xref: /kernel/linux/linux-5.10/lib/raid6/algos.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* -*- linux-c -*- ------------------------------------------------------- *
3 *
4 *   Copyright 2002 H. Peter Anvin - All Rights Reserved
5 *
6 * ----------------------------------------------------------------------- */
7
8/*
9 * raid6/algos.c
10 *
11 * Algorithm list and algorithm selection for RAID-6
12 */
13
14#include <linux/raid/pq.h>
15#ifndef __KERNEL__
16#include <sys/mman.h>
17#include <stdio.h>
18#else
19#include <linux/module.h>
20#include <linux/gfp.h>
21#if !RAID6_USE_EMPTY_ZERO_PAGE
22/* In .bss so it's zeroed */
23const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
24EXPORT_SYMBOL(raid6_empty_zero_page);
25#endif
26#endif
27
28struct raid6_calls raid6_call;
29EXPORT_SYMBOL_GPL(raid6_call);
30
31const struct raid6_calls * const raid6_algos[] = {
32#if defined(__i386__) && !defined(__arch_um__)
33#ifdef CONFIG_AS_AVX512
34	&raid6_avx512x2,
35	&raid6_avx512x1,
36#endif
37	&raid6_avx2x2,
38	&raid6_avx2x1,
39	&raid6_sse2x2,
40	&raid6_sse2x1,
41	&raid6_sse1x2,
42	&raid6_sse1x1,
43	&raid6_mmxx2,
44	&raid6_mmxx1,
45#endif
46#if defined(__x86_64__) && !defined(__arch_um__)
47#ifdef CONFIG_AS_AVX512
48	&raid6_avx512x4,
49	&raid6_avx512x2,
50	&raid6_avx512x1,
51#endif
52	&raid6_avx2x4,
53	&raid6_avx2x2,
54	&raid6_avx2x1,
55	&raid6_sse2x4,
56	&raid6_sse2x2,
57	&raid6_sse2x1,
58#endif
59#ifdef CONFIG_ALTIVEC
60	&raid6_vpermxor8,
61	&raid6_vpermxor4,
62	&raid6_vpermxor2,
63	&raid6_vpermxor1,
64	&raid6_altivec8,
65	&raid6_altivec4,
66	&raid6_altivec2,
67	&raid6_altivec1,
68#endif
69#if defined(CONFIG_S390)
70	&raid6_s390vx8,
71#endif
72#ifdef CONFIG_KERNEL_MODE_NEON
73	&raid6_neonx8,
74	&raid6_neonx4,
75	&raid6_neonx2,
76	&raid6_neonx1,
77#endif
78#ifdef CONFIG_LOONGARCH
79#ifdef CONFIG_CPU_HAS_LASX
80	&raid6_lasx,
81#endif
82#ifdef CONFIG_CPU_HAS_LSX
83	&raid6_lsx,
84#endif
85#endif
86#if defined(__ia64__)
87	&raid6_intx32,
88	&raid6_intx16,
89#endif
90	&raid6_intx8,
91	&raid6_intx4,
92	&raid6_intx2,
93	&raid6_intx1,
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_X86
105#ifdef CONFIG_AS_AVX512
106	&raid6_recov_avx512,
107#endif
108	&raid6_recov_avx2,
109	&raid6_recov_ssse3,
110#endif
111#ifdef CONFIG_S390
112	&raid6_recov_s390xc,
113#endif
114#if defined(CONFIG_KERNEL_MODE_NEON)
115	&raid6_recov_neon,
116#endif
117#ifdef CONFIG_LOONGARCH
118#ifdef CONFIG_CPU_HAS_LASX
119	&raid6_recov_lasx,
120#endif
121#ifdef CONFIG_CPU_HAS_LSX
122	&raid6_recov_lsx,
123#endif
124#endif
125	&raid6_recov_intx1,
126	NULL
127};
128
129#ifdef __KERNEL__
130#define RAID6_TIME_JIFFIES_LG2	4
131#else
132/* Need more time to be stable in userspace */
133#define RAID6_TIME_JIFFIES_LG2	9
134#define time_before(x, y) ((x) < (y))
135#endif
136
137#define RAID6_TEST_DISKS	8
138#define RAID6_TEST_DISKS_ORDER	3
139
140static inline const struct raid6_recov_calls *raid6_choose_recov(void)
141{
142	const struct raid6_recov_calls *const *algo;
143	const struct raid6_recov_calls *best;
144
145	for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
146		if (!best || (*algo)->priority > best->priority)
147			if (!(*algo)->valid || (*algo)->valid())
148				best = *algo;
149
150	if (best) {
151		raid6_2data_recov = best->data2;
152		raid6_datap_recov = best->datap;
153
154		pr_info("raid6: using %s recovery algorithm\n", best->name);
155	} else
156		pr_err("raid6: Yikes! No recovery algorithm found!\n");
157
158	return best;
159}
160
161static inline const struct raid6_calls *raid6_choose_gen(
162	void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
163{
164	unsigned long perf, bestgenperf, bestxorperf, j0, j1;
165	int start = (disks>>1)-1, stop = disks-3;	/* work on the second half of the disks */
166	const struct raid6_calls *const *algo;
167	const struct raid6_calls *best;
168
169	for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
170		if (!best || (*algo)->prefer >= best->prefer) {
171			if ((*algo)->valid && !(*algo)->valid())
172				continue;
173
174			if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
175				best = *algo;
176				break;
177			}
178
179			perf = 0;
180
181			preempt_disable();
182			j0 = jiffies;
183			while ((j1 = jiffies) == j0)
184				cpu_relax();
185			while (time_before(jiffies,
186					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
187				(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
188				perf++;
189			}
190			preempt_enable();
191
192			if (perf > bestgenperf) {
193				bestgenperf = perf;
194				best = *algo;
195			}
196			pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
197				(perf * HZ * (disks-2)) >>
198				(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
199
200			if (!(*algo)->xor_syndrome)
201				continue;
202
203			perf = 0;
204
205			preempt_disable();
206			j0 = jiffies;
207			while ((j1 = jiffies) == j0)
208				cpu_relax();
209			while (time_before(jiffies,
210					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
211				(*algo)->xor_syndrome(disks, start, stop,
212						      PAGE_SIZE, *dptrs);
213				perf++;
214			}
215			preempt_enable();
216
217			if (best == *algo)
218				bestxorperf = perf;
219
220			pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
221				(perf * HZ * (disks-2)) >>
222				(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
223		}
224	}
225
226	if (best) {
227		if (IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
228			pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
229				best->name,
230				(bestgenperf * HZ * (disks-2)) >>
231				(20 - PAGE_SHIFT+RAID6_TIME_JIFFIES_LG2));
232			if (best->xor_syndrome)
233				pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
234					(bestxorperf * HZ * (disks-2)) >>
235					(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
236		} else
237			pr_info("raid6: skip pq benchmark and using algorithm %s\n",
238				best->name);
239		raid6_call = *best;
240	} else
241		pr_err("raid6: Yikes!  No algorithm found!\n");
242
243	return best;
244}
245
246
247/* Try to pick the best algorithm */
248/* This code uses the gfmul table as convenient data set to abuse */
249
250int __init raid6_select_algo(void)
251{
252	const int disks = RAID6_TEST_DISKS;
253
254	const struct raid6_calls *gen_best;
255	const struct raid6_recov_calls *rec_best;
256	char *disk_ptr, *p;
257	void *dptrs[RAID6_TEST_DISKS];
258	int i, cycle;
259
260	/* prepare the buffer and fill it circularly with gfmul table */
261	disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
262	if (!disk_ptr) {
263		pr_err("raid6: Yikes!  No memory available.\n");
264		return -ENOMEM;
265	}
266
267	p = disk_ptr;
268	for (i = 0; i < disks; i++)
269		dptrs[i] = p + PAGE_SIZE * i;
270
271	cycle = ((disks - 2) * PAGE_SIZE) / 65536;
272	for (i = 0; i < cycle; i++) {
273		memcpy(p, raid6_gfmul, 65536);
274		p += 65536;
275	}
276
277	if ((disks - 2) * PAGE_SIZE % 65536)
278		memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
279
280	/* select raid gen_syndrome function */
281	gen_best = raid6_choose_gen(&dptrs, disks);
282
283	/* select raid recover functions */
284	rec_best = raid6_choose_recov();
285
286	free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
287
288	return gen_best && rec_best ? 0 : -EINVAL;
289}
290
291static void raid6_exit(void)
292{
293	do { } while (0);
294}
295
296subsys_initcall(raid6_select_algo);
297module_exit(raid6_exit);
298MODULE_LICENSE("GPL");
299MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
300