Linux kernel mirror (for testing)
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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 * raid6algos.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#if !RAID6_USE_EMPTY_ZERO_PAGE
25/* In .bss so it's zeroed */
26const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
27EXPORT_SYMBOL(raid6_empty_zero_page);
28#endif
29#endif
30
31struct raid6_calls raid6_call;
32EXPORT_SYMBOL_GPL(raid6_call);
33
34/* Various routine sets */
35extern const struct raid6_calls raid6_intx1;
36extern const struct raid6_calls raid6_intx2;
37extern const struct raid6_calls raid6_intx4;
38extern const struct raid6_calls raid6_intx8;
39extern const struct raid6_calls raid6_intx16;
40extern const struct raid6_calls raid6_intx32;
41extern const struct raid6_calls raid6_mmxx1;
42extern const struct raid6_calls raid6_mmxx2;
43extern const struct raid6_calls raid6_sse1x1;
44extern const struct raid6_calls raid6_sse1x2;
45extern const struct raid6_calls raid6_sse2x1;
46extern const struct raid6_calls raid6_sse2x2;
47extern const struct raid6_calls raid6_sse2x4;
48extern const struct raid6_calls raid6_altivec1;
49extern const struct raid6_calls raid6_altivec2;
50extern const struct raid6_calls raid6_altivec4;
51extern const struct raid6_calls raid6_altivec8;
52
53const struct raid6_calls * const raid6_algos[] = {
54 &raid6_intx1,
55 &raid6_intx2,
56 &raid6_intx4,
57 &raid6_intx8,
58#if defined(__ia64__)
59 &raid6_intx16,
60 &raid6_intx32,
61#endif
62#if defined(__i386__) && !defined(__arch_um__)
63 &raid6_mmxx1,
64 &raid6_mmxx2,
65 &raid6_sse1x1,
66 &raid6_sse1x2,
67 &raid6_sse2x1,
68 &raid6_sse2x2,
69#endif
70#if defined(__x86_64__) && !defined(__arch_um__)
71 &raid6_sse2x1,
72 &raid6_sse2x2,
73 &raid6_sse2x4,
74#endif
75#ifdef CONFIG_ALTIVEC
76 &raid6_altivec1,
77 &raid6_altivec2,
78 &raid6_altivec4,
79 &raid6_altivec8,
80#endif
81 NULL
82};
83
84#ifdef __KERNEL__
85#define RAID6_TIME_JIFFIES_LG2 4
86#else
87/* Need more time to be stable in userspace */
88#define RAID6_TIME_JIFFIES_LG2 9
89#define time_before(x, y) ((x) < (y))
90#endif
91
92/* Try to pick the best algorithm */
93/* This code uses the gfmul table as convenient data set to abuse */
94
95int __init raid6_select_algo(void)
96{
97 const struct raid6_calls * const * algo;
98 const struct raid6_calls * best;
99 char *syndromes;
100 void *dptrs[(65536/PAGE_SIZE)+2];
101 int i, disks;
102 unsigned long perf, bestperf;
103 int bestprefer;
104 unsigned long j0, j1;
105
106 disks = (65536/PAGE_SIZE)+2;
107 for ( i = 0 ; i < disks-2 ; i++ ) {
108 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
109 }
110
111 /* Normal code - use a 2-page allocation to avoid D$ conflict */
112 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
113
114 if ( !syndromes ) {
115 printk("raid6: Yikes! No memory available.\n");
116 return -ENOMEM;
117 }
118
119 dptrs[disks-2] = syndromes;
120 dptrs[disks-1] = syndromes + PAGE_SIZE;
121
122 bestperf = 0; bestprefer = 0; best = NULL;
123
124 for ( algo = raid6_algos ; *algo ; algo++ ) {
125 if ( !(*algo)->valid || (*algo)->valid() ) {
126 perf = 0;
127
128 preempt_disable();
129 j0 = jiffies;
130 while ( (j1 = jiffies) == j0 )
131 cpu_relax();
132 while (time_before(jiffies,
133 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
134 (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
135 perf++;
136 }
137 preempt_enable();
138
139 if ( (*algo)->prefer > bestprefer ||
140 ((*algo)->prefer == bestprefer &&
141 perf > bestperf) ) {
142 best = *algo;
143 bestprefer = best->prefer;
144 bestperf = perf;
145 }
146 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
147 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
148 }
149 }
150
151 if (best) {
152 printk("raid6: using algorithm %s (%ld MB/s)\n",
153 best->name,
154 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
155 raid6_call = *best;
156 } else
157 printk("raid6: Yikes! No algorithm found!\n");
158
159 free_pages((unsigned long)syndromes, 1);
160
161 return best ? 0 : -EINVAL;
162}
163
164static void raid6_exit(void)
165{
166 do { } while (0);
167}
168
169subsys_initcall(raid6_select_algo);
170module_exit(raid6_exit);
171MODULE_LICENSE("GPL");