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[] = {
37 #if defined(__i386__) && !defined(__arch_um__)
38 #ifdef CONFIG_AS_AVX512
53 #if defined(__x86_64__) && !defined(__arch_um__)
54 #ifdef CONFIG_AS_AVX512
78 #if defined(CONFIG_S390)
81 #ifdef CONFIG_KERNEL_MODE_NEON
98 void (*raid6_2data_recov)(int, size_t, int, int, void **);
99 EXPORT_SYMBOL_GPL(raid6_2data_recov);
101 void (*raid6_datap_recov)(int, size_t, int, void **);
102 EXPORT_SYMBOL_GPL(raid6_datap_recov);
104 const struct raid6_recov_calls *const raid6_recov_algos[] = {
105 #ifdef CONFIG_AS_AVX512
108 #ifdef CONFIG_AS_AVX2
111 #ifdef CONFIG_AS_SSSE3
117 #if defined(CONFIG_KERNEL_MODE_NEON)
125 #define RAID6_TIME_JIFFIES_LG2 4
127 /* Need more time to be stable in userspace */
128 #define RAID6_TIME_JIFFIES_LG2 9
129 #define time_before(x, y) ((x) < (y))
132 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
134 const struct raid6_recov_calls *const *algo;
135 const struct raid6_recov_calls *best;
137 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
138 if (!best || (*algo)->priority > best->priority)
139 if (!(*algo)->valid || (*algo)->valid())
143 raid6_2data_recov = best->data2;
144 raid6_datap_recov = best->datap;
146 pr_info("raid6: using %s recovery algorithm\n", best->name);
148 pr_err("raid6: Yikes! No recovery algorithm found!\n");
153 static inline const struct raid6_calls *raid6_choose_gen(
154 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
156 unsigned long perf, bestgenperf, bestxorperf, j0, j1;
157 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
158 const struct raid6_calls *const *algo;
159 const struct raid6_calls *best;
161 for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
162 if (!best || (*algo)->prefer >= best->prefer) {
163 if ((*algo)->valid && !(*algo)->valid())
166 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
175 while ((j1 = jiffies) == j0)
177 while (time_before(jiffies,
178 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
179 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
184 if (perf > bestgenperf) {
188 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
189 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
191 if (!(*algo)->xor_syndrome)
198 while ((j1 = jiffies) == j0)
200 while (time_before(jiffies,
201 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
202 (*algo)->xor_syndrome(disks, start, stop,
211 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
212 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
217 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
219 (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
220 if (best->xor_syndrome)
221 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
222 (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
225 pr_err("raid6: Yikes! No algorithm found!\n");
231 /* Try to pick the best algorithm */
232 /* This code uses the gfmul table as convenient data set to abuse */
234 int __init raid6_select_algo(void)
236 const int disks = (65536/PAGE_SIZE)+2;
238 const struct raid6_calls *gen_best;
239 const struct raid6_recov_calls *rec_best;
241 void *dptrs[(65536/PAGE_SIZE)+2];
244 for (i = 0; i < disks-2; i++)
245 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
247 /* Normal code - use a 2-page allocation to avoid D$ conflict */
248 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
251 pr_err("raid6: Yikes! No memory available.\n");
255 dptrs[disks-2] = syndromes;
256 dptrs[disks-1] = syndromes + PAGE_SIZE;
258 /* select raid gen_syndrome function */
259 gen_best = raid6_choose_gen(&dptrs, disks);
261 /* select raid recover functions */
262 rec_best = raid6_choose_recov();
264 free_pages((unsigned long)syndromes, 1);
266 return gen_best && rec_best ? 0 : -EINVAL;
269 static void raid6_exit(void)
274 subsys_initcall(raid6_select_algo);
275 module_exit(raid6_exit);
276 MODULE_LICENSE("GPL");
277 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");