1 /* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright 2002 H. Peter Anvin - All Rights Reserved
4 *
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.
10 *
11 * ----------------------------------------------------------------------- */
12
13 /*
14 * raid6/algos.c
15 *
16 * Algorithm list and algorithm selection for RAID-6
17 */
18
19 #include <linux/raid/pq.h>
20 #ifndef __KERNEL__
21 #include <sys/mman.h>
22 #include <stdio.h>
23 #else
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);
30 #endif
31 #endif
32
33 struct raid6_calls raid6_call;
34 EXPORT_SYMBOL_GPL(raid6_call);
35
36 const struct raid6_calls * const raid6_algos[] = {
37 #if defined(__ia64__)
38 &raid6_intx16,
39 &raid6_intx32,
40 #endif
41 #if defined(__i386__) && !defined(__arch_um__)
42 &raid6_mmxx1,
43 &raid6_mmxx2,
44 &raid6_sse1x1,
45 &raid6_sse1x2,
46 &raid6_sse2x1,
47 &raid6_sse2x2,
48 #ifdef CONFIG_AS_AVX2
49 &raid6_avx2x1,
50 &raid6_avx2x2,
51 #endif
52 #ifdef CONFIG_AS_AVX512
53 &raid6_avx512x1,
54 &raid6_avx512x2,
55 #endif
56 #endif
57 #if defined(__x86_64__) && !defined(__arch_um__)
58 &raid6_sse2x1,
59 &raid6_sse2x2,
60 &raid6_sse2x4,
61 #ifdef CONFIG_AS_AVX2
62 &raid6_avx2x1,
63 &raid6_avx2x2,
64 &raid6_avx2x4,
65 #endif
66 #ifdef CONFIG_AS_AVX512
67 &raid6_avx512x1,
68 &raid6_avx512x2,
69 &raid6_avx512x4,
70 #endif
71 #endif
72 #ifdef CONFIG_ALTIVEC
73 &raid6_altivec1,
74 &raid6_altivec2,
75 &raid6_altivec4,
76 &raid6_altivec8,
77 &raid6_vpermxor1,
78 &raid6_vpermxor2,
79 &raid6_vpermxor4,
80 &raid6_vpermxor8,
81 #endif
82 #if defined(CONFIG_S390)
83 &raid6_s390vx8,
84 #endif
85 &raid6_intx1,
86 &raid6_intx2,
87 &raid6_intx4,
88 &raid6_intx8,
89 #ifdef CONFIG_KERNEL_MODE_NEON
90 &raid6_neonx1,
91 &raid6_neonx2,
92 &raid6_neonx4,
93 &raid6_neonx8,
94 #endif
95 NULL
96 };
97
98 void (*raid6_2data_recov)(int, size_t, int, int, void **);
99 EXPORT_SYMBOL_GPL(raid6_2data_recov);
100
101 void (*raid6_datap_recov)(int, size_t, int, void **);
102 EXPORT_SYMBOL_GPL(raid6_datap_recov);
103
104 const struct raid6_recov_calls *const raid6_recov_algos[] = {
105 #ifdef CONFIG_AS_AVX512
106 &raid6_recov_avx512,
107 #endif
108 #ifdef CONFIG_AS_AVX2
109 &raid6_recov_avx2,
110 #endif
111 #ifdef CONFIG_AS_SSSE3
112 &raid6_recov_ssse3,
113 #endif
114 #ifdef CONFIG_S390
115 &raid6_recov_s390xc,
116 #endif
117 #if defined(CONFIG_KERNEL_MODE_NEON)
118 &raid6_recov_neon,
119 #endif
120 &raid6_recov_intx1,
121 NULL
122 };
123
124 #ifdef __KERNEL__
125 #define RAID6_TIME_JIFFIES_LG2 4
126 #else
127 /* Need more time to be stable in userspace */
128 #define RAID6_TIME_JIFFIES_LG2 9
129 #define time_before(x, y) ((x) < (y))
130 #endif
131
raid6_choose_recov(void)132 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
133 {
134 const struct raid6_recov_calls *const *algo;
135 const struct raid6_recov_calls *best;
136
137 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
138 if (!best || (*algo)->priority > best->priority)
139 if (!(*algo)->valid || (*algo)->valid())
140 best = *algo;
141
142 if (best) {
143 raid6_2data_recov = best->data2;
144 raid6_datap_recov = best->datap;
145
146 pr_info("raid6: using %s recovery algorithm\n", best->name);
147 } else
148 pr_err("raid6: Yikes! No recovery algorithm found!\n");
149
150 return best;
151 }
152
raid6_choose_gen(void * (* const dptrs)[(65536/PAGE_SIZE)+2],const int disks)153 static inline const struct raid6_calls *raid6_choose_gen(
154 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
155 {
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;
160
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())
164 continue;
165
166 perf = 0;
167
168 preempt_disable();
169 j0 = jiffies;
170 while ((j1 = jiffies) == j0)
171 cpu_relax();
172 while (time_before(jiffies,
173 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
174 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
175 perf++;
176 }
177 preempt_enable();
178
179 if (perf > bestgenperf) {
180 bestgenperf = perf;
181 best = *algo;
182 }
183 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
184 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
185
186 if (!(*algo)->xor_syndrome)
187 continue;
188
189 perf = 0;
190
191 preempt_disable();
192 j0 = jiffies;
193 while ((j1 = jiffies) == j0)
194 cpu_relax();
195 while (time_before(jiffies,
196 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
197 (*algo)->xor_syndrome(disks, start, stop,
198 PAGE_SIZE, *dptrs);
199 perf++;
200 }
201 preempt_enable();
202
203 if (best == *algo)
204 bestxorperf = perf;
205
206 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
207 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
208 }
209 }
210
211 if (best) {
212 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
213 best->name,
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));
218 raid6_call = *best;
219 } else
220 pr_err("raid6: Yikes! No algorithm found!\n");
221
222 return best;
223 }
224
225
226 /* Try to pick the best algorithm */
227 /* This code uses the gfmul table as convenient data set to abuse */
228
raid6_select_algo(void)229 int __init raid6_select_algo(void)
230 {
231 const int disks = (65536/PAGE_SIZE)+2;
232
233 const struct raid6_calls *gen_best;
234 const struct raid6_recov_calls *rec_best;
235 char *syndromes;
236 void *dptrs[(65536/PAGE_SIZE)+2];
237 int i;
238
239 for (i = 0; i < disks-2; i++)
240 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
241
242 /* Normal code - use a 2-page allocation to avoid D$ conflict */
243 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
244
245 if (!syndromes) {
246 pr_err("raid6: Yikes! No memory available.\n");
247 return -ENOMEM;
248 }
249
250 dptrs[disks-2] = syndromes;
251 dptrs[disks-1] = syndromes + PAGE_SIZE;
252
253 /* select raid gen_syndrome function */
254 gen_best = raid6_choose_gen(&dptrs, disks);
255
256 /* select raid recover functions */
257 rec_best = raid6_choose_recov();
258
259 free_pages((unsigned long)syndromes, 1);
260
261 return gen_best && rec_best ? 0 : -EINVAL;
262 }
263
raid6_exit(void)264 static void raid6_exit(void)
265 {
266 do { } while (0);
267 }
268
269 subsys_initcall(raid6_select_algo);
270 module_exit(raid6_exit);
271 MODULE_LICENSE("GPL");
272 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
273