1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* -*- linux-c -*- ------------------------------------------------------- *
4 * Copyright 2002 H. Peter Anvin - All Rights Reserved
6 * ----------------------------------------------------------------------- */
11 * Algorithm list and algorithm selection for RAID-6
14 #include <linux/raid/pq.h>
19 #include <linux/module.h>
20 #include <linux/gfp.h>
21 #if !RAID6_USE_EMPTY_ZERO_PAGE
22 /* In .bss so it's zeroed */
23 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
24 EXPORT_SYMBOL(raid6_empty_zero_page);
28 struct raid6_calls raid6_call;
29 EXPORT_SYMBOL_GPL(raid6_call);
31 const struct raid6_calls * const raid6_algos[] = {
32 #if defined(__i386__) && !defined(__arch_um__)
33 #ifdef CONFIG_AS_AVX512
46 #if defined(__x86_64__) && !defined(__arch_um__)
47 #ifdef CONFIG_AS_AVX512
69 #if defined(CONFIG_S390)
72 #ifdef CONFIG_KERNEL_MODE_NEON
89 void (*raid6_2data_recov)(int, size_t, int, int, void **);
90 EXPORT_SYMBOL_GPL(raid6_2data_recov);
92 void (*raid6_datap_recov)(int, size_t, int, void **);
93 EXPORT_SYMBOL_GPL(raid6_datap_recov);
95 const struct raid6_recov_calls *const raid6_recov_algos[] = {
97 #ifdef CONFIG_AS_AVX512
106 #if defined(CONFIG_KERNEL_MODE_NEON)
114 #define RAID6_TIME_JIFFIES_LG2 4
116 /* Need more time to be stable in userspace */
117 #define RAID6_TIME_JIFFIES_LG2 9
118 #define time_before(x, y) ((x) < (y))
121 #define RAID6_TEST_DISKS 8
122 #define RAID6_TEST_DISKS_ORDER 3
124 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
126 const struct raid6_recov_calls *const *algo;
127 const struct raid6_recov_calls *best;
129 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
130 if (!best || (*algo)->priority > best->priority)
131 if (!(*algo)->valid || (*algo)->valid())
135 raid6_2data_recov = best->data2;
136 raid6_datap_recov = best->datap;
138 pr_info("raid6: using %s recovery algorithm\n", best->name);
140 pr_err("raid6: Yikes! No recovery algorithm found!\n");
145 static inline const struct raid6_calls *raid6_choose_gen(
146 void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
148 unsigned long perf, bestgenperf, j0, j1;
149 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
150 const struct raid6_calls *const *algo;
151 const struct raid6_calls *best;
153 for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
154 if (!best || (*algo)->priority >= best->priority) {
155 if ((*algo)->valid && !(*algo)->valid())
158 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
167 while ((j1 = jiffies) == j0)
169 while (time_before(jiffies,
170 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
171 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
176 if (perf > bestgenperf) {
180 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
181 (perf * HZ * (disks-2)) >>
182 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
187 pr_err("raid6: Yikes! No algorithm found!\n");
193 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
194 pr_info("raid6: skipped pq benchmark and selected %s\n",
199 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
201 (bestgenperf * HZ * (disks - 2)) >>
202 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
204 if (best->xor_syndrome) {
209 while ((j1 = jiffies) == j0)
211 while (time_before(jiffies,
212 j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
213 best->xor_syndrome(disks, start, stop,
219 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
220 (perf * HZ * (disks - 2)) >>
221 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
229 /* Try to pick the best algorithm */
230 /* This code uses the gfmul table as convenient data set to abuse */
232 int __init raid6_select_algo(void)
234 const int disks = RAID6_TEST_DISKS;
236 const struct raid6_calls *gen_best;
237 const struct raid6_recov_calls *rec_best;
239 void *dptrs[RAID6_TEST_DISKS];
242 /* prepare the buffer and fill it circularly with gfmul table */
243 disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
245 pr_err("raid6: Yikes! No memory available.\n");
250 for (i = 0; i < disks; i++)
251 dptrs[i] = p + PAGE_SIZE * i;
253 cycle = ((disks - 2) * PAGE_SIZE) / 65536;
254 for (i = 0; i < cycle; i++) {
255 memcpy(p, raid6_gfmul, 65536);
259 if ((disks - 2) * PAGE_SIZE % 65536)
260 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
262 /* select raid gen_syndrome function */
263 gen_best = raid6_choose_gen(&dptrs, disks);
265 /* select raid recover functions */
266 rec_best = raid6_choose_recov();
268 free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
270 return gen_best && rec_best ? 0 : -EINVAL;
273 static void raid6_exit(void)
278 subsys_initcall(raid6_select_algo);
279 module_exit(raid6_exit);
280 MODULE_LICENSE("GPL");
281 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");