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mm: replace vma prio_tree with an interval tree
Implement an interval tree as a replacement for the VMA prio_tree. The algorithms are similar to lib/interval_tree.c; however that code can't be directly reused as the interval endpoints are not explicitly stored in the VMA. So instead, the common algorithm is moved into a template and the details (node type, how to get interval endpoints from the node, etc) are filled in using the C preprocessor. Once the interval tree functions are available, using them as a replacement to the VMA prio tree is a relatively simple, mechanical job. Signed-off-by: Michel Lespinasse <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Hillf Danton <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: David Woodhouse <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,215 @@ | ||
| /* | ||
| Interval Trees | ||
| (C) 2012 Michel Lespinasse <[email protected]> | ||
| This program is free software; you can redistribute it and/or modify | ||
| it under the terms of the GNU General Public License as published by | ||
| the Free Software Foundation; either version 2 of the License, or | ||
| (at your option) any later version. | ||
| This program is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| GNU General Public License for more details. | ||
| You should have received a copy of the GNU General Public License | ||
| along with this program; if not, write to the Free Software | ||
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
| include/linux/interval_tree_tmpl.h | ||
| */ | ||
|
|
||
| /* | ||
| * Template for implementing interval trees | ||
| * | ||
| * ITSTRUCT: struct type of the interval tree nodes | ||
| * ITRB: name of struct rb_node field within ITSTRUCT | ||
| * ITTYPE: type of the interval endpoints | ||
| * ITSUBTREE: name of ITTYPE field within ITSTRUCT holding last-in-subtree | ||
| * ITSTART(n): start endpoint of ITSTRUCT node n | ||
| * ITLAST(n): last endpoing of ITSTRUCT node n | ||
| * ITSTATIC: 'static' or empty | ||
| * ITPREFIX: prefix to use for the inline tree definitions | ||
| */ | ||
|
|
||
| /* IT(name) -> ITPREFIX_name */ | ||
| #define _ITNAME(prefix, name) prefix ## _ ## name | ||
| #define ITNAME(prefix, name) _ITNAME(prefix, name) | ||
| #define IT(name) ITNAME(ITPREFIX, name) | ||
|
|
||
| /* Callbacks for augmented rbtree insert and remove */ | ||
|
|
||
| static inline ITTYPE IT(compute_subtree_last)(ITSTRUCT *node) | ||
| { | ||
| ITTYPE max = ITLAST(node), subtree_last; | ||
| if (node->ITRB.rb_left) { | ||
| subtree_last = rb_entry(node->ITRB.rb_left, | ||
| ITSTRUCT, ITRB)->ITSUBTREE; | ||
| if (max < subtree_last) | ||
| max = subtree_last; | ||
| } | ||
| if (node->ITRB.rb_right) { | ||
| subtree_last = rb_entry(node->ITRB.rb_right, | ||
| ITSTRUCT, ITRB)->ITSUBTREE; | ||
| if (max < subtree_last) | ||
| max = subtree_last; | ||
| } | ||
| return max; | ||
| } | ||
|
|
||
| static void IT(augment_propagate)(struct rb_node *rb, struct rb_node *stop) | ||
| { | ||
| while (rb != stop) { | ||
| ITSTRUCT *node = rb_entry(rb, ITSTRUCT, ITRB); | ||
| ITTYPE subtree_last = IT(compute_subtree_last)(node); | ||
| if (node->ITSUBTREE == subtree_last) | ||
| break; | ||
| node->ITSUBTREE = subtree_last; | ||
| rb = rb_parent(&node->ITRB); | ||
| } | ||
| } | ||
|
|
||
| static void IT(augment_copy)(struct rb_node *rb_old, struct rb_node *rb_new) | ||
| { | ||
| ITSTRUCT *old = rb_entry(rb_old, ITSTRUCT, ITRB); | ||
| ITSTRUCT *new = rb_entry(rb_new, ITSTRUCT, ITRB); | ||
|
|
||
| new->ITSUBTREE = old->ITSUBTREE; | ||
| } | ||
|
|
||
| static void IT(augment_rotate)(struct rb_node *rb_old, struct rb_node *rb_new) | ||
| { | ||
| ITSTRUCT *old = rb_entry(rb_old, ITSTRUCT, ITRB); | ||
| ITSTRUCT *new = rb_entry(rb_new, ITSTRUCT, ITRB); | ||
|
|
||
| new->ITSUBTREE = old->ITSUBTREE; | ||
| old->ITSUBTREE = IT(compute_subtree_last)(old); | ||
| } | ||
|
|
||
| static const struct rb_augment_callbacks IT(augment_callbacks) = { | ||
| IT(augment_propagate), IT(augment_copy), IT(augment_rotate) | ||
| }; | ||
|
|
||
| /* Insert / remove interval nodes from the tree */ | ||
|
|
||
| ITSTATIC void IT(insert)(ITSTRUCT *node, struct rb_root *root) | ||
| { | ||
| struct rb_node **link = &root->rb_node, *rb_parent = NULL; | ||
| ITTYPE start = ITSTART(node), last = ITLAST(node); | ||
| ITSTRUCT *parent; | ||
|
|
||
| while (*link) { | ||
| rb_parent = *link; | ||
| parent = rb_entry(rb_parent, ITSTRUCT, ITRB); | ||
| if (parent->ITSUBTREE < last) | ||
| parent->ITSUBTREE = last; | ||
| if (start < ITSTART(parent)) | ||
| link = &parent->ITRB.rb_left; | ||
| else | ||
| link = &parent->ITRB.rb_right; | ||
| } | ||
|
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||
| node->ITSUBTREE = last; | ||
| rb_link_node(&node->ITRB, rb_parent, link); | ||
| rb_insert_augmented(&node->ITRB, root, &IT(augment_callbacks)); | ||
| } | ||
|
|
||
| ITSTATIC void IT(remove)(ITSTRUCT *node, struct rb_root *root) | ||
| { | ||
| rb_erase_augmented(&node->ITRB, root, &IT(augment_callbacks)); | ||
| } | ||
|
|
||
| /* | ||
| * Iterate over intervals intersecting [start;last] | ||
| * | ||
| * Note that a node's interval intersects [start;last] iff: | ||
| * Cond1: ITSTART(node) <= last | ||
| * and | ||
| * Cond2: start <= ITLAST(node) | ||
| */ | ||
|
|
||
| static ITSTRUCT *IT(subtree_search)(ITSTRUCT *node, ITTYPE start, ITTYPE last) | ||
| { | ||
| while (true) { | ||
| /* | ||
| * Loop invariant: start <= node->ITSUBTREE | ||
| * (Cond2 is satisfied by one of the subtree nodes) | ||
| */ | ||
| if (node->ITRB.rb_left) { | ||
| ITSTRUCT *left = rb_entry(node->ITRB.rb_left, | ||
| ITSTRUCT, ITRB); | ||
| if (start <= left->ITSUBTREE) { | ||
| /* | ||
| * Some nodes in left subtree satisfy Cond2. | ||
| * Iterate to find the leftmost such node N. | ||
| * If it also satisfies Cond1, that's the match | ||
| * we are looking for. Otherwise, there is no | ||
| * matching interval as nodes to the right of N | ||
| * can't satisfy Cond1 either. | ||
| */ | ||
| node = left; | ||
| continue; | ||
| } | ||
| } | ||
| if (ITSTART(node) <= last) { /* Cond1 */ | ||
| if (start <= ITLAST(node)) /* Cond2 */ | ||
| return node; /* node is leftmost match */ | ||
| if (node->ITRB.rb_right) { | ||
| node = rb_entry(node->ITRB.rb_right, | ||
| ITSTRUCT, ITRB); | ||
| if (start <= node->ITSUBTREE) | ||
| continue; | ||
| } | ||
| } | ||
| return NULL; /* No match */ | ||
| } | ||
| } | ||
|
|
||
| ITSTATIC ITSTRUCT *IT(iter_first)(struct rb_root *root, | ||
| ITTYPE start, ITTYPE last) | ||
| { | ||
| ITSTRUCT *node; | ||
|
|
||
| if (!root->rb_node) | ||
| return NULL; | ||
| node = rb_entry(root->rb_node, ITSTRUCT, ITRB); | ||
| if (node->ITSUBTREE < start) | ||
| return NULL; | ||
| return IT(subtree_search)(node, start, last); | ||
| } | ||
|
|
||
| ITSTATIC ITSTRUCT *IT(iter_next)(ITSTRUCT *node, ITTYPE start, ITTYPE last) | ||
| { | ||
| struct rb_node *rb = node->ITRB.rb_right, *prev; | ||
|
|
||
| while (true) { | ||
| /* | ||
| * Loop invariants: | ||
| * Cond1: ITSTART(node) <= last | ||
| * rb == node->ITRB.rb_right | ||
| * | ||
| * First, search right subtree if suitable | ||
| */ | ||
| if (rb) { | ||
| ITSTRUCT *right = rb_entry(rb, ITSTRUCT, ITRB); | ||
| if (start <= right->ITSUBTREE) | ||
| return IT(subtree_search)(right, start, last); | ||
| } | ||
|
|
||
| /* Move up the tree until we come from a node's left child */ | ||
| do { | ||
| rb = rb_parent(&node->ITRB); | ||
| if (!rb) | ||
| return NULL; | ||
| prev = &node->ITRB; | ||
| node = rb_entry(rb, ITSTRUCT, ITRB); | ||
| rb = node->ITRB.rb_right; | ||
| } while (prev == rb); | ||
|
|
||
| /* Check if the node intersects [start;last] */ | ||
| if (last < ITSTART(node)) /* !Cond1 */ | ||
| return NULL; | ||
| else if (start <= ITLAST(node)) /* Cond2 */ | ||
| return node; | ||
| } | ||
| } |
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