ee36c709c3
perf: 2.75x faster ddt_entry_compare()
First 256bits of ddt_key_t is a block checksum, which are expected
to be close to random data. Hence, on average, comparison only needs to
look at first few bytes of the keys. To reduce number of conditional
jump instructions, the result is computed as: sign(memcmp(k1, k2)).
Sign of an integer 'a' can be obtained as: `(0 < a) - (a < 0)` := {-1, 0, 1} ,
which is computed efficiently. Synthetic performance evaluation of
original and new algorithm over 1G random keys on 2.6GHz Intel(R) Xeon(R)
CPU E5-2660 v3:
old 6.85789 s
new 2.49089 s
perf: 2.8x faster vdev_queue_offset_compare() and vdev_queue_timestamp_compare()
Compute the result directly instead of using conditionals
perf: zfs_range_compare()
Speedup between 1.1x - 2.5x, depending on compiler version and
optimization level.
perf: spa_error_entry_compare()
`bcmp()` is not suitable for comparator use. Use `memcmp()` instead.
perf: 2.8x faster metaslab_compare() and metaslab_rangesize_compare()
perf: 2.8x faster zil_bp_compare()
perf: 2.8x faster mze_compare()
perf: faster dbuf_compare()
perf: faster compares in spa_misc
perf: 2.8x faster layout_hash_compare()
perf: 2.8x faster space_reftree_compare()
perf: libzfs: faster avl tree comparators
perf: guid_compare()
perf: dsl_deadlist_compare()
perf: perm_set_compare()
perf: 2x faster range_tree_seg_compare()
perf: faster unique_compare()
perf: faster vdev_cache _compare()
perf: faster vdev_uberblock_compare()
perf: faster fuid _compare()
perf: faster zfs_znode_hold_compare()
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Signed-off-by: Richard Elling <richard.elling@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #5033
326 lines
9.2 KiB
C
326 lines
9.2 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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/*
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* Copyright (c) 2014 by Delphix. All rights reserved.
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*/
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#ifndef _AVL_H
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#define _AVL_H
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/*
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* This is a private header file. Applications should not directly include
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* this file.
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <sys/types.h>
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#include <sys/avl_impl.h>
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/*
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* This is a generic implementation of AVL trees for use in the Solaris kernel.
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* The interfaces provide an efficient way of implementing an ordered set of
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* data structures.
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*
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* AVL trees provide an alternative to using an ordered linked list. Using AVL
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* trees will usually be faster, however they requires more storage. An ordered
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* linked list in general requires 2 pointers in each data structure. The
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* AVL tree implementation uses 3 pointers. The following chart gives the
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* approximate performance of operations with the different approaches:
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*
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* Operation Link List AVL tree
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* --------- -------- --------
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* lookup O(n) O(log(n))
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*
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* insert 1 node constant constant
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*
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* delete 1 node constant between constant and O(log(n))
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*
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* delete all nodes O(n) O(n)
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*
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* visit the next
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* or prev node constant between constant and O(log(n))
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*
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*
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* The data structure nodes are anchored at an "avl_tree_t" (the equivalent
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* of a list header) and the individual nodes will have a field of
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* type "avl_node_t" (corresponding to list pointers).
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*
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* The type "avl_index_t" is used to indicate a position in the list for
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* certain calls.
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*
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* The usage scenario is generally:
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*
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* 1. Create the list/tree with: avl_create()
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*
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* followed by any mixture of:
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*
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* 2a. Insert nodes with: avl_add(), or avl_find() and avl_insert()
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*
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* 2b. Visited elements with:
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* avl_first() - returns the lowest valued node
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* avl_last() - returns the highest valued node
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* AVL_NEXT() - given a node go to next higher one
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* AVL_PREV() - given a node go to previous lower one
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*
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* 2c. Find the node with the closest value either less than or greater
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* than a given value with avl_nearest().
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*
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* 2d. Remove individual nodes from the list/tree with avl_remove().
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*
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* and finally when the list is being destroyed
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*
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* 3. Use avl_destroy_nodes() to quickly process/free up any remaining nodes.
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* Note that once you use avl_destroy_nodes(), you can no longer
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* use any routine except avl_destroy_nodes() and avl_destoy().
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*
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* 4. Use avl_destroy() to destroy the AVL tree itself.
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*
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* Any locking for multiple thread access is up to the user to provide, just
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* as is needed for any linked list implementation.
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*/
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/*
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* AVL comparator helpers
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*/
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#define AVL_ISIGN(a) (((a) > 0) - ((a) < 0))
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#define AVL_CMP(a, b) (((a) > (b)) - ((a) < (b)))
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#define AVL_PCMP(a, b) \
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(((uintptr_t)(a) > (uintptr_t)(b)) - ((uintptr_t)(a) < (uintptr_t)(b)))
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/*
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* Type used for the root of the AVL tree.
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*/
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typedef struct avl_tree avl_tree_t;
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/*
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* The data nodes in the AVL tree must have a field of this type.
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*/
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typedef struct avl_node avl_node_t;
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/*
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* An opaque type used to locate a position in the tree where a node
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* would be inserted.
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*/
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typedef uintptr_t avl_index_t;
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/*
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* Direction constants used for avl_nearest().
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*/
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#define AVL_BEFORE (0)
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#define AVL_AFTER (1)
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/*
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* Prototypes
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*
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* Where not otherwise mentioned, "void *" arguments are a pointer to the
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* user data structure which must contain a field of type avl_node_t.
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*
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* Also assume the user data structures looks like:
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* stuct my_type {
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* ...
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* avl_node_t my_link;
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* ...
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* };
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*/
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/*
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* Initialize an AVL tree. Arguments are:
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*
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* tree - the tree to be initialized
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* compar - function to compare two nodes, it must return exactly: -1, 0, or +1
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* -1 for <, 0 for ==, and +1 for >
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* size - the value of sizeof(struct my_type)
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* offset - the value of OFFSETOF(struct my_type, my_link)
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*/
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extern void avl_create(avl_tree_t *tree,
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int (*compar) (const void *, const void *), size_t size, size_t offset);
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/*
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* Find a node with a matching value in the tree. Returns the matching node
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* found. If not found, it returns NULL and then if "where" is not NULL it sets
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* "where" for use with avl_insert() or avl_nearest().
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*
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* node - node that has the value being looked for
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* where - position for use with avl_nearest() or avl_insert(), may be NULL
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*/
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extern void *avl_find(avl_tree_t *tree, const void *node, avl_index_t *where);
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/*
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* Insert a node into the tree.
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*
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* node - the node to insert
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* where - position as returned from avl_find()
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*/
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extern void avl_insert(avl_tree_t *tree, void *node, avl_index_t where);
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/*
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* Insert "new_data" in "tree" in the given "direction" either after
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* or before the data "here".
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*
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* This might be useful for avl clients caching recently accessed
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* data to avoid doing avl_find() again for insertion.
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*
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* new_data - new data to insert
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* here - existing node in "tree"
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* direction - either AVL_AFTER or AVL_BEFORE the data "here".
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*/
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extern void avl_insert_here(avl_tree_t *tree, void *new_data, void *here,
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int direction);
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/*
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* Return the first or last valued node in the tree. Will return NULL
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* if the tree is empty.
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*
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*/
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extern void *avl_first(avl_tree_t *tree);
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extern void *avl_last(avl_tree_t *tree);
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/*
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* Return the next or previous valued node in the tree.
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* AVL_NEXT() will return NULL if at the last node.
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* AVL_PREV() will return NULL if at the first node.
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*
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* node - the node from which the next or previous node is found
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*/
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#define AVL_NEXT(tree, node) avl_walk(tree, node, AVL_AFTER)
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#define AVL_PREV(tree, node) avl_walk(tree, node, AVL_BEFORE)
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/*
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* Find the node with the nearest value either greater or less than
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* the value from a previous avl_find(). Returns the node or NULL if
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* there isn't a matching one.
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*
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* where - position as returned from avl_find()
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* direction - either AVL_BEFORE or AVL_AFTER
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*
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* EXAMPLE get the greatest node that is less than a given value:
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*
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* avl_tree_t *tree;
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* struct my_data look_for_value = {....};
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* struct my_data *node;
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* struct my_data *less;
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* avl_index_t where;
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*
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* node = avl_find(tree, &look_for_value, &where);
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* if (node != NULL)
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* less = AVL_PREV(tree, node);
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* else
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* less = avl_nearest(tree, where, AVL_BEFORE);
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*/
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extern void *avl_nearest(avl_tree_t *tree, avl_index_t where, int direction);
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/*
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* Add a single node to the tree.
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* The node must not be in the tree, and it must not
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* compare equal to any other node already in the tree.
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*
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* node - the node to add
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*/
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extern void avl_add(avl_tree_t *tree, void *node);
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/*
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* Remove a single node from the tree. The node must be in the tree.
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*
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* node - the node to remove
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*/
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extern void avl_remove(avl_tree_t *tree, void *node);
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/*
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* Reinsert a node only if its order has changed relative to its nearest
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* neighbors. To optimize performance avl_update_lt() checks only the previous
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* node and avl_update_gt() checks only the next node. Use avl_update_lt() and
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* avl_update_gt() only if you know the direction in which the order of the
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* node may change.
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*/
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extern boolean_t avl_update(avl_tree_t *, void *);
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extern boolean_t avl_update_lt(avl_tree_t *, void *);
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extern boolean_t avl_update_gt(avl_tree_t *, void *);
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/*
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* Swaps the contents of the two trees.
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*/
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extern void avl_swap(avl_tree_t *tree1, avl_tree_t *tree2);
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/*
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* Return the number of nodes in the tree
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*/
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extern ulong_t avl_numnodes(avl_tree_t *tree);
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/*
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* Return B_TRUE if there are zero nodes in the tree, B_FALSE otherwise.
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*/
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extern boolean_t avl_is_empty(avl_tree_t *tree);
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/*
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* Used to destroy any remaining nodes in a tree. The cookie argument should
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* be initialized to NULL before the first call. Returns a node that has been
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* removed from the tree and may be free()'d. Returns NULL when the tree is
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* empty.
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*
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* Once you call avl_destroy_nodes(), you can only continuing calling it and
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* finally avl_destroy(). No other AVL routines will be valid.
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*
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* cookie - a "void *" used to save state between calls to avl_destroy_nodes()
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*
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* EXAMPLE:
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* avl_tree_t *tree;
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* struct my_data *node;
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* void *cookie;
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*
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* cookie = NULL;
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* while ((node = avl_destroy_nodes(tree, &cookie)) != NULL)
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* free(node);
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* avl_destroy(tree);
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*/
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extern void *avl_destroy_nodes(avl_tree_t *tree, void **cookie);
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/*
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* Final destroy of an AVL tree. Arguments are:
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*
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* tree - the empty tree to destroy
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*/
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extern void avl_destroy(avl_tree_t *tree);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _AVL_H */
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