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