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__)
52 #ifdef CONFIG_AS_AVX512
57 #if defined(__x86_64__) && !defined(__arch_um__)
66 #ifdef CONFIG_AS_AVX512
78 #if defined(CONFIG_TILEGX)
81 #if defined(CONFIG_S390)
88 #ifdef CONFIG_KERNEL_MODE_NEON
97 void (*raid6_2data_recov
)(int, size_t, int, int, void **);
98 EXPORT_SYMBOL_GPL(raid6_2data_recov
);
100 void (*raid6_datap_recov
)(int, size_t, int, void **);
101 EXPORT_SYMBOL_GPL(raid6_datap_recov
);
103 const struct raid6_recov_calls
*const raid6_recov_algos
[] = {
104 #ifdef CONFIG_AS_AVX512
107 #ifdef CONFIG_AS_AVX2
110 #ifdef CONFIG_AS_SSSE3
121 #define RAID6_TIME_JIFFIES_LG2 4
123 /* Need more time to be stable in userspace */
124 #define RAID6_TIME_JIFFIES_LG2 9
125 #define time_before(x, y) ((x) < (y))
128 static inline const struct raid6_recov_calls
*raid6_choose_recov(void)
130 const struct raid6_recov_calls
*const *algo
;
131 const struct raid6_recov_calls
*best
;
133 for (best
= NULL
, algo
= raid6_recov_algos
; *algo
; algo
++)
134 if (!best
|| (*algo
)->priority
> best
->priority
)
135 if (!(*algo
)->valid
|| (*algo
)->valid())
139 raid6_2data_recov
= best
->data2
;
140 raid6_datap_recov
= best
->datap
;
142 pr_info("raid6: using %s recovery algorithm\n", best
->name
);
144 pr_err("raid6: Yikes! No recovery algorithm found!\n");
149 static inline const struct raid6_calls
*raid6_choose_gen(
150 void *(*const dptrs
)[(65536/PAGE_SIZE
)+2], const int disks
)
152 unsigned long perf
, bestgenperf
, bestxorperf
, j0
, j1
;
153 int start
= (disks
>>1)-1, stop
= disks
-3; /* work on the second half of the disks */
154 const struct raid6_calls
*const *algo
;
155 const struct raid6_calls
*best
;
157 for (bestgenperf
= 0, bestxorperf
= 0, best
= NULL
, algo
= raid6_algos
; *algo
; algo
++) {
158 if (!best
|| (*algo
)->prefer
>= best
->prefer
) {
159 if ((*algo
)->valid
&& !(*algo
)->valid())
166 while ((j1
= jiffies
) == j0
)
168 while (time_before(jiffies
,
169 j1
+ (1<<RAID6_TIME_JIFFIES_LG2
))) {
170 (*algo
)->gen_syndrome(disks
, PAGE_SIZE
, *dptrs
);
175 if (perf
> bestgenperf
) {
179 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo
)->name
,
180 (perf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
182 if (!(*algo
)->xor_syndrome
)
189 while ((j1
= jiffies
) == j0
)
191 while (time_before(jiffies
,
192 j1
+ (1<<RAID6_TIME_JIFFIES_LG2
))) {
193 (*algo
)->xor_syndrome(disks
, start
, stop
,
202 pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo
)->name
,
203 (perf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
+1));
208 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
210 (bestgenperf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
211 if (best
->xor_syndrome
)
212 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
213 (bestxorperf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
+1));
216 pr_err("raid6: Yikes! No algorithm found!\n");
222 /* Try to pick the best algorithm */
223 /* This code uses the gfmul table as convenient data set to abuse */
225 int __init
raid6_select_algo(void)
227 const int disks
= (65536/PAGE_SIZE
)+2;
229 const struct raid6_calls
*gen_best
;
230 const struct raid6_recov_calls
*rec_best
;
232 void *dptrs
[(65536/PAGE_SIZE
)+2];
235 for (i
= 0; i
< disks
-2; i
++)
236 dptrs
[i
] = ((char *)raid6_gfmul
) + PAGE_SIZE
*i
;
238 /* Normal code - use a 2-page allocation to avoid D$ conflict */
239 syndromes
= (void *) __get_free_pages(GFP_KERNEL
, 1);
242 pr_err("raid6: Yikes! No memory available.\n");
246 dptrs
[disks
-2] = syndromes
;
247 dptrs
[disks
-1] = syndromes
+ PAGE_SIZE
;
249 /* select raid gen_syndrome function */
250 gen_best
= raid6_choose_gen(&dptrs
, disks
);
252 /* select raid recover functions */
253 rec_best
= raid6_choose_recov();
255 free_pages((unsigned long)syndromes
, 1);
257 return gen_best
&& rec_best
? 0 : -EINVAL
;
260 static void raid6_exit(void)
265 subsys_initcall(raid6_select_algo
);
266 module_exit(raid6_exit
);
267 MODULE_LICENSE("GPL");
268 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");