projects/linux·blob v4.13 · refs

268 lines · 6.2 KiB

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 */
28const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
29EXPORT_SYMBOL(raid6_empty_zero_page);
30#endif
31#endif
32
33struct raid6_calls raid6_call;
34EXPORT_SYMBOL_GPL(raid6_call);
35
36const 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#endif
78#if defined(CONFIG_TILEGX)
79 &raid6_tilegx8,
80#endif
81#if defined(CONFIG_S390)
82 &raid6_s390vx8,
83#endif
84 &raid6_intx1,
85 &raid6_intx2,
86 &raid6_intx4,
87 &raid6_intx8,
88#ifdef CONFIG_KERNEL_MODE_NEON
89 &raid6_neonx1,
90 &raid6_neonx2,
91 &raid6_neonx4,
92 &raid6_neonx8,
93#endif
94 NULL
95};
96
97void (*raid6_2data_recov)(int, size_t, int, int, void **);
98EXPORT_SYMBOL_GPL(raid6_2data_recov);
99
100void (*raid6_datap_recov)(int, size_t, int, void **);
101EXPORT_SYMBOL_GPL(raid6_datap_recov);
102
103const struct raid6_recov_calls *const raid6_recov_algos[] = {
104#ifdef CONFIG_AS_AVX512
105 &raid6_recov_avx512,
106#endif
107#ifdef CONFIG_AS_AVX2
108 &raid6_recov_avx2,
109#endif
110#ifdef CONFIG_AS_SSSE3
111 &raid6_recov_ssse3,
112#endif
113#ifdef CONFIG_S390
114 &raid6_recov_s390xc,
115#endif
116 &raid6_recov_intx1,
117 NULL
118};
119
120#ifdef __KERNEL__
121#define RAID6_TIME_JIFFIES_LG2 4
122#else
123/* Need more time to be stable in userspace */
124#define RAID6_TIME_JIFFIES_LG2 9
125#define time_before(x, y) ((x) < (y))
126#endif
127
128static inline const struct raid6_recov_calls *raid6_choose_recov(void)
129{
130 const struct raid6_recov_calls *const *algo;
131 const struct raid6_recov_calls *best;
132
133 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
134 if (!best || (*algo)->priority > best->priority)
135 if (!(*algo)->valid || (*algo)->valid())
136 best = *algo;
137
138 if (best) {
139 raid6_2data_recov = best->data2;
140 raid6_datap_recov = best->datap;
141
142 pr_info("raid6: using %s recovery algorithm\n", best->name);
143 } else
144 pr_err("raid6: Yikes! No recovery algorithm found!\n");
145
146 return best;
147}
148
149static inline const struct raid6_calls *raid6_choose_gen(
150 void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
151{
152 unsigned long perf, bestgenperf, bestxorperf, j0, j1;
153 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
154 const struct raid6_calls *const *algo;
155 const struct raid6_calls *best;
156
157 for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
158 if (!best || (*algo)->prefer >= best->prefer) {
159 if ((*algo)->valid && !(*algo)->valid())
160 continue;
161
162 perf = 0;
163
164 preempt_disable();
165 j0 = jiffies;
166 while ((j1 = jiffies) == j0)
167 cpu_relax();
168 while (time_before(jiffies,
169 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
170 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
171 perf++;
172 }
173 preempt_enable();
174
175 if (perf > bestgenperf) {
176 bestgenperf = perf;
177 best = *algo;
178 }
179 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
180 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
181
182 if (!(*algo)->xor_syndrome)
183 continue;
184
185 perf = 0;
186
187 preempt_disable();
188 j0 = jiffies;
189 while ((j1 = jiffies) == j0)
190 cpu_relax();
191 while (time_before(jiffies,
192 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
193 (*algo)->xor_syndrome(disks, start, stop,
194 PAGE_SIZE, *dptrs);
195 perf++;
196 }
197 preempt_enable();
198
199 if (best == *algo)
200 bestxorperf = perf;
201
202 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
203 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
204 }
205 }
206
207 if (best) {
208 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
209 best->name,
210 (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
211 if (best->xor_syndrome)
212 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
213 (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
214 raid6_call = *best;
215 } else
216 pr_err("raid6: Yikes! No algorithm found!\n");
217
218 return best;
219}
220
221
222/* Try to pick the best algorithm */
223/* This code uses the gfmul table as convenient data set to abuse */
224
225int __init raid6_select_algo(void)
226{
227 const int disks = (65536/PAGE_SIZE)+2;
228
229 const struct raid6_calls *gen_best;
230 const struct raid6_recov_calls *rec_best;
231 char *syndromes;
232 void *dptrs[(65536/PAGE_SIZE)+2];
233 int i;
234
235 for (i = 0; i < disks-2; i++)
236 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
237
238 /* Normal code - use a 2-page allocation to avoid D$ conflict */
239 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
240
241 if (!syndromes) {
242 pr_err("raid6: Yikes! No memory available.\n");
243 return -ENOMEM;
244 }
245
246 dptrs[disks-2] = syndromes;
247 dptrs[disks-1] = syndromes + PAGE_SIZE;
248
249 /* select raid gen_syndrome function */
250 gen_best = raid6_choose_gen(&dptrs, disks);
251
252 /* select raid recover functions */
253 rec_best = raid6_choose_recov();
254
255 free_pages((unsigned long)syndromes, 1);
256
257 return gen_best && rec_best ? 0 : -EINVAL;
258}
259
260static void raid6_exit(void)
261{
262 do { } while (0);
263}
264
265subsys_initcall(raid6_select_algo);
266module_exit(raid6_exit);
267MODULE_LICENSE("GPL");
268MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");