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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
113 lines
2.5 KiB
C
113 lines
2.5 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 2007 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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#include <sys/zfs_context.h>
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#include <sys/avl.h>
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#include <sys/unique.h>
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static avl_tree_t unique_avl;
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static kmutex_t unique_mtx;
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typedef struct unique {
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avl_node_t un_link;
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uint64_t un_value;
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} unique_t;
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#define UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1)
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static int
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unique_compare(const void *a, const void *b)
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{
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const unique_t *una = (const unique_t *)a;
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const unique_t *unb = (const unique_t *)b;
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return (AVL_CMP(una->un_value, unb->un_value));
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}
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void
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unique_init(void)
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{
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avl_create(&unique_avl, unique_compare,
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sizeof (unique_t), offsetof(unique_t, un_link));
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mutex_init(&unique_mtx, NULL, MUTEX_DEFAULT, NULL);
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}
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void
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unique_fini(void)
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{
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avl_destroy(&unique_avl);
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mutex_destroy(&unique_mtx);
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}
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uint64_t
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unique_create(void)
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{
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uint64_t value = unique_insert(0);
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unique_remove(value);
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return (value);
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}
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uint64_t
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unique_insert(uint64_t value)
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{
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avl_index_t idx;
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unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP);
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un->un_value = value;
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mutex_enter(&unique_mtx);
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while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK ||
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avl_find(&unique_avl, un, &idx)) {
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mutex_exit(&unique_mtx);
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(void) random_get_pseudo_bytes((void*)&un->un_value,
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sizeof (un->un_value));
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un->un_value &= UNIQUE_MASK;
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mutex_enter(&unique_mtx);
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}
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avl_insert(&unique_avl, un, idx);
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mutex_exit(&unique_mtx);
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return (un->un_value);
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}
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void
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unique_remove(uint64_t value)
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{
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unique_t un_tofind;
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unique_t *un;
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un_tofind.un_value = value;
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mutex_enter(&unique_mtx);
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un = avl_find(&unique_avl, &un_tofind, NULL);
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if (un != NULL) {
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avl_remove(&unique_avl, un);
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kmem_free(un, sizeof (unique_t));
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}
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mutex_exit(&unique_mtx);
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}
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