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#endif
49#if defined(__x86_64__) && !defined(__arch_um__)
50 &raid6_sse2x1,
51 &raid6_sse2x2,
52 &raid6_sse2x4,
53#endif
54#ifdef CONFIG_ALTIVEC
55 &raid6_altivec1,
56 &raid6_altivec2,
57 &raid6_altivec4,
58 &raid6_altivec8,
59#endif
60 &raid6_intx1,
61 &raid6_intx2,
62 &raid6_intx4,
63 &raid6_intx8,
64 NULL
65};
66
67void (*raid6_2data_recov)(int, size_t, int, int, void **);
68EXPORT_SYMBOL_GPL(raid6_2data_recov);
69
70void (*raid6_datap_recov)(int, size_t, int, void **);
71EXPORT_SYMBOL_GPL(raid6_datap_recov);
72
73const struct raid6_recov_calls *const raid6_recov_algos[] = {
74#if (defined(__i386__) || defined(__x86_64__)) && !defined(__arch_um__)
75 &raid6_recov_ssse3,
76#endif
77 &raid6_recov_intx1,
78 NULL
79};
80
81#ifdef __KERNEL__
82#define RAID6_TIME_JIFFIES_LG2 4
83#else
84/* Need more time to be stable in userspace */
85#define RAID6_TIME_JIFFIES_LG2 9
86#define time_before(x, y) ((x) < (y))
87#endif
88
89static inline const struct raid6_recov_calls *raid6_choose_recov(void)
90{
91 const struct raid6_recov_calls *const *algo;
92 const struct raid6_recov_calls *best;
93
94 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
95 if (!best || (*algo)->priority > best->priority)
96 if (!(*algo)->valid || (*algo)->valid())
97 best = *algo;
98
99 if (best) {
100 raid6_2data_recov = best->data2;
101 raid6_datap_recov = best->datap;
102
103 printk("raid6: using %s recovery algorithm\n", best->name);
104 } else
105 printk("raid6: Yikes! No recovery algorithm found!\n");
106
107 return best;
108}
109
110static inline const struct raid6_calls *raid6_choose_gen(
111 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
112{
113 unsigned long perf, bestperf, j0, j1;
114 const struct raid6_calls *const *algo;
115 const struct raid6_calls *best;
116
117 for (bestperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
118 if (!best || (*algo)->prefer >= best->prefer) {
119 if ((*algo)->valid && !(*algo)->valid())
120 continue;
121
122 perf = 0;
123
124 preempt_disable();
125 j0 = jiffies;
126 while ((j1 = jiffies) == j0)
127 cpu_relax();
128 while (time_before(jiffies,
129 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
130 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
131 perf++;
132 }
133 preempt_enable();
134
135 if (perf > bestperf) {
136 bestperf = perf;
137 best = *algo;
138 }
139 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
140 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
141 }
142 }
143
144 if (best) {
145 printk("raid6: using algorithm %s (%ld MB/s)\n",
146 best->name,
147 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
148 raid6_call = *best;
149 } else
150 printk("raid6: Yikes! No algorithm found!\n");
151
152 return best;
153}
154
155
156/* Try to pick the best algorithm */
157/* This code uses the gfmul table as convenient data set to abuse */
158
159int __init raid6_select_algo(void)
160{
161 const int disks = (65536/PAGE_SIZE)+2;
162
163 const struct raid6_calls *gen_best;
164 const struct raid6_recov_calls *rec_best;
165 char *syndromes;
166 void *dptrs[(65536/PAGE_SIZE)+2];
167 int i;
168
169 for (i = 0; i < disks-2; i++)
170 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
171
172 /* Normal code - use a 2-page allocation to avoid D$ conflict */
173 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
174
175 if (!syndromes) {
176 printk("raid6: Yikes! No memory available.\n");
177 return -ENOMEM;
178 }
179
180 dptrs[disks-2] = syndromes;
181 dptrs[disks-1] = syndromes + PAGE_SIZE;
182
183 /* select raid gen_syndrome function */
184 gen_best = raid6_choose_gen(&dptrs, disks);
185
186 /* select raid recover functions */
187 rec_best = raid6_choose_recov();
188
189 free_pages((unsigned long)syndromes, 1);
190
191 return gen_best && rec_best ? 0 : -EINVAL;
192}
193
194static void raid6_exit(void)
195{
196 do { } while (0);
197}
198
199subsys_initcall(raid6_select_algo);
200module_exit(raid6_exit);
201MODULE_LICENSE("GPL");
202MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");