[PATCH] low performance of lib/sort.c (d3717bdf) · Commits · 戴 / test

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>

lib/sort.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -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)

Admin message