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| author | keios <keios.cn@gmail.com> | 2006-10-03 01:13:49 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-03 08:03:41 -0700 |
| commit | d3717bdf8f08a0e1039158c8bab2c24d20f492b6 (patch) | |
| tree | 9c8617cb3f58faace4941a0aa09ea1820d287b7c /lib/sort.c | |
| parent | ffc5089196446c08d9a005cf0dd7cab18d119606 (diff) | |
| download | lwn-d3717bdf8f08a0e1039158c8bab2c24d20f492b6.tar.gz lwn-d3717bdf8f08a0e1039158c8bab2c24d20f492b6.zip | |
[PATCH] low performance of lib/sort.c
It is a non-standard heap-sort algorithm implementation because the index
of child node is wrong . The sort function still outputs right result, but
the performance is O( n * ( log(n) + 1 ) ) , about 10% ~ 20% worse than
standard algorithm.
Signed-off-by: keios <keios.cn@gmail.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Acked-by: Zou Nan hai <nanhai.zou@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'lib/sort.c')
| -rw-r--r-- | lib/sort.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/lib/sort.c b/lib/sort.c index 5f3b51ffa1dc..488788b341cb 100644 --- a/lib/sort.c +++ b/lib/sort.c @@ -49,15 +49,15 @@ void sort(void *base, size_t num, size_t size, void (*swap)(void *, void *, int size)) { /* pre-scale counters for performance */ - int i = (num/2) * size, n = num * size, c, r; + int i = (num/2 - 1) * size, n = num * size, c, r; if (!swap) swap = (size == 4 ? u32_swap : generic_swap); /* heapify */ for ( ; i >= 0; i -= size) { - for (r = i; r * 2 < n; r = c) { - c = r * 2; + for (r = i; r * 2 + size < n; r = c) { + c = r * 2 + size; if (c < n - size && cmp(base + c, base + c + size) < 0) c += size; if (cmp(base + r, base + c) >= 0) @@ -69,8 +69,8 @@ void sort(void *base, size_t num, size_t size, /* sort */ for (i = n - size; i >= 0; i -= size) { swap(base, base + i, size); - for (r = 0; r * 2 < i; r = c) { - c = r * 2; + for (r = 0; r * 2 + size < i; r = c) { + c = r * 2 + size; if (c < i - size && cmp(base + c, base + c + size) < 0) c += size; if (cmp(base + r, base + c) >= 0) |