Check in an intial implementation of radix tree implementation to replace

the vm object pages splay.

TODO:
- Handle differently the negative keys for having smaller depth
  index nodes (negative keys caming from indirect blocks)
- Fix the get_node() by having support for a low reserved objects
  directly from UMA
- Implement the lookup_le and re-enable VM_NRESERVELEVEL = 1
- Try to rework the superpage splay of idle pages and the cache splay
  for every vm object in order to regain space on vm_page structure
- Verify performance and improve them (likely by having consumers to deal
  with several ranges of pages manually?)

Obtained from:	jeff, Mayur Shardul (GSoC 2009)

1 files changed, 64 insertions, 0 deletions

diff --git a/sys/vm/vm_radix.h b/sys/vm/vm_radix.h
new file mode 100644
index 0000000..645f4cd
--- /dev/null
+++ b/sys/vm/vm_radix.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+
+#ifndef _VM_RADIX_H_
+#define _VM_RADIX_H_
+
+#include <sys/queue.h>
+
+/* Default values of the tree parameters */
+#define	VM_RADIX_WIDTH	5
+#define	VM_RADIX_COUNT	(1 << VM_RADIX_WIDTH)
+#define	VM_RADIX_MASK	(VM_RADIX_COUNT - 1)
+#define	VM_RADIX_LIMIT	howmany((sizeof(vm_pindex_t) * NBBY), VM_RADIX_WIDTH)
+
+/* Calculates maximum value for a tree of height h. */
+#define	VM_RADIX_MAX(h)							\
+	    ((h) == VM_RADIX_LIMIT ? ((vm_pindex_t)-1) :		\
+	    (((vm_pindex_t)1 << ((h) * VM_RADIX_WIDTH)) - 1))
+
+struct vm_radix_node {
+	SLIST_ENTRY(vm_radix_node) next;
+	void 		*rn_child[VM_RADIX_COUNT];	/* child nodes. */
+    	uint16_t	rn_count;			/* Valid children. */
+};
+
+struct vm_radix {
+	struct 	vm_radix_node *rt_root; 	/* Root node. */
+	int 	rt_height; 			/* Number of levels + 1. */
+};
+
+int 	vm_radix_insert(struct vm_radix *, vm_pindex_t, void *);
+void	*vm_radix_remove(struct vm_radix *, vm_pindex_t);
+void	*vm_radix_lookup(struct vm_radix *, vm_pindex_t);
+int	vm_radix_lookupn(struct vm_radix *rtree, vm_pindex_t start,
+	    vm_pindex_t end, void **out, int cnt, vm_pindex_t *next);
+void	*vm_radix_lookup_ge(struct vm_radix *, vm_pindex_t);
+void	*vm_radix_lookup_le(struct vm_radix *, vm_pindex_t);
+void 	vm_radix_shrink(struct vm_radix *);
+
+#endif /* !_VM_RADIX_H_ */