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authorMichel Lespinasse <walken@google.com>2012-10-08 16:31:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:39 +0900
commit6b2dbba8b6ac4df26f72eda1e5ea7bab9f950e08 (patch)
tree422ed8d7ac2fe45069f20cfba84a9a097bf444af /mm/prio_tree.c
parentfff3fd8a1210a165252cd7cd01206da7a90d3a06 (diff)
downloadlinux-sh-6b2dbba8b6ac4df26f72eda1e5ea7bab9f950e08.tar.gz
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 'mm/prio_tree.c')
-rw-r--r--mm/prio_tree.c208
1 files changed, 0 insertions, 208 deletions
diff --git a/mm/prio_tree.c b/mm/prio_tree.c
deleted file mode 100644
index 799dcfd7cd8c..000000000000
--- a/mm/prio_tree.c
+++ /dev/null
@@ -1,208 +0,0 @@
-/*
- * mm/prio_tree.c - priority search tree for mapping->i_mmap
- *
- * Copyright (C) 2004, Rajesh Venkatasubramanian <vrajesh@umich.edu>
- *
- * This file is released under the GPL v2.
- *
- * Based on the radix priority search tree proposed by Edward M. McCreight
- * SIAM Journal of Computing, vol. 14, no.2, pages 257-276, May 1985
- *
- * 02Feb2004 Initial version
- */
-
-#include <linux/mm.h>
-#include <linux/prio_tree.h>
-#include <linux/prefetch.h>
-
-/*
- * See lib/prio_tree.c for details on the general radix priority search tree
- * code.
- */
-
-/*
- * The following #defines are mirrored from lib/prio_tree.c. They're only used
- * for debugging, and should be removed (along with the debugging code using
- * them) when switching also VMAs to the regular prio_tree code.
- */
-
-#define RADIX_INDEX(vma) ((vma)->vm_pgoff)
-#define VMA_SIZE(vma) (((vma)->vm_end - (vma)->vm_start) >> PAGE_SHIFT)
-/* avoid overflow */
-#define HEAP_INDEX(vma) ((vma)->vm_pgoff + (VMA_SIZE(vma) - 1))
-
-/*
- * Radix priority search tree for address_space->i_mmap
- *
- * For each vma that map a unique set of file pages i.e., unique [radix_index,
- * heap_index] value, we have a corresponding priority search tree node. If
- * multiple vmas have identical [radix_index, heap_index] value, then one of
- * them is used as a tree node and others are stored in a vm_set list. The tree
- * node points to the first vma (head) of the list using vm_set.head.
- *
- * prio_tree_root
- * |
- * A vm_set.head
- * / \ /
- * L R -> H-I-J-K-M-N-O-P-Q-S
- * ^ ^ <-- vm_set.list -->
- * tree nodes
- *
- * We need some way to identify whether a vma is a tree node, head of a vm_set
- * list, or just a member of a vm_set list. We cannot use vm_flags to store
- * such information. The reason is, in the above figure, it is possible that
- * vm_flags' of R and H are covered by the different mmap_sems. When R is
- * removed under R->mmap_sem, H replaces R as a tree node. Since we do not hold
- * H->mmap_sem, we cannot use H->vm_flags for marking that H is a tree node now.
- * That's why some trick involving shared.vm_set.parent is used for identifying
- * tree nodes and list head nodes.
- *
- * vma radix priority search tree node rules:
- *
- * vma->shared.vm_set.parent != NULL ==> a tree node
- * vma->shared.vm_set.head != NULL ==> list of others mapping same range
- * vma->shared.vm_set.head == NULL ==> no others map the same range
- *
- * vma->shared.vm_set.parent == NULL
- * vma->shared.vm_set.head != NULL ==> list head of vmas mapping same range
- * vma->shared.vm_set.head == NULL ==> a list node
- */
-
-/*
- * Add a new vma known to map the same set of pages as the old vma:
- * useful for fork's dup_mmap as well as vma_prio_tree_insert below.
- * Note that it just happens to work correctly on i_mmap_nonlinear too.
- */
-void vma_prio_tree_add(struct vm_area_struct *vma, struct vm_area_struct *old)
-{
- /* Leave these BUG_ONs till prio_tree patch stabilizes */
- BUG_ON(RADIX_INDEX(vma) != RADIX_INDEX(old));
- BUG_ON(HEAP_INDEX(vma) != HEAP_INDEX(old));
-
- vma->shared.vm_set.head = NULL;
- vma->shared.vm_set.parent = NULL;
-
- if (!old->shared.vm_set.parent)
- list_add(&vma->shared.vm_set.list,
- &old->shared.vm_set.list);
- else if (old->shared.vm_set.head)
- list_add_tail(&vma->shared.vm_set.list,
- &old->shared.vm_set.head->shared.vm_set.list);
- else {
- INIT_LIST_HEAD(&vma->shared.vm_set.list);
- vma->shared.vm_set.head = old;
- old->shared.vm_set.head = vma;
- }
-}
-
-void vma_prio_tree_insert(struct vm_area_struct *vma,
- struct prio_tree_root *root)
-{
- struct prio_tree_node *ptr;
- struct vm_area_struct *old;
-
- vma->shared.vm_set.head = NULL;
-
- ptr = raw_prio_tree_insert(root, &vma->shared.prio_tree_node);
- if (ptr != (struct prio_tree_node *) &vma->shared.prio_tree_node) {
- old = prio_tree_entry(ptr, struct vm_area_struct,
- shared.prio_tree_node);
- vma_prio_tree_add(vma, old);
- }
-}
-
-void vma_prio_tree_remove(struct vm_area_struct *vma,
- struct prio_tree_root *root)
-{
- struct vm_area_struct *node, *head, *new_head;
-
- if (!vma->shared.vm_set.head) {
- if (!vma->shared.vm_set.parent)
- list_del_init(&vma->shared.vm_set.list);
- else
- raw_prio_tree_remove(root, &vma->shared.prio_tree_node);
- } else {
- /* Leave this BUG_ON till prio_tree patch stabilizes */
- BUG_ON(vma->shared.vm_set.head->shared.vm_set.head != vma);
- if (vma->shared.vm_set.parent) {
- head = vma->shared.vm_set.head;
- if (!list_empty(&head->shared.vm_set.list)) {
- new_head = list_entry(
- head->shared.vm_set.list.next,
- struct vm_area_struct,
- shared.vm_set.list);
- list_del_init(&head->shared.vm_set.list);
- } else
- new_head = NULL;
-
- raw_prio_tree_replace(root, &vma->shared.prio_tree_node,
- &head->shared.prio_tree_node);
- head->shared.vm_set.head = new_head;
- if (new_head)
- new_head->shared.vm_set.head = head;
-
- } else {
- node = vma->shared.vm_set.head;
- if (!list_empty(&vma->shared.vm_set.list)) {
- new_head = list_entry(
- vma->shared.vm_set.list.next,
- struct vm_area_struct,
- shared.vm_set.list);
- list_del_init(&vma->shared.vm_set.list);
- node->shared.vm_set.head = new_head;
- new_head->shared.vm_set.head = node;
- } else
- node->shared.vm_set.head = NULL;
- }
- }
-}
-
-/*
- * Helper function to enumerate vmas that map a given file page or a set of
- * contiguous file pages. The function returns vmas that at least map a single
- * page in the given range of contiguous file pages.
- */
-struct vm_area_struct *vma_prio_tree_next(struct vm_area_struct *vma,
- struct prio_tree_iter *iter)
-{
- struct prio_tree_node *ptr;
- struct vm_area_struct *next;
-
- if (!vma) {
- /*
- * First call is with NULL vma
- */
- ptr = prio_tree_next(iter);
- if (ptr) {
- next = prio_tree_entry(ptr, struct vm_area_struct,
- shared.prio_tree_node);
- prefetch(next->shared.vm_set.head);
- return next;
- } else
- return NULL;
- }
-
- if (vma->shared.vm_set.parent) {
- if (vma->shared.vm_set.head) {
- next = vma->shared.vm_set.head;
- prefetch(next->shared.vm_set.list.next);
- return next;
- }
- } else {
- next = list_entry(vma->shared.vm_set.list.next,
- struct vm_area_struct, shared.vm_set.list);
- if (!next->shared.vm_set.head) {
- prefetch(next->shared.vm_set.list.next);
- return next;
- }
- }
-
- ptr = prio_tree_next(iter);
- if (ptr) {
- next = prio_tree_entry(ptr, struct vm_area_struct,
- shared.prio_tree_node);
- prefetch(next->shared.vm_set.head);
- return next;
- } else
- return NULL;
-}