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#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
85void (*raid6_2data_recov)(int, size_t, int, int, void **);
86EXPORT_SYMBOL_GPL(raid6_2data_recov);
87
88void (*raid6_datap_recov)(int, size_t, int, void **);
89EXPORT_SYMBOL_GPL(raid6_datap_recov);
90
91const 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
110static 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
131static 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
207int __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
242static void raid6_exit(void)
243{
244	do { } while (0);
245}
246
247subsys_initcall(raid6_select_algo);
248module_exit(raid6_exit);
249MODULE_LICENSE("GPL");
250MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
251