1 /* -*- linux-c -*- ------------------------------------------------------- *
3 * Copyright 2002 H. Peter Anvin - All Rights Reserved
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.
11 * ----------------------------------------------------------------------- */
16 * Algorithm list and algorithm selection for RAID-6
19 #include <linux/raid/pq.h>
24 #include <linux/module.h>
25 #include <linux/gfp.h>
26 #if !RAID6_USE_EMPTY_ZERO_PAGE
27 /* In .bss so it's zeroed */
28 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
29 EXPORT_SYMBOL(raid6_empty_zero_page);
33 struct raid6_calls raid6_call;
34 EXPORT_SYMBOL_GPL(raid6_call);
36 const struct raid6_calls * const raid6_algos[] = {
41 #if defined(__i386__) && !defined(__arch_um__)
53 #if defined(__x86_64__) && !defined(__arch_um__)
73 #ifdef CONFIG_KERNEL_MODE_NEON
82 void (*raid6_2data_recov)(int, size_t, int, int, void **);
83 EXPORT_SYMBOL_GPL(raid6_2data_recov);
85 void (*raid6_datap_recov)(int, size_t, int, void **);
86 EXPORT_SYMBOL_GPL(raid6_datap_recov);
88 const struct raid6_recov_calls *const raid6_recov_algos[] = {
89 #if (defined(__i386__) || defined(__x86_64__)) && !defined(__arch_um__)
100 #define RAID6_TIME_JIFFIES_LG2 4
102 /* Need more time to be stable in userspace */
103 #define RAID6_TIME_JIFFIES_LG2 9
104 #define time_before(x, y) ((x) < (y))
107 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
109 const struct raid6_recov_calls *const *algo;
110 const struct raid6_recov_calls *best;
112 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
113 if (!best || (*algo)->priority > best->priority)
114 if (!(*algo)->valid || (*algo)->valid())
118 raid6_2data_recov = best->data2;
119 raid6_datap_recov = best->datap;
121 printk("raid6: using %s recovery algorithm\n", best->name);
123 printk("raid6: Yikes! No recovery algorithm found!\n");
128 static inline const struct raid6_calls *raid6_choose_gen(
129 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
131 unsigned long perf, bestperf, j0, j1;
132 const struct raid6_calls *const *algo;
133 const struct raid6_calls *best;
135 for (bestperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
136 if (!best || (*algo)->prefer >= best->prefer) {
137 if ((*algo)->valid && !(*algo)->valid())
144 while ((j1 = jiffies) == j0)
146 while (time_before(jiffies,
147 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
148 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
153 if (perf > bestperf) {
157 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
158 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
163 printk("raid6: using algorithm %s (%ld MB/s)\n",
165 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
168 printk("raid6: Yikes! No algorithm found!\n");
174 /* Try to pick the best algorithm */
175 /* This code uses the gfmul table as convenient data set to abuse */
177 int __init raid6_select_algo(void)
179 const int disks = (65536/PAGE_SIZE)+2;
181 const struct raid6_calls *gen_best;
182 const struct raid6_recov_calls *rec_best;
184 void *dptrs[(65536/PAGE_SIZE)+2];
187 for (i = 0; i < disks-2; i++)
188 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
190 /* Normal code - use a 2-page allocation to avoid D$ conflict */
191 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
194 printk("raid6: Yikes! No memory available.\n");
198 dptrs[disks-2] = syndromes;
199 dptrs[disks-1] = syndromes + PAGE_SIZE;
201 /* select raid gen_syndrome function */
202 gen_best = raid6_choose_gen(&dptrs, disks);
204 /* select raid recover functions */
205 rec_best = raid6_choose_recov();
207 free_pages((unsigned long)syndromes, 1);
209 return gen_best && rec_best ? 0 : -EINVAL;
212 static void raid6_exit(void)
217 subsys_initcall(raid6_select_algo);
218 module_exit(raid6_exit);
219 MODULE_LICENSE("GPL");
220 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");