lib/raid6/algos.c

   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,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * raid6/algos.c
  15  *
  16  * Algorithm list and algorithm selection for RAID-6
  17  */
  18
  19 #include <linux/raid/pq.h>
  20 #ifndef __KERNEL__
  21 #include <sys/mman.h>
  22 #include <stdio.h>
  23 #else
  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);
  30 #endif
  31 #endif
  32
  33 struct raid6_calls raid6_call;
  34 EXPORT_SYMBOL_GPL(raid6_call);
  35
  36 const struct raid6_calls * const raid6_algos[] = {
  37 #if defined(__ia64__)
  38         &raid6_intx16,
  39         &raid6_intx32,
  40 #endif
  41 #if defined(__i386__) && !defined(__arch_um__)
  42         &raid6_mmxx1,
  43         &raid6_mmxx2,
  44         &raid6_sse1x1,
  45         &raid6_sse1x2,
  46         &raid6_sse2x1,
  47         &raid6_sse2x2,
  48 #endif
  49 #if defined(__x86_64__) && !defined(__arch_um__)
  50         &raid6_sse2x1,
  51         &raid6_sse2x2,
  52         &raid6_sse2x4,
  53 #endif
  54 #ifdef CONFIG_ALTIVEC
  55         &raid6_altivec1,
  56         &raid6_altivec2,
  57         &raid6_altivec4,
  58         &raid6_altivec8,
  59 #endif
  60         &raid6_intx1,
  61         &raid6_intx2,
  62         &raid6_intx4,
  63         &raid6_intx8,
  64         NULL
  65 };
  66
  67 void (*raid6_2data_recov)(int, size_t, int, int, void **);
  68 EXPORT_SYMBOL_GPL(raid6_2data_recov);
  69
  70 void (*raid6_datap_recov)(int, size_t, int, void **);
  71 EXPORT_SYMBOL_GPL(raid6_datap_recov);
  72
  73 const struct raid6_recov_calls *const raid6_recov_algos[] = {
  74 #if (defined(__i386__) || defined(__x86_64__)) && !defined(__arch_um__)
  75         &raid6_recov_ssse3,
  76 #endif
  77         &raid6_recov_intx1,
  78         NULL
  79 };
  80
  81 #ifdef __KERNEL__
  82 #define RAID6_TIME_JIFFIES_LG2  4
  83 #else
  84 /* Need more time to be stable in userspace */
  85 #define RAID6_TIME_JIFFIES_LG2  9
  86 #define time_before(x, y) ((x) < (y))
  87 #endif
  88
  89 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
  90 {
  91         const struct raid6_recov_calls *const *algo;
  92         const struct raid6_recov_calls *best;
  93
  94         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
  95                 if (!best || (*algo)->priority > best->priority)
  96                         if (!(*algo)->valid || (*algo)->valid())
  97                                 best = *algo;
  98
  99         if (best) {
 100                 raid6_2data_recov = best->data2;
 101                 raid6_datap_recov = best->datap;
 102
 103                 printk("raid6: using %s recovery algorithm\n", best->name);
 104         } else
 105                 printk("raid6: Yikes! No recovery algorithm found!\n");
 106
 107         return best;
 108 }
 109
 110 static inline const struct raid6_calls *raid6_choose_gen(
 111         void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
 112 {
 113         unsigned long perf, bestperf, j0, j1;
 114         const struct raid6_calls *const *algo;
 115         const struct raid6_calls *best;
 116
 117         for (bestperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 118                 if (!best || (*algo)->prefer >= best->prefer) {
 119                         if ((*algo)->valid && !(*algo)->valid())
 120                                 continue;
 121
 122                         perf = 0;
 123
 124                         preempt_disable();
 125                         j0 = jiffies;
 126                         while ((j1 = jiffies) == j0)
 127                                 cpu_relax();
 128                         while (time_before(jiffies,
 129                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 130                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 131                                 perf++;
 132                         }
 133                         preempt_enable();
 134
 135                         if (perf > bestperf) {
 136                                 bestperf = perf;
 137                                 best = *algo;
 138                         }
 139                         printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
 140                                (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 141                 }
 142         }
 143
 144         if (best) {
 145                 printk("raid6: using algorithm %s (%ld MB/s)\n",
 146                        best->name,
 147                        (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 148                 raid6_call = *best;
 149         } else
 150                 printk("raid6: Yikes!  No algorithm found!\n");
 151
 152         return best;
 153 }
 154
 155
 156 /* Try to pick the best algorithm */
 157 /* This code uses the gfmul table as convenient data set to abuse */
 158
 159 int __init raid6_select_algo(void)
 160 {
 161         const int disks = (65536/PAGE_SIZE)+2;
 162
 163         const struct raid6_calls *gen_best;
 164         const struct raid6_recov_calls *rec_best;
 165         char *syndromes;
 166         void *dptrs[(65536/PAGE_SIZE)+2];
 167         int i;
 168
 169         for (i = 0; i < disks-2; i++)
 170                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 171
 172         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 173         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 174
 175         if (!syndromes) {
 176                 printk("raid6: Yikes!  No memory available.\n");
 177                 return -ENOMEM;
 178         }
 179
 180         dptrs[disks-2] = syndromes;
 181         dptrs[disks-1] = syndromes + PAGE_SIZE;
 182
 183         /* select raid gen_syndrome function */
 184         gen_best = raid6_choose_gen(&dptrs, disks);
 185
 186         /* select raid recover functions */
 187         rec_best = raid6_choose_recov();
 188
 189         free_pages((unsigned long)syndromes, 1);
 190
 191         return gen_best && rec_best ? 0 : -EINVAL;
 192 }
 193
 194 static void raid6_exit(void)
 195 {
 196         do { } while (0);
 197 }
 198
 199 subsys_initcall(raid6_select_algo);
 200 module_exit(raid6_exit);
 201 MODULE_LICENSE("GPL");
 202 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");