diff options
Diffstat (limited to 'fs/bcachefs/eytzinger.c')
-rw-r--r-- | fs/bcachefs/eytzinger.c | 315 |
1 files changed, 0 insertions, 315 deletions
diff --git a/fs/bcachefs/eytzinger.c b/fs/bcachefs/eytzinger.c deleted file mode 100644 index 0e742555cb0a..000000000000 --- a/fs/bcachefs/eytzinger.c +++ /dev/null @@ -1,315 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 - -#include "eytzinger.h" - -/** - * is_aligned - is this pointer & size okay for word-wide copying? - * @base: pointer to data - * @size: size of each element - * @align: required alignment (typically 4 or 8) - * - * Returns true if elements can be copied using word loads and stores. - * The size must be a multiple of the alignment, and the base address must - * be if we do not have CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS. - * - * For some reason, gcc doesn't know to optimize "if (a & mask || b & mask)" - * to "if ((a | b) & mask)", so we do that by hand. - */ -__attribute_const__ __always_inline -static bool is_aligned(const void *base, size_t size, unsigned char align) -{ - unsigned char lsbits = (unsigned char)size; - - (void)base; -#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS - lsbits |= (unsigned char)(uintptr_t)base; -#endif - return (lsbits & (align - 1)) == 0; -} - -/** - * swap_words_32 - swap two elements in 32-bit chunks - * @a: pointer to the first element to swap - * @b: pointer to the second element to swap - * @n: element size (must be a multiple of 4) - * - * Exchange the two objects in memory. This exploits base+index addressing, - * which basically all CPUs have, to minimize loop overhead computations. - * - * For some reason, on x86 gcc 7.3.0 adds a redundant test of n at the - * bottom of the loop, even though the zero flag is still valid from the - * subtract (since the intervening mov instructions don't alter the flags). - * Gcc 8.1.0 doesn't have that problem. - */ -static void swap_words_32(void *a, void *b, size_t n) -{ - do { - u32 t = *(u32 *)(a + (n -= 4)); - *(u32 *)(a + n) = *(u32 *)(b + n); - *(u32 *)(b + n) = t; - } while (n); -} - -/** - * swap_words_64 - swap two elements in 64-bit chunks - * @a: pointer to the first element to swap - * @b: pointer to the second element to swap - * @n: element size (must be a multiple of 8) - * - * Exchange the two objects in memory. This exploits base+index - * addressing, which basically all CPUs have, to minimize loop overhead - * computations. - * - * We'd like to use 64-bit loads if possible. If they're not, emulating - * one requires base+index+4 addressing which x86 has but most other - * processors do not. If CONFIG_64BIT, we definitely have 64-bit loads, - * but it's possible to have 64-bit loads without 64-bit pointers (e.g. - * x32 ABI). Are there any cases the kernel needs to worry about? - */ -static void swap_words_64(void *a, void *b, size_t n) -{ - do { -#ifdef CONFIG_64BIT - u64 t = *(u64 *)(a + (n -= 8)); - *(u64 *)(a + n) = *(u64 *)(b + n); - *(u64 *)(b + n) = t; -#else - /* Use two 32-bit transfers to avoid base+index+4 addressing */ - u32 t = *(u32 *)(a + (n -= 4)); - *(u32 *)(a + n) = *(u32 *)(b + n); - *(u32 *)(b + n) = t; - - t = *(u32 *)(a + (n -= 4)); - *(u32 *)(a + n) = *(u32 *)(b + n); - *(u32 *)(b + n) = t; -#endif - } while (n); -} - -/** - * swap_bytes - swap two elements a byte at a time - * @a: pointer to the first element to swap - * @b: pointer to the second element to swap - * @n: element size - * - * This is the fallback if alignment doesn't allow using larger chunks. - */ -static void swap_bytes(void *a, void *b, size_t n) -{ - do { - char t = ((char *)a)[--n]; - ((char *)a)[n] = ((char *)b)[n]; - ((char *)b)[n] = t; - } while (n); -} - -/* - * The values are arbitrary as long as they can't be confused with - * a pointer, but small integers make for the smallest compare - * instructions. - */ -#define SWAP_WORDS_64 (swap_r_func_t)0 -#define SWAP_WORDS_32 (swap_r_func_t)1 -#define SWAP_BYTES (swap_r_func_t)2 -#define SWAP_WRAPPER (swap_r_func_t)3 - -struct wrapper { - cmp_func_t cmp; - swap_func_t swap_func; -}; - -/* - * The function pointer is last to make tail calls most efficient if the - * compiler decides not to inline this function. - */ -static void do_swap(void *a, void *b, size_t size, swap_r_func_t swap_func, const void *priv) -{ - if (swap_func == SWAP_WRAPPER) { - ((const struct wrapper *)priv)->swap_func(a, b, (int)size); - return; - } - - if (swap_func == SWAP_WORDS_64) - swap_words_64(a, b, size); - else if (swap_func == SWAP_WORDS_32) - swap_words_32(a, b, size); - else if (swap_func == SWAP_BYTES) - swap_bytes(a, b, size); - else - swap_func(a, b, (int)size, priv); -} - -#define _CMP_WRAPPER ((cmp_r_func_t)0L) - -static int do_cmp(const void *a, const void *b, cmp_r_func_t cmp, const void *priv) -{ - if (cmp == _CMP_WRAPPER) - return ((const struct wrapper *)priv)->cmp(a, b); - return cmp(a, b, priv); -} - -static inline int eytzinger1_do_cmp(void *base1, size_t n, size_t size, - cmp_r_func_t cmp_func, const void *priv, - size_t l, size_t r) -{ - return do_cmp(base1 + inorder_to_eytzinger1(l, n) * size, - base1 + inorder_to_eytzinger1(r, n) * size, - cmp_func, priv); -} - -static inline void eytzinger1_do_swap(void *base1, size_t n, size_t size, - swap_r_func_t swap_func, const void *priv, - size_t l, size_t r) -{ - do_swap(base1 + inorder_to_eytzinger1(l, n) * size, - base1 + inorder_to_eytzinger1(r, n) * size, - size, swap_func, priv); -} - -static void eytzinger1_sort_r(void *base1, size_t n, size_t size, - cmp_r_func_t cmp_func, - swap_r_func_t swap_func, - const void *priv) -{ - unsigned i, j, k; - - /* called from 'sort' without swap function, let's pick the default */ - if (swap_func == SWAP_WRAPPER && !((struct wrapper *)priv)->swap_func) - swap_func = NULL; - - if (!swap_func) { - if (is_aligned(base1, size, 8)) - swap_func = SWAP_WORDS_64; - else if (is_aligned(base1, size, 4)) - swap_func = SWAP_WORDS_32; - else - swap_func = SWAP_BYTES; - } - - /* heapify */ - for (i = n / 2; i >= 1; --i) { - /* Find the sift-down path all the way to the leaves. */ - for (j = i; k = j * 2, k < n;) - j = eytzinger1_do_cmp(base1, n, size, cmp_func, priv, k, k + 1) > 0 ? k : k + 1; - - /* Special case for the last leaf with no sibling. */ - if (j * 2 == n) - j *= 2; - - /* Backtrack to the correct location. */ - while (j != i && eytzinger1_do_cmp(base1, n, size, cmp_func, priv, i, j) >= 0) - j /= 2; - - /* Shift the element into its correct place. */ - for (k = j; j != i;) { - j /= 2; - eytzinger1_do_swap(base1, n, size, swap_func, priv, j, k); - } - } - - /* sort */ - for (i = n; i > 1; --i) { - eytzinger1_do_swap(base1, n, size, swap_func, priv, 1, i); - - /* Find the sift-down path all the way to the leaves. */ - for (j = 1; k = j * 2, k + 1 < i;) - j = eytzinger1_do_cmp(base1, n, size, cmp_func, priv, k, k + 1) > 0 ? k : k + 1; - - /* Special case for the last leaf with no sibling. */ - if (j * 2 + 1 == i) - j *= 2; - - /* Backtrack to the correct location. */ - while (j >= 1 && eytzinger1_do_cmp(base1, n, size, cmp_func, priv, 1, j) >= 0) - j /= 2; - - /* Shift the element into its correct place. */ - for (k = j; j > 1;) { - j /= 2; - eytzinger1_do_swap(base1, n, size, swap_func, priv, j, k); - } - } -} - -void eytzinger0_sort_r(void *base, size_t n, size_t size, - cmp_r_func_t cmp_func, - swap_r_func_t swap_func, - const void *priv) -{ - void *base1 = base - size; - - return eytzinger1_sort_r(base1, n, size, cmp_func, swap_func, priv); -} - -void eytzinger0_sort(void *base, size_t n, size_t size, - cmp_func_t cmp_func, - swap_func_t swap_func) -{ - struct wrapper w = { - .cmp = cmp_func, - .swap_func = swap_func, - }; - - 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 |