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__)
69 #if defined(CONFIG_TILEGX)
72 #if defined(CONFIG_S390)
79 #ifdef CONFIG_KERNEL_MODE_NEON
88 void (*raid6_2data_recov
)(int, size_t, int, int, void **);
89 EXPORT_SYMBOL_GPL(raid6_2data_recov
);
91 void (*raid6_datap_recov
)(int, size_t, int, void **);
92 EXPORT_SYMBOL_GPL(raid6_datap_recov
);
94 const struct raid6_recov_calls
*const raid6_recov_algos
[] = {
98 #ifdef CONFIG_AS_SSSE3
109 #define RAID6_TIME_JIFFIES_LG2 4
111 /* Need more time to be stable in userspace */
112 #define RAID6_TIME_JIFFIES_LG2 9
113 #define time_before(x, y) ((x) < (y))
116 static inline const struct raid6_recov_calls
*raid6_choose_recov(void)
118 const struct raid6_recov_calls
*const *algo
;
119 const struct raid6_recov_calls
*best
;
121 for (best
= NULL
, algo
= raid6_recov_algos
; *algo
; algo
++)
122 if (!best
|| (*algo
)->priority
> best
->priority
)
123 if (!(*algo
)->valid
|| (*algo
)->valid())
127 raid6_2data_recov
= best
->data2
;
128 raid6_datap_recov
= best
->datap
;
130 pr_info("raid6: using %s recovery algorithm\n", best
->name
);
132 pr_err("raid6: Yikes! No recovery algorithm found!\n");
137 static inline const struct raid6_calls
*raid6_choose_gen(
138 void *(*const dptrs
)[(65536/PAGE_SIZE
)+2], const int disks
)
140 unsigned long perf
, bestgenperf
, bestxorperf
, j0
, j1
;
141 int start
= (disks
>>1)-1, stop
= disks
-3; /* work on the second half of the disks */
142 const struct raid6_calls
*const *algo
;
143 const struct raid6_calls
*best
;
145 for (bestgenperf
= 0, bestxorperf
= 0, best
= NULL
, algo
= raid6_algos
; *algo
; algo
++) {
146 if (!best
|| (*algo
)->prefer
>= best
->prefer
) {
147 if ((*algo
)->valid
&& !(*algo
)->valid())
154 while ((j1
= jiffies
) == j0
)
156 while (time_before(jiffies
,
157 j1
+ (1<<RAID6_TIME_JIFFIES_LG2
))) {
158 (*algo
)->gen_syndrome(disks
, PAGE_SIZE
, *dptrs
);
163 if (perf
> bestgenperf
) {
167 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo
)->name
,
168 (perf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
170 if (!(*algo
)->xor_syndrome
)
177 while ((j1
= jiffies
) == j0
)
179 while (time_before(jiffies
,
180 j1
+ (1<<RAID6_TIME_JIFFIES_LG2
))) {
181 (*algo
)->xor_syndrome(disks
, start
, stop
,
190 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo
)->name
,
191 (perf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
+1));
196 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
198 (bestgenperf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
199 if (best
->xor_syndrome
)
200 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
201 (bestxorperf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
+1));
204 pr_err("raid6: Yikes! No algorithm found!\n");
210 /* Try to pick the best algorithm */
211 /* This code uses the gfmul table as convenient data set to abuse */
213 int __init
raid6_select_algo(void)
215 const int disks
= (65536/PAGE_SIZE
)+2;
217 const struct raid6_calls
*gen_best
;
218 const struct raid6_recov_calls
*rec_best
;
220 void *dptrs
[(65536/PAGE_SIZE
)+2];
223 for (i
= 0; i
< disks
-2; i
++)
224 dptrs
[i
] = ((char *)raid6_gfmul
) + PAGE_SIZE
*i
;
226 /* Normal code - use a 2-page allocation to avoid D$ conflict */
227 syndromes
= (void *) __get_free_pages(GFP_KERNEL
, 1);
230 pr_err("raid6: Yikes! No memory available.\n");
234 dptrs
[disks
-2] = syndromes
;
235 dptrs
[disks
-1] = syndromes
+ PAGE_SIZE
;
237 /* select raid gen_syndrome function */
238 gen_best
= raid6_choose_gen(&dptrs
, disks
);
240 /* select raid recover functions */
241 rec_best
= raid6_choose_recov();
243 free_pages((unsigned long)syndromes
, 1);
245 return gen_best
&& rec_best
? 0 : -EINVAL
;
248 static void raid6_exit(void)
253 subsys_initcall(raid6_select_algo
);
254 module_exit(raid6_exit
);
255 MODULE_LICENSE("GPL");
256 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
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