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
48 #if defined(__x86_64__) && !defined(__arch_um__)
49 #ifdef CONFIG_AS_AVX512
73 #if defined(CONFIG_S390)
76 #ifdef CONFIG_KERNEL_MODE_NEON
93 void (*raid6_2data_recov)(int, size_t, int, int, void **);
94 EXPORT_SYMBOL_GPL(raid6_2data_recov);
96 void (*raid6_datap_recov)(int, size_t, int, void **);
97 EXPORT_SYMBOL_GPL(raid6_datap_recov);
99 const struct raid6_recov_calls *const raid6_recov_algos[] = {
100 #ifdef CONFIG_AS_AVX512
103 #ifdef CONFIG_AS_AVX2
106 #ifdef CONFIG_AS_SSSE3
112 #if defined(CONFIG_KERNEL_MODE_NEON)
120 #define RAID6_TIME_JIFFIES_LG2 4
122 /* Need more time to be stable in userspace */
123 #define RAID6_TIME_JIFFIES_LG2 9
124 #define time_before(x, y) ((x) < (y))
127 #define RAID6_TEST_DISKS 8
128 #define RAID6_TEST_DISKS_ORDER 3
130 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
132 const struct raid6_recov_calls *const *algo;
133 const struct raid6_recov_calls *best;
135 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
136 if (!best || (*algo)->priority > best->priority)
137 if (!(*algo)->valid || (*algo)->valid())
141 raid6_2data_recov = best->data2;
142 raid6_datap_recov = best->datap;
144 pr_info("raid6: using %s recovery algorithm\n", best->name);
146 pr_err("raid6: Yikes! No recovery algorithm found!\n");
151 static inline const struct raid6_calls *raid6_choose_gen(
152 void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
154 unsigned long perf, bestgenperf, bestxorperf, j0, j1;
155 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
156 const struct raid6_calls *const *algo;
157 const struct raid6_calls *best;
159 for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
160 if (!best || (*algo)->prefer >= best->prefer) {
161 if ((*algo)->valid && !(*algo)->valid())
164 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
173 while ((j1 = jiffies) == j0)
175 while (time_before(jiffies,
176 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
177 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
182 if (perf > bestgenperf) {
186 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
187 (perf * HZ * (disks-2)) >>
188 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
190 if (!(*algo)->xor_syndrome)
197 while ((j1 = jiffies) == j0)
199 while (time_before(jiffies,
200 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
201 (*algo)->xor_syndrome(disks, start, stop,
210 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
211 (perf * HZ * (disks-2)) >>
212 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
217 if (IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
218 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
220 (bestgenperf * HZ * (disks-2)) >>
221 (20 - PAGE_SHIFT+RAID6_TIME_JIFFIES_LG2));
222 if (best->xor_syndrome)
223 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
224 (bestxorperf * HZ * (disks-2)) >>
225 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
227 pr_info("raid6: skip pq benchmark and using algorithm %s\n",
231 pr_err("raid6: Yikes! No algorithm found!\n");
237 /* Try to pick the best algorithm */
238 /* This code uses the gfmul table as convenient data set to abuse */
240 int __init raid6_select_algo(void)
242 const int disks = RAID6_TEST_DISKS;
244 const struct raid6_calls *gen_best;
245 const struct raid6_recov_calls *rec_best;
247 void *dptrs[RAID6_TEST_DISKS];
250 /* prepare the buffer and fill it circularly with gfmul table */
251 disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
253 pr_err("raid6: Yikes! No memory available.\n");
258 for (i = 0; i < disks; i++)
259 dptrs[i] = p + PAGE_SIZE * i;
261 cycle = ((disks - 2) * PAGE_SIZE) / 65536;
262 for (i = 0; i < cycle; i++) {
263 memcpy(p, raid6_gfmul, 65536);
267 if ((disks - 2) * PAGE_SIZE % 65536)
268 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
270 /* select raid gen_syndrome function */
271 gen_best = raid6_choose_gen(&dptrs, disks);
273 /* select raid recover functions */
274 rec_best = raid6_choose_recov();
276 free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
278 return gen_best && rec_best ? 0 : -EINVAL;
281 static void raid6_exit(void)
286 subsys_initcall(raid6_select_algo);
287 module_exit(raid6_exit);
288 MODULE_LICENSE("GPL");
289 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");