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 #endif
53 #if defined(__x86_64__) && !defined(__arch_um__)
54 &raid6_sse2x1,
55 &raid6_sse2x2,
56 &raid6_sse2x4,
57 #ifdef CONFIG_AS_AVX2
58 &raid6_avx2x1,
59 &raid6_avx2x2,
60 &raid6_avx2x4,
61 #endif
62 #endif
63 #ifdef CONFIG_ALTIVEC
64 &raid6_altivec1,
65 &raid6_altivec2,
66 &raid6_altivec4,
67 &raid6_altivec8,
68 #endif
69 #if defined(CONFIG_TILEGX)
70 &raid6_tilegx8,
71 #endif
72 &raid6_intx1,
73 &raid6_intx2,
74 &raid6_intx4,
75 &raid6_intx8,
76 #ifdef CONFIG_KERNEL_MODE_NEON
77 &raid6_neonx1,
78 &raid6_neonx2,
79 &raid6_neonx4,
80 &raid6_neonx8,
81 #endif
82 NULL
83 };
84
85 void (*raid6_2data_recov)(int, size_t, int, int, void **);
86 EXPORT_SYMBOL_GPL(raid6_2data_recov);
87
88 void (*raid6_datap_recov)(int, size_t, int, void **);
89 EXPORT_SYMBOL_GPL(raid6_datap_recov);
90
91 const struct raid6_recov_calls *const raid6_recov_algos[] = {
92 #ifdef CONFIG_AS_AVX2
93 &raid6_recov_avx2,
94 #endif
95 #ifdef CONFIG_AS_SSSE3
96 &raid6_recov_ssse3,
97 #endif
98 &raid6_recov_intx1,
99 NULL
100 };
101
102 #ifdef __KERNEL__
103 #define RAID6_TIME_JIFFIES_LG2 4
104 #else
105 /* Need more time to be stable in userspace */
106 #define RAID6_TIME_JIFFIES_LG2 9
107 #define time_before(x, y) ((x) < (y))
108 #endif
109
raid6_choose_recov(void)110 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
111 {
112 const struct raid6_recov_calls *const *algo;
113 const struct raid6_recov_calls *best;
114
115 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
116 if (!best || (*algo)->priority > best->priority)
117 if (!(*algo)->valid || (*algo)->valid())
118 best = *algo;
119
120 if (best) {
121 raid6_2data_recov = best->data2;
122 raid6_datap_recov = best->datap;
123
124 pr_info("raid6: using %s recovery algorithm\n", best->name);
125 } else
126 pr_err("raid6: Yikes! No recovery algorithm found!\n");
127
128 return best;
129 }
130
raid6_choose_gen(void * (* const dptrs)[(65536/PAGE_SIZE)+2],const int disks)131 static inline const struct raid6_calls *raid6_choose_gen(
132 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
133 {
134 unsigned long perf, bestgenperf, bestxorperf, j0, j1;
135 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
136 const struct raid6_calls *const *algo;
137 const struct raid6_calls *best;
138
139 for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
140 if (!best || (*algo)->prefer >= best->prefer) {
141 if ((*algo)->valid && !(*algo)->valid())
142 continue;
143
144 perf = 0;
145
146 preempt_disable();
147 j0 = jiffies;
148 while ((j1 = jiffies) == j0)
149 cpu_relax();
150 while (time_before(jiffies,
151 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
152 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
153 perf++;
154 }
155 preempt_enable();
156
157 if (perf > bestgenperf) {
158 bestgenperf = perf;
159 best = *algo;
160 }
161 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
162 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
163
164 if (!(*algo)->xor_syndrome)
165 continue;
166
167 perf = 0;
168
169 preempt_disable();
170 j0 = jiffies;
171 while ((j1 = jiffies) == j0)
172 cpu_relax();
173 while (time_before(jiffies,
174 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
175 (*algo)->xor_syndrome(disks, start, stop,
176 PAGE_SIZE, *dptrs);
177 perf++;
178 }
179 preempt_enable();
180
181 if (best == *algo)
182 bestxorperf = perf;
183
184 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
185 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
186 }
187 }
188
189 if (best) {
190 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
191 best->name,
192 (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
193 if (best->xor_syndrome)
194 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
195 (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
196 raid6_call = *best;
197 } else
198 pr_err("raid6: Yikes! No algorithm found!\n");
199
200 return best;
201 }
202
203
204 /* Try to pick the best algorithm */
205 /* This code uses the gfmul table as convenient data set to abuse */
206
raid6_select_algo(void)207 int __init raid6_select_algo(void)
208 {
209 const int disks = (65536/PAGE_SIZE)+2;
210
211 const struct raid6_calls *gen_best;
212 const struct raid6_recov_calls *rec_best;
213 char *syndromes;
214 void *dptrs[(65536/PAGE_SIZE)+2];
215 int i;
216
217 for (i = 0; i < disks-2; i++)
218 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
219
220 /* Normal code - use a 2-page allocation to avoid D$ conflict */
221 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
222
223 if (!syndromes) {
224 pr_err("raid6: Yikes! No memory available.\n");
225 return -ENOMEM;
226 }
227
228 dptrs[disks-2] = syndromes;
229 dptrs[disks-1] = syndromes + PAGE_SIZE;
230
231 /* select raid gen_syndrome function */
232 gen_best = raid6_choose_gen(&dptrs, disks);
233
234 /* select raid recover functions */
235 rec_best = raid6_choose_recov();
236
237 free_pages((unsigned long)syndromes, 1);
238
239 return gen_best && rec_best ? 0 : -EINVAL;
240 }
241
raid6_exit(void)242 static void raid6_exit(void)
243 {
244 do { } while (0);
245 }
246
247 subsys_initcall(raid6_select_algo);
248 module_exit(raid6_exit);
249 MODULE_LICENSE("GPL");
250 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
251