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 * Bostom 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 "raid6.h"
20#ifndef __KERNEL__
21#include <sys/mman.h>
22#endif
23
24struct raid6_calls raid6_call;
25
26/* Various routine sets */
27extern const struct raid6_calls raid6_intx1;
28extern const struct raid6_calls raid6_intx2;
29extern const struct raid6_calls raid6_intx4;
30extern const struct raid6_calls raid6_intx8;
31extern const struct raid6_calls raid6_intx16;
32extern const struct raid6_calls raid6_intx32;
33extern const struct raid6_calls raid6_mmxx1;
34extern const struct raid6_calls raid6_mmxx2;
35extern const struct raid6_calls raid6_sse1x1;
36extern const struct raid6_calls raid6_sse1x2;
37extern const struct raid6_calls raid6_sse2x1;
38extern const struct raid6_calls raid6_sse2x2;
39extern const struct raid6_calls raid6_sse2x4;
40extern const struct raid6_calls raid6_altivec1;
41extern const struct raid6_calls raid6_altivec2;
42extern const struct raid6_calls raid6_altivec4;
43extern const struct raid6_calls raid6_altivec8;
44
45const struct raid6_calls * const raid6_algos[] = {
46 &raid6_intx1,
47 &raid6_intx2,
48 &raid6_intx4,
49 &raid6_intx8,
50#if defined(__ia64__)
51 &raid6_intx16,
52 &raid6_intx32,
53#endif
54#if defined(__i386__)
55 &raid6_mmxx1,
56 &raid6_mmxx2,
57 &raid6_sse1x1,
58 &raid6_sse1x2,
59 &raid6_sse2x1,
60 &raid6_sse2x2,
61#endif
62#if defined(__x86_64__)
63 &raid6_sse2x1,
64 &raid6_sse2x2,
65 &raid6_sse2x4,
66#endif
67#ifdef CONFIG_ALTIVEC
68 &raid6_altivec1,
69 &raid6_altivec2,
70 &raid6_altivec4,
71 &raid6_altivec8,
72#endif
73 NULL
74};
75
76#ifdef __KERNEL__
77#define RAID6_TIME_JIFFIES_LG2 4
78#else
79/* Need more time to be stable in userspace */
80#define RAID6_TIME_JIFFIES_LG2 9
81#endif
82
83/* Try to pick the best algorithm */
84/* This code uses the gfmul table as convenient data set to abuse */
85
86int __init raid6_select_algo(void)
87{
88 const struct raid6_calls * const * algo;
89 const struct raid6_calls * best;
90 char *syndromes;
91 void *dptrs[(65536/PAGE_SIZE)+2];
92 int i, disks;
93 unsigned long perf, bestperf;
94 int bestprefer;
95 unsigned long j0, j1;
96
97 disks = (65536/PAGE_SIZE)+2;
98 for ( i = 0 ; i < disks-2 ; i++ ) {
99 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
100 }
101
102 /* Normal code - use a 2-page allocation to avoid D$ conflict */
103 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
104
105 if ( !syndromes ) {
106 printk("raid6: Yikes! No memory available.\n");
107 return -ENOMEM;
108 }
109
110 dptrs[disks-2] = syndromes;
111 dptrs[disks-1] = syndromes + PAGE_SIZE;
112
113 bestperf = 0; bestprefer = 0; best = NULL;
114
115 for ( algo = raid6_algos ; *algo ; algo++ ) {
116 if ( !(*algo)->valid || (*algo)->valid() ) {
117 perf = 0;
118
119 preempt_disable();
120 j0 = jiffies;
121 while ( (j1 = jiffies) == j0 )
122 cpu_relax();
123 while ( (jiffies-j1) < (1 << RAID6_TIME_JIFFIES_LG2) ) {
124 (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
125 perf++;
126 }
127 preempt_enable();
128
129 if ( (*algo)->prefer > bestprefer ||
130 ((*algo)->prefer == bestprefer &&
131 perf > bestperf) ) {
132 best = *algo;
133 bestprefer = best->prefer;
134 bestperf = perf;
135 }
136 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
137 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
138 }
139 }
140
141 if ( best )
142 printk("raid6: using algorithm %s (%ld MB/s)\n",
143 best->name,
144 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
145 else
146 printk("raid6: Yikes! No algorithm found!\n");
147
148 raid6_call = *best;
149
150 free_pages((unsigned long)syndromes, 1);
151
152 return best ? 0 : -EINVAL;
153}