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authorMichel Lespinasse <walken@google.com>2012-10-08 19:31:25 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 03:22:39 -0400
commit6b2dbba8b6ac4df26f72eda1e5ea7bab9f950e08 (patch)
tree422ed8d7ac2fe45069f20cfba84a9a097bf444af /lib
parentfff3fd8a1210a165252cd7cd01206da7a90d3a06 (diff)
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 <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/interval_tree.c166
-rw-r--r--lib/prio_tree.c19
2 files changed, 12 insertions, 173 deletions
diff --git a/lib/interval_tree.c b/lib/interval_tree.c
index 6fd540b1e499..77a793e0644b 100644
--- a/lib/interval_tree.c
+++ b/lib/interval_tree.c
@@ -1,159 +1,13 @@
1#include <linux/init.h> 1#include <linux/init.h>
2#include <linux/interval_tree.h> 2#include <linux/interval_tree.h>
3 3
4/* Callbacks for augmented rbtree insert and remove */ 4#define ITSTRUCT struct interval_tree_node
5 5#define ITRB rb
6static inline unsigned long 6#define ITTYPE unsigned long
7compute_subtree_last(struct interval_tree_node *node) 7#define ITSUBTREE __subtree_last
8{ 8#define ITSTART(n) ((n)->start)
9 unsigned long max = node->last, subtree_last; 9#define ITLAST(n) ((n)->last)
10 if (node->rb.rb_left) { 10#define ITSTATIC
11 subtree_last = rb_entry(node->rb.rb_left, 11#define ITPREFIX interval_tree
12 struct interval_tree_node, rb)->__subtree_last; 12
13 if (max < subtree_last) 13#include <linux/interval_tree_tmpl.h>
14 max = subtree_last;
15 }
16 if (node->rb.rb_right) {
17 subtree_last = rb_entry(node->rb.rb_right,
18 struct interval_tree_node, rb)->__subtree_last;
19 if (max < subtree_last)
20 max = subtree_last;
21 }
22 return max;
23}
24
25RB_DECLARE_CALLBACKS(static, augment_callbacks, struct interval_tree_node, rb,
26 unsigned long, __subtree_last, compute_subtree_last)
27
28/* Insert / remove interval nodes from the tree */
29
30void interval_tree_insert(struct interval_tree_node *node,
31 struct rb_root *root)
32{
33 struct rb_node **link = &root->rb_node, *rb_parent = NULL;
34 unsigned long start = node->start, last = node->last;
35 struct interval_tree_node *parent;
36
37 while (*link) {
38 rb_parent = *link;
39 parent = rb_entry(rb_parent, struct interval_tree_node, rb);
40 if (parent->__subtree_last < last)
41 parent->__subtree_last = last;
42 if (start < parent->start)
43 link = &parent->rb.rb_left;
44 else
45 link = &parent->rb.rb_right;
46 }
47
48 node->__subtree_last = last;
49 rb_link_node(&node->rb, rb_parent, link);
50 rb_insert_augmented(&node->rb, root, &augment_callbacks);
51}
52
53void interval_tree_remove(struct interval_tree_node *node,
54 struct rb_root *root)
55{
56 rb_erase_augmented(&node->rb, root, &augment_callbacks);
57}
58
59/*
60 * Iterate over intervals intersecting [start;last]
61 *
62 * Note that a node's interval intersects [start;last] iff:
63 * Cond1: node->start <= last
64 * and
65 * Cond2: start <= node->last
66 */
67
68static struct interval_tree_node *
69subtree_search(struct interval_tree_node *node,
70 unsigned long start, unsigned long last)
71{
72 while (true) {
73 /*
74 * Loop invariant: start <= node->__subtree_last
75 * (Cond2 is satisfied by one of the subtree nodes)
76 */
77 if (node->rb.rb_left) {
78 struct interval_tree_node *left =
79 rb_entry(node->rb.rb_left,
80 struct interval_tree_node, rb);
81 if (start <= left->__subtree_last) {
82 /*
83 * Some nodes in left subtree satisfy Cond2.
84 * Iterate to find the leftmost such node N.
85 * If it also satisfies Cond1, that's the match
86 * we are looking for. Otherwise, there is no
87 * matching interval as nodes to the right of N
88 * can't satisfy Cond1 either.
89 */
90 node = left;
91 continue;
92 }
93 }
94 if (node->start <= last) { /* Cond1 */
95 if (start <= node->last) /* Cond2 */
96 return node; /* node is leftmost match */
97 if (node->rb.rb_right) {
98 node = rb_entry(node->rb.rb_right,
99 struct interval_tree_node, rb);
100 if (start <= node->__subtree_last)
101 continue;
102 }
103 }
104 return NULL; /* No match */
105 }
106}
107
108struct interval_tree_node *
109interval_tree_iter_first(struct rb_root *root,
110 unsigned long start, unsigned long last)
111{
112 struct interval_tree_node *node;
113
114 if (!root->rb_node)
115 return NULL;
116 node = rb_entry(root->rb_node, struct interval_tree_node, rb);
117 if (node->__subtree_last < start)
118 return NULL;
119 return subtree_search(node, start, last);
120}
121
122struct interval_tree_node *
123interval_tree_iter_next(struct interval_tree_node *node,
124 unsigned long start, unsigned long last)
125{
126 struct rb_node *rb = node->rb.rb_right, *prev;
127
128 while (true) {
129 /*
130 * Loop invariants:
131 * Cond1: node->start <= last
132 * rb == node->rb.rb_right
133 *
134 * First, search right subtree if suitable
135 */
136 if (rb) {
137 struct interval_tree_node *right =
138 rb_entry(rb, struct interval_tree_node, rb);
139 if (start <= right->__subtree_last)
140 return subtree_search(right, start, last);
141 }
142
143 /* Move up the tree until we come from a node's left child */
144 do {
145 rb = rb_parent(&node->rb);
146 if (!rb)
147 return NULL;
148 prev = &node->rb;
149 node = rb_entry(rb, struct interval_tree_node, rb);
150 rb = node->rb.rb_right;
151 } while (prev == rb);
152
153 /* Check if the node intersects [start;last] */
154 if (last < node->start) /* !Cond1 */
155 return NULL;
156 else if (start <= node->last) /* Cond2 */
157 return node;
158 }
159}
diff --git a/lib/prio_tree.c b/lib/prio_tree.c
index 4e0d2edff2b4..bba37148c15e 100644
--- a/lib/prio_tree.c
+++ b/lib/prio_tree.c
@@ -44,27 +44,12 @@
44 * The following macros are used for implementing prio_tree for i_mmap 44 * The following macros are used for implementing prio_tree for i_mmap
45 */ 45 */
46 46
47#define RADIX_INDEX(vma) ((vma)->vm_pgoff)
48#define VMA_SIZE(vma) (((vma)->vm_end - (vma)->vm_start) >> PAGE_SHIFT)
49/* avoid overflow */
50#define HEAP_INDEX(vma) ((vma)->vm_pgoff + (VMA_SIZE(vma) - 1))
51
52
53static void get_index(const struct prio_tree_root *root, 47static void get_index(const struct prio_tree_root *root,
54 const struct prio_tree_node *node, 48 const struct prio_tree_node *node,
55 unsigned long *radix, unsigned long *heap) 49 unsigned long *radix, unsigned long *heap)
56{ 50{
57 if (root->raw) { 51 *radix = node->start;
58 struct vm_area_struct *vma = prio_tree_entry( 52 *heap = node->last;
59 node, struct vm_area_struct, shared.prio_tree_node);
60
61 *radix = RADIX_INDEX(vma);
62 *heap = HEAP_INDEX(vma);
63 }
64 else {
65 *radix = node->start;
66 *heap = node->last;
67 }
68} 53}
69 54
70static unsigned long index_bits_to_maxindex[BITS_PER_LONG]; 55static unsigned long index_bits_to_maxindex[BITS_PER_LONG];
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