On Tue, Jun 1, 2010 at 10:19 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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@xxxxxxxxx>
> ---
> 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 */
>
>
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