Linux kernel mirror (for testing)
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1/* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright 2002 H. Peter Anvin - All Rights Reserved
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
8 * Boston MA 02111-1307, USA; either version 2 of the License, or
9 * (at your option) any later version; incorporated herein by reference.
10 *
11 * ----------------------------------------------------------------------- */
12
13/*
14 * raid6/algos.c
15 *
16 * Algorithm list and algorithm selection for RAID-6
17 */
18
19#include <linux/raid/pq.h>
20#ifndef __KERNEL__
21#include <sys/mman.h>
22#include <stdio.h>
23#else
24#include <linux/module.h>
25#include <linux/gfp.h>
26#if !RAID6_USE_EMPTY_ZERO_PAGE
27/* In .bss so it's zeroed */
28const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
29EXPORT_SYMBOL(raid6_empty_zero_page);
30#endif
31#endif
32
33struct raid6_calls raid6_call;
34EXPORT_SYMBOL_GPL(raid6_call);
35
36const struct raid6_calls * const raid6_algos[] = {
37#if defined(__ia64__)
38 &raid6_intx16,
39 &raid6_intx32,
40#endif
41#if defined(__i386__) && !defined(__arch_um__)
42 &raid6_mmxx1,
43 &raid6_mmxx2,
44 &raid6_sse1x1,
45 &raid6_sse1x2,
46 &raid6_sse2x1,
47 &raid6_sse2x2,
48#ifdef CONFIG_AS_AVX2
49 &raid6_avx2x1,
50 &raid6_avx2x2,
51#endif
52#endif
53#if defined(__x86_64__) && !defined(__arch_um__)
54 &raid6_sse2x1,
55 &raid6_sse2x2,
56 &raid6_sse2x4,
57#ifdef CONFIG_AS_AVX2
58 &raid6_avx2x1,
59 &raid6_avx2x2,
60 &raid6_avx2x4,
61#endif
62#endif
63#ifdef CONFIG_ALTIVEC
64 &raid6_altivec1,
65 &raid6_altivec2,
66 &raid6_altivec4,
67 &raid6_altivec8,
68#endif
69 &raid6_intx1,
70 &raid6_intx2,
71 &raid6_intx4,
72 &raid6_intx8,
73 NULL
74};
75
76void (*raid6_2data_recov)(int, size_t, int, int, void **);
77EXPORT_SYMBOL_GPL(raid6_2data_recov);
78
79void (*raid6_datap_recov)(int, size_t, int, void **);
80EXPORT_SYMBOL_GPL(raid6_datap_recov);
81
82const struct raid6_recov_calls *const raid6_recov_algos[] = {
83#if (defined(__i386__) || defined(__x86_64__)) && !defined(__arch_um__)
84#ifdef CONFIG_AS_AVX2
85 &raid6_recov_avx2,
86#endif
87 &raid6_recov_ssse3,
88#endif
89 &raid6_recov_intx1,
90 NULL
91};
92
93#ifdef __KERNEL__
94#define RAID6_TIME_JIFFIES_LG2 4
95#else
96/* Need more time to be stable in userspace */
97#define RAID6_TIME_JIFFIES_LG2 9
98#define time_before(x, y) ((x) < (y))
99#endif
100
101static inline const struct raid6_recov_calls *raid6_choose_recov(void)
102{
103 const struct raid6_recov_calls *const *algo;
104 const struct raid6_recov_calls *best;
105
106 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
107 if (!best || (*algo)->priority > best->priority)
108 if (!(*algo)->valid || (*algo)->valid())
109 best = *algo;
110
111 if (best) {
112 raid6_2data_recov = best->data2;
113 raid6_datap_recov = best->datap;
114
115 printk("raid6: using %s recovery algorithm\n", best->name);
116 } else
117 printk("raid6: Yikes! No recovery algorithm found!\n");
118
119 return best;
120}
121
122static inline const struct raid6_calls *raid6_choose_gen(
123 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
124{
125 unsigned long perf, bestperf, j0, j1;
126 const struct raid6_calls *const *algo;
127 const struct raid6_calls *best;
128
129 for (bestperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
130 if (!best || (*algo)->prefer >= best->prefer) {
131 if ((*algo)->valid && !(*algo)->valid())
132 continue;
133
134 perf = 0;
135
136 preempt_disable();
137 j0 = jiffies;
138 while ((j1 = jiffies) == j0)
139 cpu_relax();
140 while (time_before(jiffies,
141 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
142 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
143 perf++;
144 }
145 preempt_enable();
146
147 if (perf > bestperf) {
148 bestperf = perf;
149 best = *algo;
150 }
151 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
152 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
153 }
154 }
155
156 if (best) {
157 printk("raid6: using algorithm %s (%ld MB/s)\n",
158 best->name,
159 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
160 raid6_call = *best;
161 } else
162 printk("raid6: Yikes! No algorithm found!\n");
163
164 return best;
165}
166
167
168/* Try to pick the best algorithm */
169/* This code uses the gfmul table as convenient data set to abuse */
170
171int __init raid6_select_algo(void)
172{
173 const int disks = (65536/PAGE_SIZE)+2;
174
175 const struct raid6_calls *gen_best;
176 const struct raid6_recov_calls *rec_best;
177 char *syndromes;
178 void *dptrs[(65536/PAGE_SIZE)+2];
179 int i;
180
181 for (i = 0; i < disks-2; i++)
182 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
183
184 /* Normal code - use a 2-page allocation to avoid D$ conflict */
185 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
186
187 if (!syndromes) {
188 printk("raid6: Yikes! No memory available.\n");
189 return -ENOMEM;
190 }
191
192 dptrs[disks-2] = syndromes;
193 dptrs[disks-1] = syndromes + PAGE_SIZE;
194
195 /* select raid gen_syndrome function */
196 gen_best = raid6_choose_gen(&dptrs, disks);
197
198 /* select raid recover functions */
199 rec_best = raid6_choose_recov();
200
201 free_pages((unsigned long)syndromes, 1);
202
203 return gen_best && rec_best ? 0 : -EINVAL;
204}
205
206static void raid6_exit(void)
207{
208 do { } while (0);
209}
210
211subsys_initcall(raid6_select_algo);
212module_exit(raid6_exit);
213MODULE_LICENSE("GPL");
214MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");