Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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(__i386__) && !defined(__arch_um__)
38#ifdef CONFIG_AS_AVX512
39 &raid6_avx512x2,
40 &raid6_avx512x1,
41#endif
42#ifdef CONFIG_AS_AVX2
43 &raid6_avx2x2,
44 &raid6_avx2x1,
45#endif
46 &raid6_sse2x2,
47 &raid6_sse2x1,
48 &raid6_sse1x2,
49 &raid6_sse1x1,
50 &raid6_mmxx2,
51 &raid6_mmxx1,
52#endif
53#if defined(__x86_64__) && !defined(__arch_um__)
54#ifdef CONFIG_AS_AVX512
55 &raid6_avx512x4,
56 &raid6_avx512x2,
57 &raid6_avx512x1,
58#endif
59#ifdef CONFIG_AS_AVX2
60 &raid6_avx2x4,
61 &raid6_avx2x2,
62 &raid6_avx2x1,
63#endif
64 &raid6_sse2x4,
65 &raid6_sse2x2,
66 &raid6_sse2x1,
67#endif
68#ifdef CONFIG_ALTIVEC
69 &raid6_vpermxor8,
70 &raid6_vpermxor4,
71 &raid6_vpermxor2,
72 &raid6_vpermxor1,
73 &raid6_altivec8,
74 &raid6_altivec4,
75 &raid6_altivec2,
76 &raid6_altivec1,
77#endif
78#if defined(CONFIG_S390)
79 &raid6_s390vx8,
80#endif
81#ifdef CONFIG_KERNEL_MODE_NEON
82 &raid6_neonx8,
83 &raid6_neonx4,
84 &raid6_neonx2,
85 &raid6_neonx1,
86#endif
87#if defined(__ia64__)
88 &raid6_intx32,
89 &raid6_intx16,
90#endif
91 &raid6_intx8,
92 &raid6_intx4,
93 &raid6_intx2,
94 &raid6_intx1,
95 NULL
96};
97
98void (*raid6_2data_recov)(int, size_t, int, int, void **);
99EXPORT_SYMBOL_GPL(raid6_2data_recov);
100
101void (*raid6_datap_recov)(int, size_t, int, void **);
102EXPORT_SYMBOL_GPL(raid6_datap_recov);
103
104const 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
132static 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
153static 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 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
167 best = *algo;
168 break;
169 }
170
171 perf = 0;
172
173 preempt_disable();
174 j0 = jiffies;
175 while ((j1 = jiffies) == j0)
176 cpu_relax();
177 while (time_before(jiffies,
178 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
179 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
180 perf++;
181 }
182 preempt_enable();
183
184 if (perf > bestgenperf) {
185 bestgenperf = perf;
186 best = *algo;
187 }
188 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
189 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
190
191 if (!(*algo)->xor_syndrome)
192 continue;
193
194 perf = 0;
195
196 preempt_disable();
197 j0 = jiffies;
198 while ((j1 = jiffies) == j0)
199 cpu_relax();
200 while (time_before(jiffies,
201 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
202 (*algo)->xor_syndrome(disks, start, stop,
203 PAGE_SIZE, *dptrs);
204 perf++;
205 }
206 preempt_enable();
207
208 if (best == *algo)
209 bestxorperf = perf;
210
211 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
212 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
213 }
214 }
215
216 if (best) {
217 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
218 best->name,
219 (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
220 if (best->xor_syndrome)
221 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
222 (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
223 raid6_call = *best;
224 } else
225 pr_err("raid6: Yikes! No algorithm found!\n");
226
227 return best;
228}
229
230
231/* Try to pick the best algorithm */
232/* This code uses the gfmul table as convenient data set to abuse */
233
234int __init raid6_select_algo(void)
235{
236 const int disks = (65536/PAGE_SIZE)+2;
237
238 const struct raid6_calls *gen_best;
239 const struct raid6_recov_calls *rec_best;
240 char *syndromes;
241 void *dptrs[(65536/PAGE_SIZE)+2];
242 int i;
243
244 for (i = 0; i < disks-2; i++)
245 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
246
247 /* Normal code - use a 2-page allocation to avoid D$ conflict */
248 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
249
250 if (!syndromes) {
251 pr_err("raid6: Yikes! No memory available.\n");
252 return -ENOMEM;
253 }
254
255 dptrs[disks-2] = syndromes;
256 dptrs[disks-1] = syndromes + PAGE_SIZE;
257
258 /* select raid gen_syndrome function */
259 gen_best = raid6_choose_gen(&dptrs, disks);
260
261 /* select raid recover functions */
262 rec_best = raid6_choose_recov();
263
264 free_pages((unsigned long)syndromes, 1);
265
266 return gen_best && rec_best ? 0 : -EINVAL;
267}
268
269static void raid6_exit(void)
270{
271 do { } while (0);
272}
273
274subsys_initcall(raid6_select_algo);
275module_exit(raid6_exit);
276MODULE_LICENSE("GPL");
277MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");