +81,21 @@ static void update_node_max_end(struct rb_node *node)
    >  /* Update 'subtree_max_end' for a node and all its ancestors */
    >  static void update_path_max_end(struct rb_node *node)
    >  {
    > -       u64 old_max_end, new_max_end;
    > +       struct rb_node *parent;
    >
    > -       while (node) {
    > -               struct memtype *data = container_of(node, struct memtype, rb);
    > -
    > -               old_max_end = data->subtree_max_end;
    > -               update_node_max_end(node);
    > -               new_max_end = data->subtree_max_end;
    > +up:
    > +       update_node_max_end(node);
    > +       parent = rb_parent(node);
    > +       if (!parent)
    > +               return;
    >
    > -               if (new_max_end == old_max_end)
    > -                       break;
    > +       if (node == parent->rb_left && parent->rb_right)
    > +               update_node_max_end(parent->rb_right);
    > +       else if (parent->rb_left)
    > +               update_node_max_end(parent->rb_left);
    >
    > -               node = rb_parent(node);
    > -       }
    > +       node = parent;
    > +       goto up;
    >  }
    >
    >  /* Find the first (lowest start addr) overlapping range from rb tree */
    >
    >
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2010-06-01 19:37    [W:0.026 / U:1.356 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site