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/gfp.h>
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
);
32 struct raid6_calls raid6_call
;
33 EXPORT_SYMBOL_GPL(raid6_call
);
35 const struct raid6_calls
* const raid6_algos
[] = {
44 #if defined(__i386__) && !defined(__arch_um__)
52 #if defined(__x86_64__) && !defined(__arch_um__)
67 #define RAID6_TIME_JIFFIES_LG2 4
69 /* Need more time to be stable in userspace */
70 #define RAID6_TIME_JIFFIES_LG2 9
71 #define time_before(x, y) ((x) < (y))
74 /* Try to pick the best algorithm */
75 /* This code uses the gfmul table as convenient data set to abuse */
77 int __init
raid6_select_algo(void)
79 const struct raid6_calls
* const * algo
;
80 const struct raid6_calls
* best
;
82 void *dptrs
[(65536/PAGE_SIZE
)+2];
84 unsigned long perf
, bestperf
;
88 disks
= (65536/PAGE_SIZE
)+2;
89 for ( i
= 0 ; i
< disks
-2 ; i
++ ) {
90 dptrs
[i
] = ((char *)raid6_gfmul
) + PAGE_SIZE
*i
;
93 /* Normal code - use a 2-page allocation to avoid D$ conflict */
94 syndromes
= (void *) __get_free_pages(GFP_KERNEL
, 1);
97 printk("raid6: Yikes! No memory available.\n");
101 dptrs
[disks
-2] = syndromes
;
102 dptrs
[disks
-1] = syndromes
+ PAGE_SIZE
;
104 bestperf
= 0; bestprefer
= 0; best
= NULL
;
106 for ( algo
= raid6_algos
; *algo
; algo
++ ) {
107 if ( !(*algo
)->valid
|| (*algo
)->valid() ) {
112 while ( (j1
= jiffies
) == j0
)
114 while (time_before(jiffies
,
115 j1
+ (1<<RAID6_TIME_JIFFIES_LG2
))) {
116 (*algo
)->gen_syndrome(disks
, PAGE_SIZE
, dptrs
);
121 if ( (*algo
)->prefer
> bestprefer
||
122 ((*algo
)->prefer
== bestprefer
&&
125 bestprefer
= best
->prefer
;
128 printk("raid6: %-8s %5ld MB/s\n", (*algo
)->name
,
129 (perf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
134 printk("raid6: using algorithm %s (%ld MB/s)\n",
136 (bestperf
*HZ
) >> (20-16+RAID6_TIME_JIFFIES_LG2
));
139 printk("raid6: Yikes! No algorithm found!\n");
141 free_pages((unsigned long)syndromes
, 1);
143 return best
? 0 : -EINVAL
;
146 static void raid6_exit(void)
151 subsys_initcall(raid6_select_algo
);
152 module_exit(raid6_exit
);
153 MODULE_LICENSE("GPL");
154 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
This page took 0.034029 seconds and 6 git commands to generate.