prio_tree: remove

After both prio_tree users have been converted to use red-black trees,
there is no need to keep around the prio tree library anymore.
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>

Documentation/00-INDEX

@@ -270,8 +270,6 @@ preempt-locking.txt
 	- info on locking under a preemptive kernel.
 printk-formats.txt
 	- how to get printk format specifiers right
-prio_tree.txt
-	- info on radix-priority-search-tree use for indexing vmas.
 ramoops.txt
 	- documentation of the ramoops oops/panic logging module.
 rbtree.txt

Documentation/prio_tree.txt

-The prio_tree.c code indexes vmas using 3 different indexes:
-	* heap_index  = vm_pgoff + vm_size_in_pages : end_vm_pgoff
-	* radix_index = vm_pgoff : start_vm_pgoff
-	* size_index = vm_size_in_pages
-
-A regular radix-priority-search-tree indexes vmas using only heap_index and
-radix_index. The conditions for indexing are:
-	* ->heap_index >= ->left->heap_index &&
-		->heap_index >= ->right->heap_index
-	* if (->heap_index == ->left->heap_index)
-		then ->radix_index < ->left->radix_index;
-	* if (->heap_index == ->right->heap_index)
-		then ->radix_index < ->right->radix_index;
-	* nodes are hashed to left or right subtree using radix_index
-	  similar to a pure binary radix tree.
-
-A regular radix-priority-search-tree helps to store and query
-intervals (vmas). However, a regular radix-priority-search-tree is only
-suitable for storing vmas with different radix indices (vm_pgoff).
-
-Therefore, the prio_tree.c extends the regular radix-priority-search-tree
-to handle many vmas with the same vm_pgoff. Such vmas are handled in
-2 different ways: 1) All vmas with the same radix _and_ heap indices are
-linked using vm_set.list, 2) if there are many vmas with the same radix
-index, but different heap indices and if the regular radix-priority-search
-tree cannot index them all, we build an overflow-sub-tree that indexes such
-vmas using heap and size indices instead of heap and radix indices. For
-example, in the figure below some vmas with vm_pgoff = 0 (zero) are
-indexed by regular radix-priority-search-tree whereas others are pushed
-into an overflow-subtree. Note that all vmas in an overflow-sub-tree have
-the same vm_pgoff (radix_index) and if necessary we build different
-overflow-sub-trees to handle each possible radix_index. For example,
-in figure we have 3 overflow-sub-trees corresponding to radix indices
-0, 2, and 4.
-
-In the final tree the first few (prio_tree_root->index_bits) levels
-are indexed using heap and radix indices whereas the overflow-sub-trees below
-those levels (i.e. levels prio_tree_root->index_bits + 1 and higher) are
-indexed using heap and size indices. In overflow-sub-trees the size_index
-is used for hashing the nodes to appropriate places.
-
-Now, an example prio_tree:
-
-  vmas are represented [radix_index, size_index, heap_index]
-                 i.e., [start_vm_pgoff, vm_size_in_pages, end_vm_pgoff]
-
-level  prio_tree_root->index_bits = 3
------
-												_
-  0			 				[0,7,7]					 |
-  							/     \					 |
-				      ------------------       ------------			 |     Regular
-  				     /					   \			 |  radix priority
-  1		 		[1,6,7]					  [4,3,7]		 |   search tree
-  				/     \					  /     \		 |
-			 -------       -----			    ------       -----		 |  heap-and-radix
-			/		    \			   /		      \		 |      indexed
-  2		    [0,6,6]	 	   [2,5,7]		[5,2,7]		    [6,1,7]	 |
-		    /     \		   /     \		/     \		    /     \	 |
-  3		[0,5,5]	[1,5,6]		[2,4,6]	[3,4,7]	    [4,2,6] [5,1,6]	[6,0,6]	[7,0,7]	 |
-		   /			   /		       /		   		_
-                  /		          /		      /					_
-  4	      [0,4,4]		      [2,3,5]		   [4,1,5]				 |
-  		 /			 /		      /					 |
-  5	     [0,3,3]		     [2,2,4]		  [4,0,4]				 |  Overflow-sub-trees
-  		/			/							 |
-  6	    [0,2,2]		    [2,1,3]							 |    heap-and-size
-  	       /		       /							 |       indexed
-  7	   [0,1,1]		   [2,0,2]							 |
-  	      /											 |
-  8	  [0,0,0]										 |
-  												_
-
-Note that we use prio_tree_root->index_bits to optimize the height
-of the heap-and-radix indexed tree. Since prio_tree_root->index_bits is
-set according to the maximum end_vm_pgoff mapped, we are sure that all
-bits (in vm_pgoff) above prio_tree_root->index_bits are 0 (zero). Therefore,
-we only use the first prio_tree_root->index_bits as radix_index.
-Whenever index_bits is increased in prio_tree_expand, we shuffle the tree
-to make sure that the first prio_tree_root->index_bits levels of the tree
-is indexed properly using heap and radix indices.
-
-We do not optimize the height of overflow-sub-trees using index_bits.
-The reason is: there can be many such overflow-sub-trees and all of
-them have to be suffled whenever the index_bits increases. This may involve
-walking the whole prio_tree in prio_tree_insert->prio_tree_expand code
-path which is not desirable. Hence, we do not optimize the height of the
-heap-and-size indexed overflow-sub-trees using prio_tree->index_bits.
-Instead the overflow sub-trees are indexed using full BITS_PER_LONG bits
-of size_index. This may lead to skewed sub-trees because most of the
-higher significant bits of the size_index are likely to be 0 (zero). In
-the example above, all 3 overflow-sub-trees are skewed. This may marginally
-affect the performance. However, processes rarely map many vmas with the
-same start_vm_pgoff but different end_vm_pgoffs. Therefore, we normally
-do not require overflow-sub-trees to index all vmas.
-
-From the above discussion it is clear that the maximum height of
-a prio_tree can be prio_tree_root->index_bits + BITS_PER_LONG.
-However, in most of the common cases we do not need overflow-sub-trees,
-so the tree height in the common cases will be prio_tree_root->index_bits.
-
-It is fair to mention here that the prio_tree_root->index_bits
-is increased on demand, however, the index_bits is not decreased when
-vmas are removed from the prio_tree. That's tricky to do. Hence, it's
-left as a home work problem.
-
-

include/linux/prio_tree.h

-#ifndef _LINUX_PRIO_TREE_H
-#define _LINUX_PRIO_TREE_H
-
-/*
- * K&R 2nd ed. A8.3 somewhat obliquely hints that initial sequences of struct
- * fields with identical types should end up at the same location. We'll use
- * this until we can scrap struct raw_prio_tree_node.
- *
- * Note: all this could be done more elegantly by using unnamed union/struct
- * fields. However, gcc 2.95.3 and apparently also gcc 3.0.4 don't support this
- * language extension.
- */
-
-struct raw_prio_tree_node {
-	struct prio_tree_node	*left;
-	struct prio_tree_node	*right;
-	struct prio_tree_node	*parent;
-};
-
-struct prio_tree_node {
-	struct prio_tree_node	*left;
-	struct prio_tree_node	*right;
-	struct prio_tree_node	*parent;
-	unsigned long		start;
-	unsigned long		last;	/* last location _in_ interval */
-};
-
-struct prio_tree_root {
-	struct prio_tree_node	*prio_tree_node;
-	unsigned short 		index_bits;
-	unsigned short		raw;
-		/*
-		 * 0: nodes are of type struct prio_tree_node
-		 * 1: nodes are of type raw_prio_tree_node
-		 */
-};
-
-struct prio_tree_iter {
-	struct prio_tree_node	*cur;
-	unsigned long		mask;
-	unsigned long		value;
-	int			size_level;
-
-	struct prio_tree_root	*root;
-	pgoff_t			r_index;
-	pgoff_t			h_index;
-};
-
-static inline void prio_tree_iter_init(struct prio_tree_iter *iter,
-		struct prio_tree_root *root, pgoff_t r_index, pgoff_t h_index)
-{
-	iter->root = root;
-	iter->r_index = r_index;
-	iter->h_index = h_index;
-	iter->cur = NULL;
-}
-
-#define __INIT_PRIO_TREE_ROOT(ptr, _raw)	\
-do {					\
-	(ptr)->prio_tree_node = NULL;	\
-	(ptr)->index_bits = 1;		\
-	(ptr)->raw = (_raw);		\
-} while (0)
-
-#define INIT_PRIO_TREE_ROOT(ptr)	__INIT_PRIO_TREE_ROOT(ptr, 0)
-#define INIT_RAW_PRIO_TREE_ROOT(ptr)	__INIT_PRIO_TREE_ROOT(ptr, 1)
-
-#define INIT_PRIO_TREE_NODE(ptr)				\
-do {								\
-	(ptr)->left = (ptr)->right = (ptr)->parent = (ptr);	\
-} while (0)
-
-#define INIT_PRIO_TREE_ITER(ptr)	\
-do {					\
-	(ptr)->cur = NULL;		\
-	(ptr)->mask = 0UL;		\
-	(ptr)->value = 0UL;		\
-	(ptr)->size_level = 0;		\
-} while (0)
-
-#define prio_tree_entry(ptr, type, member) \
-       ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
-
-static inline int prio_tree_empty(const struct prio_tree_root *root)
-{
-	return root->prio_tree_node == NULL;
-}
-
-static inline int prio_tree_root(const struct prio_tree_node *node)
-{
-	return node->parent == node;
-}
-
-static inline int prio_tree_left_empty(const struct prio_tree_node *node)
-{
-	return node->left == node;
-}
-
-static inline int prio_tree_right_empty(const struct prio_tree_node *node)
-{
-	return node->right == node;
-}
-
-
-struct prio_tree_node *prio_tree_replace(struct prio_tree_root *root,
-                struct prio_tree_node *old, struct prio_tree_node *node);
-struct prio_tree_node *prio_tree_insert(struct prio_tree_root *root,
-                struct prio_tree_node *node);
-void prio_tree_remove(struct prio_tree_root *root, struct prio_tree_node *node);
-struct prio_tree_node *prio_tree_next(struct prio_tree_iter *iter);
-
-#define raw_prio_tree_replace(root, old, node) \
-	prio_tree_replace(root, (struct prio_tree_node *) (old), \
-	    (struct prio_tree_node *) (node))
-#define raw_prio_tree_insert(root, node) \
-	prio_tree_insert(root, (struct prio_tree_node *) (node))
-#define raw_prio_tree_remove(root, node) \
-	prio_tree_remove(root, (struct prio_tree_node *) (node))
-
-#endif /* _LINUX_PRIO_TREE_H */

init/main.c

@@ -86,7 +86,6 @@ extern void init_IRQ(void);
 extern void fork_init(unsigned long);
 extern void mca_init(void);
 extern void sbus_init(void);
-extern void prio_tree_init(void);
 extern void radix_tree_init(void);
 #ifndef CONFIG_DEBUG_RODATA
 static inline void mark_rodata_ro(void) { }
@@ -547,7 +546,6 @@ asmlinkage void __init start_kernel(void)
 	/* init some links before init_ISA_irqs() */
 	early_irq_init();
 	init_IRQ();
-	prio_tree_init();
 	init_timers();
 	hrtimers_init();
 	softirq_init();

lib/Kconfig.debug

@@ -1289,12 +1289,6 @@ config RBTREE_TEST
 	  A benchmark measuring the performance of the rbtree library.
 	  Also includes rbtree invariant checks.
 
-config PRIO_TREE_TEST
-	tristate "Prio tree test"
-	depends on m && DEBUG_KERNEL
-	help
-	  A benchmark measuring the performance of the prio tree library
-
 config INTERVAL_TREE_TEST
 	tristate "Interval tree test"
 	depends on m && DEBUG_KERNEL

lib/Makefile

@@ -9,7 +9,7 @@ endif
 
 lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 rbtree.o radix-tree.o dump_stack.o timerqueue.o\
-	 idr.o int_sqrt.o extable.o prio_tree.o \
+	 idr.o int_sqrt.o extable.o \
 	 sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o
@@ -141,7 +141,6 @@ $(foreach file, $(libfdt_files), \
 lib-$(CONFIG_LIBFDT) += $(libfdt_files)
 
 obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o
-obj-$(CONFIG_PRIO_TREE_TEST) += prio_tree_test.o
 obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
 
 interval_tree_test-objs := interval_tree_test_main.o interval_tree.o

lib/prio_tree_test.c

-#include <linux/module.h>
-#include <linux/prio_tree.h>
-#include <linux/random.h>
-#include <asm/timex.h>
-
-#define NODES        100
-#define PERF_LOOPS   100000
-#define SEARCHES     100
-#define SEARCH_LOOPS 10000
-
-static struct prio_tree_root root;
-static struct prio_tree_node nodes[NODES];
-static u32 queries[SEARCHES];
-
-static struct rnd_state rnd;
-
-static inline unsigned long
-search(unsigned long query, struct prio_tree_root *root)
-{
-	struct prio_tree_iter iter;
-	unsigned long results = 0;
-
-	prio_tree_iter_init(&iter, root, query, query);
-	while (prio_tree_next(&iter))
-		results++;
-	return results;
-}
-
-static void init(void)
-{
-	int i;
-	for (i = 0; i < NODES; i++) {
-		u32 a = prandom32(&rnd), b = prandom32(&rnd);
-		if (a <= b) {
-			nodes[i].start = a;
-			nodes[i].last = b;
-		} else {
-			nodes[i].start = b;
-			nodes[i].last = a;
-		}
-	}
-	for (i = 0; i < SEARCHES; i++)
-		queries[i] = prandom32(&rnd);
-}
-
-static int prio_tree_test_init(void)
-{
-	int i, j;
-	unsigned long results;
-	cycles_t time1, time2, time;
-
-	printk(KERN_ALERT "prio tree insert/remove");
-
-	prandom32_seed(&rnd, 3141592653589793238ULL);
-	INIT_PRIO_TREE_ROOT(&root);
-	init();
-
-	time1 = get_cycles();
-
-	for (i = 0; i < PERF_LOOPS; i++) {
-		for (j = 0; j < NODES; j++)
-			prio_tree_insert(&root, nodes + j);
-		for (j = 0; j < NODES; j++)
-			prio_tree_remove(&root, nodes + j);
-	}
-
-	time2 = get_cycles();
-	time = time2 - time1;
-
-	time = div_u64(time, PERF_LOOPS);
-	printk(" -> %llu cycles\n", (unsigned long long)time);
-
-	printk(KERN_ALERT "prio tree search");
-
-	for (j = 0; j < NODES; j++)
-		prio_tree_insert(&root, nodes + j);
-
-	time1 = get_cycles();
-
-	results = 0;
-	for (i = 0; i < SEARCH_LOOPS; i++)
-		for (j = 0; j < SEARCHES; j++)
-			results += search(queries[j], &root);
-
-	time2 = get_cycles();
-	time = time2 - time1;
-
-	time = div_u64(time, SEARCH_LOOPS);
-	results = div_u64(results, SEARCH_LOOPS);
-	printk(" -> %llu cycles (%lu results)\n",
-	       (unsigned long long)time, results);
-
-	return -EAGAIN; /* Fail will directly unload the module */
-}
-
-static void prio_tree_test_exit(void)
-{
-	printk(KERN_ALERT "test exit\n");
-}
-
-module_init(prio_tree_test_init)
-module_exit(prio_tree_test_exit)
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Michel Lespinasse");
-MODULE_DESCRIPTION("Prio Tree test");