c/mirror_zfs
1
0
Fork 0
mirror of https://git.proxmox.com/git/mirror_zfs.git synced 2026-05-27 04:32:16 +03:00
Code Issues Packages Projects Releases Wiki Activity

btree: Implement faster binary search algorithm

Browse Source 
This implements a binary search algorithm for B-Trees that reduces
branching to the absolute minimum necessary for a binary search
algorithm. It also enables the compiler to inline the comparator to
ensure that the only slowdown when doing binary search is from waiting
for memory accesses. Additionally, it instructs the compiler to unroll
the loop, which gives an additional 40% improve with Clang and 8%
improvement with GCC.

Consumers must opt into using the faster algorithm. At present, only
B-Trees used inside kernel code have been modified to use the faster
algorithm.

Micro-benchmarks suggest that this can improve binary search performance
by up to 3.5 times when compiling with Clang 16 and up to 1.9 times when
compiling with GCC 12.2.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14866
This commit is contained in:
Richard Yao
2023-05-26 13:03:12 -04:00
committed by GitHub
parent bb736d98d1
commit 677c6f8457
10 changed files with 154 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/range_tree.c
+17 -1
View File
@@ -151,6 +151,7 @@ range_tree_stat_decr(range_tree_t *rt, range_seg_t *rs)
rt->rt_histogram[idx]--;
}
__attribute__((always_inline)) inline
static int
range_tree_seg32_compare(const void *x1, const void *x2)
{
@@ -163,6 +164,7 @@ range_tree_seg32_compare(const void *x1, const void *x2)
return ((r1->rs_start >= r2->rs_end) - (r1->rs_end <= r2->rs_start));
}
__attribute__((always_inline)) inline
static int
range_tree_seg64_compare(const void *x1, const void *x2)
{
@@ -175,6 +177,7 @@ range_tree_seg64_compare(const void *x1, const void *x2)
return ((r1->rs_start >= r2->rs_end) - (r1->rs_end <= r2->rs_start));
}
__attribute__((always_inline)) inline
static int
range_tree_seg_gap_compare(const void *x1, const void *x2)
{
@@ -187,6 +190,15 @@ range_tree_seg_gap_compare(const void *x1, const void *x2)
return ((r1->rs_start >= r2->rs_end) - (r1->rs_end <= r2->rs_start));
}
ZFS_BTREE_FIND_IN_BUF_FUNC(range_tree_seg32_find_in_buf, range_seg32_t,
range_tree_seg32_compare)
ZFS_BTREE_FIND_IN_BUF_FUNC(range_tree_seg64_find_in_buf, range_seg64_t,
range_tree_seg64_compare)
ZFS_BTREE_FIND_IN_BUF_FUNC(range_tree_seg_gap_find_in_buf, range_seg_gap_t,
range_tree_seg_gap_compare)
range_tree_t *
range_tree_create_gap(const range_tree_ops_t *ops, range_seg_type_t type,
void *arg, uint64_t start, uint64_t shift, uint64_t gap)
@@ -197,23 +209,27 @@ range_tree_create_gap(const range_tree_ops_t *ops, range_seg_type_t type,
ASSERT3U(type, <=, RANGE_SEG_NUM_TYPES);
size_t size;
int (*compare) (const void *, const void *);
bt_find_in_buf_f bt_find;
switch (type) {
case RANGE_SEG32:
size = sizeof (range_seg32_t);
compare = range_tree_seg32_compare;
bt_find = range_tree_seg32_find_in_buf;
break;
case RANGE_SEG64:
size = sizeof (range_seg64_t);
compare = range_tree_seg64_compare;
bt_find = range_tree_seg64_find_in_buf;
break;
case RANGE_SEG_GAP:
size = sizeof (range_seg_gap_t);
compare = range_tree_seg_gap_compare;
bt_find = range_tree_seg_gap_find_in_buf;
break;
default:
panic("Invalid range seg type %d", type);
}
zfs_btree_create(&rt->rt_root, compare, size);
zfs_btree_create(&rt->rt_root, compare, bt_find, size);
rt->rt_ops = ops;
rt->rt_gap = gap;