1 /* -*- linux-c -*- ------------------------------------------------------- *
3 * Copyright 2002 H. Peter Anvin - All Rights Reserved
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.
11 * ----------------------------------------------------------------------- */
16 * Algorithm list and algorithm selection for RAID-6
19 #include <linux/raid/pq.h>
24 #include <linux/module.h>
25 #include <linux/gfp.h>
26 #if !RAID6_USE_EMPTY_ZERO_PAGE
27 /* In .bss so it's zeroed */
28 const char raid6_empty_zero_page
[PAGE_SIZE
] __attribute__((aligned(256)));
29 EXPORT_SYMBOL(raid6_empty_zero_page
);
33 struct raid6_calls raid6_call
;
34 EXPORT_SYMBOL_GPL(raid6_call
);
36 const struct raid6_calls
* const raid6_algos
[] = {
41 #if defined(__i386__) && !defined(__arch_um__)
53 #if defined(__x86_64__) && !defined(__arch_um__)
73 #ifdef CONFIG_KERNEL_MODE_NEON
82 void (*raid6_2data_recov
)(int, size_t, int, int, void **);
83 EXPORT_SYMBOL_GPL(raid6_2data_recov
);
85 void (*raid6_datap_recov
)(int, size_t, int, void **);
86 EXPORT_SYMBOL_GPL(raid6_datap_recov
);
88 const struct raid6_recov_calls
*const raid6_recov_algos
[] = {
89 #if (defined(__i386__) || defined(__x86_64__)) && !defined(__arch_um__)
100 #define RAID6_TIME_JIFFIES_LG2 4
102 /* Need more time to be stable in userspace */
103 #define RAID6_TIME_JIFFIES_LG2 9
104 #define time_before(x, y) ((x) < (y))
107 static inline const struct raid6_recov_calls
*raid6_choose_recov(void)
109 const struct raid6_recov_calls
*const *algo
;
110 const struct raid6_recov_calls
*best
;
112 for (best
= NULL
, algo
= raid6_recov_algos
; *algo
; algo
++)
113 if (!best
|| (*algo
)->priority
> best
->priority
)
114 if (!(*algo
)->valid
|| (*algo
)->valid())
118 raid6_2data_recov
= best
->data2
;
119 raid6_datap_recov
= best
->datap
;
121 printk("raid6: using %s recovery algorithm\n", best
->name
);
123 printk("raid6: Yikes! No recovery algorithm found!\n");
128 static inline const struct raid6_calls
*raid6_choose_gen(
129 void *(*const dptrs
)[(65536/PAGE_SIZE
)+2], const int disks
)
131 unsigned long perf
, bestperf
, j0
, j1
;
132 const struct raid6_calls
*const *algo
;
133 const struct raid6_calls
*best
;
135 for (bestperf
= 0, best
= NULL
, algo
= raid6_algos
; *algo
; algo
++) {
136 if (!best
|| (*algo
)->prefer
>= best
->prefer
) {
137 if ((*algo
)->valid
&& !(*algo
)->valid())
144 while ((j1
= jiffies
) == j0
)
146 while (time_before(jiffies
,
147 j1
+ (1<<RAID6_TIME_JIFFIES_LG2
))) {
148 (*algo
)->gen_syndrome(disks
, PAGE_SIZE
, *dptrs
);
153 if (perf
> bestperf
) {
157 printk("raid6: %-8s %5ld MB/s\n", (*algo
)->name
,
158 (perf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
163 printk("raid6: using algorithm %s (%ld MB/s)\n",
165 (bestperf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
168 printk("raid6: Yikes! No algorithm found!\n");
174 /* Try to pick the best algorithm */
175 /* This code uses the gfmul table as convenient data set to abuse */
177 int __init
raid6_select_algo(void)
179 const int disks
= (65536/PAGE_SIZE
)+2;
181 const struct raid6_calls
*gen_best
;
182 const struct raid6_recov_calls
*rec_best
;
184 void *dptrs
[(65536/PAGE_SIZE
)+2];
187 for (i
= 0; i
< disks
-2; i
++)
188 dptrs
[i
] = ((char *)raid6_gfmul
) + PAGE_SIZE
*i
;
190 /* Normal code - use a 2-page allocation to avoid D$ conflict */
191 syndromes
= (void *) __get_free_pages(GFP_KERNEL
, 1);
194 printk("raid6: Yikes! No memory available.\n");
198 dptrs
[disks
-2] = syndromes
;
199 dptrs
[disks
-1] = syndromes
+ PAGE_SIZE
;
201 /* select raid gen_syndrome function */
202 gen_best
= raid6_choose_gen(&dptrs
, disks
);
204 /* select raid recover functions */
205 rec_best
= raid6_choose_recov();
207 free_pages((unsigned long)syndromes
, 1);
209 return gen_best
&& rec_best
? 0 : -EINVAL
;
212 static void raid6_exit(void)
217 subsys_initcall(raid6_select_algo
);
218 module_exit(raid6_exit
);
219 MODULE_LICENSE("GPL");
220 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
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