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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, | |
93ed05e2 | 8 | * Boston MA 02111-1307, USA; either version 2 of the License, or |
1da177e4 LT |
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 | ||
f701d589 | 19 | #include <linux/raid/pq.h> |
5a0e3ad6 | 20 | #include <linux/gfp.h> |
1da177e4 LT |
21 | #ifndef __KERNEL__ |
22 | #include <sys/mman.h> | |
d7e70ba4 | 23 | #include <stdio.h> |
f701d589 DW |
24 | #else |
25 | #if !RAID6_USE_EMPTY_ZERO_PAGE | |
26 | /* In .bss so it's zeroed */ | |
27 | const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256))); | |
28 | EXPORT_SYMBOL(raid6_empty_zero_page); | |
29 | #endif | |
1da177e4 LT |
30 | #endif |
31 | ||
32 | struct raid6_calls raid6_call; | |
f701d589 | 33 | EXPORT_SYMBOL_GPL(raid6_call); |
1da177e4 | 34 | |
1da177e4 LT |
35 | const struct raid6_calls * const raid6_algos[] = { |
36 | &raid6_intx1, | |
37 | &raid6_intx2, | |
38 | &raid6_intx4, | |
39 | &raid6_intx8, | |
40 | #if defined(__ia64__) | |
41 | &raid6_intx16, | |
42 | &raid6_intx32, | |
43 | #endif | |
ca5cd877 | 44 | #if defined(__i386__) && !defined(__arch_um__) |
1da177e4 LT |
45 | &raid6_mmxx1, |
46 | &raid6_mmxx2, | |
47 | &raid6_sse1x1, | |
48 | &raid6_sse1x2, | |
49 | &raid6_sse2x1, | |
50 | &raid6_sse2x2, | |
51 | #endif | |
ca5cd877 | 52 | #if defined(__x86_64__) && !defined(__arch_um__) |
1da177e4 LT |
53 | &raid6_sse2x1, |
54 | &raid6_sse2x2, | |
55 | &raid6_sse2x4, | |
56 | #endif | |
57 | #ifdef CONFIG_ALTIVEC | |
58 | &raid6_altivec1, | |
59 | &raid6_altivec2, | |
60 | &raid6_altivec4, | |
61 | &raid6_altivec8, | |
62 | #endif | |
63 | NULL | |
64 | }; | |
65 | ||
66 | #ifdef __KERNEL__ | |
67 | #define RAID6_TIME_JIFFIES_LG2 4 | |
68 | #else | |
69 | /* Need more time to be stable in userspace */ | |
70 | #define RAID6_TIME_JIFFIES_LG2 9 | |
f701d589 | 71 | #define time_before(x, y) ((x) < (y)) |
1da177e4 LT |
72 | #endif |
73 | ||
74 | /* Try to pick the best algorithm */ | |
75 | /* This code uses the gfmul table as convenient data set to abuse */ | |
76 | ||
77 | int __init raid6_select_algo(void) | |
78 | { | |
79 | const struct raid6_calls * const * algo; | |
80 | const struct raid6_calls * best; | |
81 | char *syndromes; | |
82 | void *dptrs[(65536/PAGE_SIZE)+2]; | |
83 | int i, disks; | |
84 | unsigned long perf, bestperf; | |
85 | int bestprefer; | |
86 | unsigned long j0, j1; | |
87 | ||
88 | disks = (65536/PAGE_SIZE)+2; | |
89 | for ( i = 0 ; i < disks-2 ; i++ ) { | |
90 | dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i; | |
91 | } | |
92 | ||
93 | /* Normal code - use a 2-page allocation to avoid D$ conflict */ | |
94 | syndromes = (void *) __get_free_pages(GFP_KERNEL, 1); | |
95 | ||
96 | if ( !syndromes ) { | |
97 | printk("raid6: Yikes! No memory available.\n"); | |
98 | return -ENOMEM; | |
99 | } | |
100 | ||
101 | dptrs[disks-2] = syndromes; | |
102 | dptrs[disks-1] = syndromes + PAGE_SIZE; | |
103 | ||
104 | bestperf = 0; bestprefer = 0; best = NULL; | |
105 | ||
106 | for ( algo = raid6_algos ; *algo ; algo++ ) { | |
107 | if ( !(*algo)->valid || (*algo)->valid() ) { | |
108 | perf = 0; | |
109 | ||
110 | preempt_disable(); | |
111 | j0 = jiffies; | |
112 | while ( (j1 = jiffies) == j0 ) | |
113 | cpu_relax(); | |
62b0559a JL |
114 | while (time_before(jiffies, |
115 | j1 + (1<<RAID6_TIME_JIFFIES_LG2))) { | |
1da177e4 LT |
116 | (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs); |
117 | perf++; | |
118 | } | |
119 | preempt_enable(); | |
120 | ||
121 | if ( (*algo)->prefer > bestprefer || | |
122 | ((*algo)->prefer == bestprefer && | |
123 | perf > bestperf) ) { | |
124 | best = *algo; | |
125 | bestprefer = best->prefer; | |
126 | bestperf = perf; | |
127 | } | |
128 | printk("raid6: %-8s %5ld MB/s\n", (*algo)->name, | |
129 | (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2)); | |
130 | } | |
131 | } | |
132 | ||
a5d6839b | 133 | if (best) { |
1da177e4 LT |
134 | printk("raid6: using algorithm %s (%ld MB/s)\n", |
135 | best->name, | |
136 | (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2)); | |
a5d6839b AB |
137 | raid6_call = *best; |
138 | } else | |
1da177e4 LT |
139 | printk("raid6: Yikes! No algorithm found!\n"); |
140 | ||
1da177e4 LT |
141 | free_pages((unsigned long)syndromes, 1); |
142 | ||
143 | return best ? 0 : -EINVAL; | |
144 | } | |
f701d589 DW |
145 | |
146 | static void raid6_exit(void) | |
147 | { | |
148 | do { } while (0); | |
149 | } | |
150 | ||
151 | subsys_initcall(raid6_select_algo); | |
152 | module_exit(raid6_exit); | |
153 | MODULE_LICENSE("GPL"); | |
0efb9e61 | 154 | MODULE_DESCRIPTION("RAID6 Q-syndrome calculations"); |