Messages in this thread | | | Subject | Re: [PATCH -mm v2 01/11] mm: track free size between VMAs in VMA rbtree | From | Peter Zijlstra <> | Date | Tue, 26 Jun 2012 15:45:49 +0200 |
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On Tue, 2012-06-26 at 09:05 -0400, Rik van Riel wrote: > On 06/26/2012 04:31 AM, Peter Zijlstra wrote: > > > If you look at your patch 1, __vma_unlink has an adjust_free_gap() right > > next to the rb_augment_erase(), vma_adjust() has 3 adjust_free_gap() > > calls right next to each other. > > > > All these will do an entire path walk back to the root. I would think we > > could save quite a bit of updating by not having them all walk back to > > the root. No point in re-computing the top levels if you know the next > > update will change them again anyway. > > The problem is, unless we look at the augmented data at > rotate time, we do not know when it is safe to stop > iterating up the tree.
argh,.. you're using adjust_vma_gap() for insertions instead of rb_augment_insert().
I was going on the premise that you're doing updates for augmented data without modifying the tree structure and that doing insert/delete will keep the stuff up-to-date.
So now I'm not sure why you do if (insert) adjust_free_gap(insert), since __insert_vm_struct(mm, insert) -> __vma_link() -> __vma_link_rb() already does an augment update.
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