* Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> [231218 15:20]:
> * Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx> [231215 02:46]:
> > The last range stored in maple tree is typically quite large. By
> > checking if it exceeds the sum of the remaining ranges in that node, it
> > is possible to avoid checking all other gaps.
> >
> > Running the maple tree test suite in user mode almost always results in
> > a near 100% hit rate for this optimization.
>
> This should only be triggered for right-most nodes and root though,
> correct (mas->max == ULONG_MAX from just before this)?
>
> I wonder if it's worth special case checking the first gap if the node
> min is 0 as well. Might be worth looking at, but this patch is
> certainly worth doing.
Actually, not just when the min is 0, we have a special case close to
here for slot 0 so we could just check the same sort of thing there.
>
> >
> > Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
>
> Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
>
> > ---
> > lib/maple_tree.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> > index c9a970ea20dd..6f241bb38799 100644
> > --- a/lib/maple_tree.c
> > +++ b/lib/maple_tree.c
> > @@ -1518,6 +1518,9 @@ static unsigned long mas_leaf_max_gap(struct ma_state *mas)
> > gap = ULONG_MAX - pivots[max_piv];
> > if (gap > max_gap)
> > max_gap = gap;
> > +
> > + if (max_gap > pivots[max_piv] - mas->min)
> > + return max_gap;
> > }
> >
> > for (; i <= max_piv; i++) {
> > --
> > 2.20.1
> >
