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 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
129 const struct raid6_recov_calls *const *algo;
130 const struct raid6_recov_calls *best;
132 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
133 if (!best || (*algo)->priority > best->priority)
134 if (!(*algo)->valid || (*algo)->valid())
138 raid6_2data_recov = best->data2;
139 raid6_datap_recov = best->datap;
141 pr_info("raid6: using %s recovery algorithm\n", best->name);
143 pr_err("raid6: Yikes! No recovery algorithm found!\n");
148 static inline const struct raid6_calls *raid6_choose_gen(
149 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
151 unsigned long perf, bestgenperf, bestxorperf, j0, j1;
152 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
153 const struct raid6_calls *const *algo;
154 const struct raid6_calls *best;
156 for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
157 if (!best || (*algo)->prefer >= best->prefer) {
158 if ((*algo)->valid && !(*algo)->valid())
161 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
170 while ((j1 = jiffies) == j0)
172 while (time_before(jiffies,
173 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
174 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
179 if (perf > bestgenperf) {
183 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
184 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
186 if (!(*algo)->xor_syndrome)
193 while ((j1 = jiffies) == j0)
195 while (time_before(jiffies,
196 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
197 (*algo)->xor_syndrome(disks, start, stop,
206 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
207 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
212 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
214 (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
215 if (best->xor_syndrome)
216 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
217 (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
220 pr_err("raid6: Yikes! No algorithm found!\n");
226 /* Try to pick the best algorithm */
227 /* This code uses the gfmul table as convenient data set to abuse */
229 int __init raid6_select_algo(void)
231 const int disks = (65536/PAGE_SIZE)+2;
233 const struct raid6_calls *gen_best;
234 const struct raid6_recov_calls *rec_best;
236 void *dptrs[(65536/PAGE_SIZE)+2];
239 for (i = 0; i < disks-2; i++)
240 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
242 /* Normal code - use a 2-page allocation to avoid D$ conflict */
243 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
246 pr_err("raid6: Yikes! No memory available.\n");
250 dptrs[disks-2] = syndromes;
251 dptrs[disks-1] = syndromes + PAGE_SIZE;
253 /* select raid gen_syndrome function */
254 gen_best = raid6_choose_gen(&dptrs, disks);
256 /* select raid recover functions */
257 rec_best = raid6_choose_recov();
259 free_pages((unsigned long)syndromes, 1);
261 return gen_best && rec_best ? 0 : -EINVAL;
264 static void raid6_exit(void)
269 subsys_initcall(raid6_select_algo);
270 module_exit(raid6_exit);
271 MODULE_LICENSE("GPL");
272 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");