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__)
69 #if defined(CONFIG_TILEGX)
72 #if defined(CONFIG_S390)
79 #ifdef CONFIG_KERNEL_MODE_NEON
88 void (*raid6_2data_recov)(int, size_t, int, int, void **);
89 EXPORT_SYMBOL_GPL(raid6_2data_recov);
91 void (*raid6_datap_recov)(int, size_t, int, void **);
92 EXPORT_SYMBOL_GPL(raid6_datap_recov);
94 const struct raid6_recov_calls *const raid6_recov_algos[] = {
98 #ifdef CONFIG_AS_SSSE3
106 #define RAID6_TIME_JIFFIES_LG2 4
108 /* Need more time to be stable in userspace */
109 #define RAID6_TIME_JIFFIES_LG2 9
110 #define time_before(x, y) ((x) < (y))
113 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
115 const struct raid6_recov_calls *const *algo;
116 const struct raid6_recov_calls *best;
118 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
119 if (!best || (*algo)->priority > best->priority)
120 if (!(*algo)->valid || (*algo)->valid())
124 raid6_2data_recov = best->data2;
125 raid6_datap_recov = best->datap;
127 pr_info("raid6: using %s recovery algorithm\n", best->name);
129 pr_err("raid6: Yikes! No recovery algorithm found!\n");
134 static inline const struct raid6_calls *raid6_choose_gen(
135 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
137 unsigned long perf, bestgenperf, bestxorperf, j0, j1;
138 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
139 const struct raid6_calls *const *algo;
140 const struct raid6_calls *best;
142 for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
143 if (!best || (*algo)->prefer >= best->prefer) {
144 if ((*algo)->valid && !(*algo)->valid())
151 while ((j1 = jiffies) == j0)
153 while (time_before(jiffies,
154 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
155 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
160 if (perf > bestgenperf) {
164 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
165 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
167 if (!(*algo)->xor_syndrome)
174 while ((j1 = jiffies) == j0)
176 while (time_before(jiffies,
177 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
178 (*algo)->xor_syndrome(disks, start, stop,
187 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
188 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
193 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
195 (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
196 if (best->xor_syndrome)
197 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
198 (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
201 pr_err("raid6: Yikes! No algorithm found!\n");
207 /* Try to pick the best algorithm */
208 /* This code uses the gfmul table as convenient data set to abuse */
210 int __init raid6_select_algo(void)
212 const int disks = (65536/PAGE_SIZE)+2;
214 const struct raid6_calls *gen_best;
215 const struct raid6_recov_calls *rec_best;
217 void *dptrs[(65536/PAGE_SIZE)+2];
220 for (i = 0; i < disks-2; i++)
221 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
223 /* Normal code - use a 2-page allocation to avoid D$ conflict */
224 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
227 pr_err("raid6: Yikes! No memory available.\n");
231 dptrs[disks-2] = syndromes;
232 dptrs[disks-1] = syndromes + PAGE_SIZE;
234 /* select raid gen_syndrome function */
235 gen_best = raid6_choose_gen(&dptrs, disks);
237 /* select raid recover functions */
238 rec_best = raid6_choose_recov();
240 free_pages((unsigned long)syndromes, 1);
242 return gen_best && rec_best ? 0 : -EINVAL;
245 static void raid6_exit(void)
250 subsys_initcall(raid6_select_algo);
251 module_exit(raid6_exit);
252 MODULE_LICENSE("GPL");
253 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");