diff options
Diffstat (limited to 'libbcachefs/eytzinger.c')
| -rw-r--r-- | libbcachefs/eytzinger.c | 105 |
1 files changed, 88 insertions, 17 deletions
diff --git a/libbcachefs/eytzinger.c b/libbcachefs/eytzinger.c index 0f955c3c..2eaffe37 100644 --- a/libbcachefs/eytzinger.c +++ b/libbcachefs/eytzinger.c @@ -171,7 +171,7 @@ void eytzinger0_sort_r(void *base, size_t n, size_t size, swap_r_func_t swap_func, const void *priv) { - int i, c, r; + int i, j, k; /* called from 'sort' without swap function, let's pick the default */ if (swap_func == SWAP_WRAPPER && !((struct wrapper *)priv)->swap_func) @@ -188,17 +188,22 @@ void eytzinger0_sort_r(void *base, size_t n, size_t size, /* heapify */ for (i = n / 2 - 1; i >= 0; --i) { - for (r = i; r * 2 + 1 < n; r = c) { - c = r * 2 + 1; + /* Find the sift-down path all the way to the leaves. */ + for (j = i; k = j * 2 + 1, k + 1 < n;) + j = eytzinger0_do_cmp(base, n, size, cmp_func, priv, k, k + 1) > 0 ? k : k + 1; - if (c + 1 < n && - eytzinger0_do_cmp(base, n, size, cmp_func, priv, c, c + 1) < 0) - c++; + /* Special case for the last leaf with no sibling. */ + if (j * 2 + 2 == n) + j = j * 2 + 1; - if (eytzinger0_do_cmp(base, n, size, cmp_func, priv, r, c) >= 0) - break; + /* Backtrack to the correct location. */ + while (j != i && eytzinger0_do_cmp(base, n, size, cmp_func, priv, i, j) >= 0) + j = (j - 1) / 2; - eytzinger0_do_swap(base, n, size, swap_func, priv, r, c); + /* Shift the element into its correct place. */ + for (k = j; j != i;) { + j = (j - 1) / 2; + eytzinger0_do_swap(base, n, size, swap_func, priv, j, k); } } @@ -206,17 +211,22 @@ void eytzinger0_sort_r(void *base, size_t n, size_t size, for (i = n - 1; i > 0; --i) { eytzinger0_do_swap(base, n, size, swap_func, priv, 0, i); - for (r = 0; r * 2 + 1 < i; r = c) { - c = r * 2 + 1; + /* Find the sift-down path all the way to the leaves. */ + for (j = 0; k = j * 2 + 1, k + 1 < i;) + j = eytzinger0_do_cmp(base, n, size, cmp_func, priv, k, k + 1) > 0 ? k : k + 1; - if (c + 1 < i && - eytzinger0_do_cmp(base, n, size, cmp_func, priv, c, c + 1) < 0) - c++; + /* Special case for the last leaf with no sibling. */ + if (j * 2 + 2 == i) + j = j * 2 + 1; - if (eytzinger0_do_cmp(base, n, size, cmp_func, priv, r, c) >= 0) - break; + /* Backtrack to the correct location. */ + while (j && eytzinger0_do_cmp(base, n, size, cmp_func, priv, 0, j) >= 0) + j = (j - 1) / 2; - eytzinger0_do_swap(base, n, size, swap_func, priv, r, c); + /* Shift the element into its correct place. */ + for (k = j; j;) { + j = (j - 1) / 2; + eytzinger0_do_swap(base, n, size, swap_func, priv, j, k); } } } @@ -232,3 +242,64 @@ void eytzinger0_sort(void *base, size_t n, size_t size, return eytzinger0_sort_r(base, n, size, _CMP_WRAPPER, SWAP_WRAPPER, &w); } + +#if 0 +#include <linux/slab.h> +#include <linux/random.h> +#include <linux/ktime.h> + +static u64 cmp_count; + +static int mycmp(const void *a, const void *b) +{ + u32 _a = *(u32 *)a; + u32 _b = *(u32 *)b; + + cmp_count++; + if (_a < _b) + return -1; + else if (_a > _b) + return 1; + else + return 0; +} + +static int test(void) +{ + size_t N, i; + ktime_t start, end; + s64 delta; + u32 *arr; + + for (N = 10000; N <= 100000; N += 10000) { + arr = kmalloc_array(N, sizeof(u32), GFP_KERNEL); + cmp_count = 0; + + for (i = 0; i < N; i++) + arr[i] = get_random_u32(); + + start = ktime_get(); + eytzinger0_sort(arr, N, sizeof(u32), mycmp, NULL); + end = ktime_get(); + + delta = ktime_us_delta(end, start); + printk(KERN_INFO "time: %lld\n", delta); + printk(KERN_INFO "comparisons: %lld\n", cmp_count); + + u32 prev = 0; + + eytzinger0_for_each(i, N) { + if (prev > arr[i]) + goto err; + prev = arr[i]; + } + + kfree(arr); + } + return 0; + +err: + kfree(arr); + return -1; +} +#endif |